March at the JC Raulston Arboretum

This post is 3 of 12 of a series I’m doing this year reflecting back on some of my favorite plants from visiting the JC Raulston Arboretum while attending graduate school at NC State in Raleigh NC. Check back next month for more.

March was always a moody month in Raleigh. Well, I guess isn’t it everywhere? Some years it was filled with gorgeous days, and others it taunted the gardener with late freezes. Nevertheless, there always seemed to be plants in bloom some time during the month at the JC Raulston Arboretum. This month, I look back at some of my favorite trees, shrubs, and perennials that welcomed spring. I hope these images inspire you to try some new plants in your garden. I know learning about them helped to build my palette of plants to use for the beginning of the gardening season.

THE TREES

There was an incredible Magnolia collection at the arboretum. Here the vigorously growing Magnolia × loebneri 'Merrill' flowers in the White Garden. This selection is quite hardy up into the northern states.

One of my favorite magnolias is Magnolia × kewensis 'Wada's Memory'. I love its cut-handkerchief-like petals, and I’m considering using this cultivar around our house.

Each spring I loved seeing the floriferous Magnolia stellata 'Chrysanthemumiflora' in bloom. The pink blossoms are so voluminous, and this tree’s short stature welcomes its use in smaller gardens.

Near the Ruby McSwain center was the Asian Sassafras tzumu with its tiered branching habit classic to Sassafras species.

As the flowers fade, the new foliage emerges on Sassafras tzumu with a similar textured Yucca in the background.

J.C. raved about Halesia diptera var. magniflora and for good reason. This variety from Florida highlands features beautiful white flowers a little bigger than a thimble that cover the tree in early spring. This species does well in Texas, too.

A close up of Halesia diptera var. magniflora

I can’t wait to try Melliodendron xylocarpum in Texas. I adored this tree’s Easter egg shaped buds that would open to…

…beautiful star-shaped white flowers. I recall that some years Melliodendron xylocarpum would get burned by late freezes, but like many early spring flowering plants, planting them is certainly worth the risk.

THE SHRUBS

Exochorda racemosa is shrub that takes our heat and humidity in the south well. The little buds look like pearls, hence the name pearlbush. I always enjoyed looking at the intricacies of the flowers once they open.

Spiraea thunbergii 'Ogon' is a reliable flowering shrub that is covered with white flowers in early spring and followed by thin, golden leaves.

A subtle color echo between the emerging foliage on Spiraea thunbergii 'Ogon' and its orange pistils.

Last month I shared my love of Stachyurus. Even more plants would be flowering in March. Here Stachyurus praecox 'Issai' flowers with a Chaenomeles in the background.

There was even a Stachyurus selection—Stachyurus praecox 'Rubriflora'—that had buds and petals blushed pink.

A really interesting and uncommon shrub I learned about at the arboretum was Parrotiopsis jacquemontiana. This member of the witch hazel family would be covered in flowers in March.

In this close up of the flowers on Parrotiopsis jacquemontiana, you can see the plethora of stamens and the skirt of white bracts underneath.

Edgeworthia chrysantha was in full bloom in March many years at the arboretum. The flowers face down, likely to protect the pollen from rain.

Neviusia alabamensis is a novelty native shrub that slowly spreads via rhizomes in the garden. It is rare throughout its range, but deserves wider use for its dainty flowers.

I enjoyed the pompom flowers of Neviusia alabamensis so much that I now have this growing in my Texas garden.

The late witch hazels would still be flowering in March. Here Hamamelis mollis 'Wisley Supreme' flowers with a carpet of Narcissus underneath.

While most lilacs don’t do well in the south, Syringa × laciniata was always a beautiful bloomer in the arboretum and tolerated heat well.

The lavender flowers of Syringa × laciniata

THE PERENNIALS

I also learned about Tulipa clusiana selections at the arboretum. This species tends to do better in the south and can grow well in gravel gardens. Here ‘Cynthia’ flowers with creamy yellow and salmon petals.

Another clusiana type was ‘Peppermint Stick’, named for its red and white petals.

Don't Neglect This Muscari

Muscari neglectum is in full flower here at our homestead.  In my search for naturalizing early spring geophytes for east Texas, I heard this species would grow well for us.  I had seen yards full of it in the hill country further west in the state.  I’ve killed other grape hyacinths like Muscari armeniacum.  They’ll last for a season or two, but eventually fade.

However, this species, well, the epithet gives you an idea of the conditions this starch grape hyacinth tolerates. My plants came from an abandoned lot in town next to a makeshift parking lot. Nearby a discarded sofa and a chair sat, and being early spring, the grass and weeds hadn't grown up enough to hide the little purple bottles I spied passing by.

Late one afternoon, I decided to go dig some of the bulbs, and on a whim, I asked some students if they wanted to go help me rescue some of these geophytes.  I figured that with the numbers I saw we could even use some in our plantings on campus.

When we arrived, we discovered dense clumps of this heirloom flower. Some bulbs had found purchase under the turf but others were exposed and sitting on top of gravel and in full flower! They were surviving, dare I say even thriving in this ruderal soil. I assumed this location was where an old driveway of a house used to be. We dug a few clumps, and then made our way back to campus to parse out our new accessions.

A handful of an original clump from the abandoned lot. These Muscari are quite easy to divide; lift them and then rip apart into smaller groups.  It always amazes me how many bulbs are in one clump.

Once home, I planted them into a bed where I was already developing a cool-colored theme for spring. Planted nearby were the fuschia Glandularia canadensis and the soft blue Ipheion uniflorum. 

Muscari neglectum flowers against the backdrop of Glandularia canadensis. The burn you see on the Muscari and Gladiolus foliage is from the February freeze.

That was two years ago. Now, for much of March, these three play off each others colors and are some of the first plants to start flowering in my beds. I love watching bees of all kinds flit about the flowers.  One must get close to appreciate the finer details of the blooms, the little jugs with their white pencil-thin rims.  And, the color gradient of the raceme’s flowers is so rich as it changes from indigo below to a periwinkle top.  Once pollinated, the flowers become small tetrahedral seed capsules.

I have also planted them in our fledgling orchard on its shadier side where fewer Claytonia virginica grow.  They look like little purple rock candy suckers sticking out of the rough turf.  The darker slivers of the Muscari feel right in the dappled light, and unlike the fair-weather Claytonia virginica that only opens when the sun shines, these flowers are always on show. 

In the time since I planted my first bulbs I have watched each year as my plants multiply, both naturally and by division. I find myself pulling apart thick clumps anytime they aren’t in flower, which is easy since their bad-hair-day foliage has been up in the garden since early October. The wetter soils of winter welcome the splitting.

The leaves curl a bit, like a bad hair day

The little slivers of Muscari emerging in a bed amongst other perennials

But, I discovered something new about propagating this species last year.  Weeding one day I found a clump whose roots had been nibbled on by blasted gophers, and in pulling out what was left to reset in firm earth, I noticed that some of the bulbless leaves had roots on them!  I was amazed.  Eucomis is the only other geophyte that I know where more plants can be made via leaf cuttings, so this discovery was quite delightful.  They are both in the Asparagus family, so perhaps there is some family connection with this adaptation. I am happy to know yet another approach to making more of this great geophyte.

Adventitious roots on the bottom of Muscari leaves. Look closely and you’ll even see new bulbils.

Gibbs Gardens

“Jared, we have to go see this garden in Georgia.” On the phone was Mom, and she was telling me about where she read in an early 2012 Southern Living that Gibbs Gardens was about to open its doors to the public for the first time ever. I had never heard of the garden, but she shared about how the article said 5 million daffodils had been planted. I was on board.

So, we planned to meet up the first weekend in March that year for the opening weekend. That Friday night was a bit crazy as vehement storms passed through with rain and hail. At one point, it was so rough we were even discussing going to the hallway or stairs in the hotel. But, the storms passed, and we woke the next morning to find the sun shining.

I told my parents we had to get to Gibbs Gardens early because since this weekend was the first time the garden was open, I knew it would be packed. I had travelled to many gardens before and sometimes been turned away when parking lots were full. So, I knew being just an hour north of Atlanta, there would be crowds. But, when we arrived, we were one of three cars in the parking lot. Haha! We had the whole place to ourselves! I should note in later years when I’ve gone, the parking lot is now packed and people are running to get the good photograph spots without any people in them. So, we certainly lucked out this weekend.

Walking through the garden, the reputation of a world-class garden certainly lived up. There were daffodils everywhere. Millions of them. The website states that over the years with division the garden likely has over 20 million Narcissus on site, which is just a mind boggling number of blooms. I’ll let the photos tell more of the story below.

I would never wish low attendance numbers on a garden, but it sure was nice to be some of the first people there that morning enjoying the garden by ourselves.

One design feature used at Gibbs Gardens was curvilinear lines. They swayed and curled through the landscape, often following the topography of the hills.

I always love to see Narcissus planted on hills because passers-by can better see into their faces.

Just like the Greek myth, these Narcissus admire their own beauty in the pond reflection.

The plantings at Gibbs Gardens were grandiose where ribbons of cultivars were planted on the hillsides and there were flowers as far as the eye could see. Notice the hillside in the distance and check out the next photo.

Here is that hillside upon closer inspection. We were so happy to see that the storms didn’t pound the flowers down too bad.

While cultivars weren’t labelled, occasionally I would see one I knew like these ‘Ice Follies’.

Narcissus plantings also provide a nice backdrop for family portraits of Mom and Dad. :-)

It was nice to see how other plants were integrated in with the Narcissus plantings. Here Edgeworthia, Chamaecyparis, and a hiding coral bark Acer palmatum ‘Sango Kaku’ are surrounded by daffodils.

I adore Edgeworthia chrysantha for its winter perfume and clusters of fuzzy yellow flowers. As a member of the Thymelaeaceae, they have this cool feature where some branches will have three shoots instead of the typical one or two of most species.

Narcissus can be planted beneath deciduous trees to provide color in early spring and brighten these dappled spots before the trees leaf out.

I enjoyed the subtle color echo here between the orange cups of the Narcissus and the golden marcescent foliage of the Fagus grandifolia.

Gibbs Gardens also featured a tranquil Japanese-styled garden.

A broader shot of the Japanese garden reveals plants integrated with rocks, water, and statuary.

This planting is so simple yet effective—the bold foliage of three Rohdea japonica in a fibrous mat of Ophiopogon japonicus ‘Nana’.

Acorus gramineus ‘Ogon’ snakes through this planting and echos the golden Chamaecyparis along the pond edge.

At the top of the property is the Manor House Gardens, which are planted with winter color like Viola.

An arbor near the house was planted with Viola, Acorus, and Euphorbia to provide late-winter interest.

Gibbs Gardens was the first time I had ever seen parsley used as a groundcover underneath tulips. I thought it a clever idea to hide their sometimes lanky bases.

I saw another one of my favorite winter flowering shrubs at Gibbs Gardens, Corylopsis pauciflora. The numerous small flowers on this dense shrub form a buttery haze.

A close up of the pink buds and emerging yellow flowers of Corylopsis pauciflora, or buttercup winter hazel.

Even in their fall, Camellia flowers are beautiful. This one planted near the Manor House I suspect to be ‘La Peppermint’.

Walking down from the house to leave we saw more mass plantings of Acorus. I liked the subtle color echo here between Edgeworthia and Acorus gramineus ‘Minimus Aureus’.

Again, more use of curvilinear lines in the landscape with Acorus gramineus ‘Ogon’.

And, I even admired here where the moss and Acorus shared a similar hue.

One last shot of the incredible plantings of Narcissus at Gibbs Gardens. It was a great weekend with my parents, and I’ll never forget of seeing millions of daffodils in flower.

Celebrating Emergence

The shift to spring is now palpable here at our east Texas homestead. I notice the sun's early morning rays shining more in our backyard, the temperature is hovering the in 60's or 70's most days, and spots of green are popping up in the landscape.

Emergence in the plant world is filled with such anticipation. Around us life is erupting, and it is so good to see fresh growth in a landscape scarred and burned from the extreme cold a fortnight ago.

The daffodils are up. Well, most of them are. I thought this would be a daffodil-less spring as many of the early tazetta types from the Mediterranean were bleached white. But, those that have more northern European blood seem to have made it through safely. The yellow-orange 'Ceylon' and large-cupped yellow 'Carlton' are now beginning to bloom. I noticed their buds above the snowline, but they still survived the cold. These are two Narcissus cultivars that actually do well for us here in east Texas and will increase in number with the years. Most modern hybrids just don't get adequate chilling to flower or grow well.

A bit of burn on the tips of the foliage of these ‘Ceylon’, but other than that, the cold didn’t phase them.

Narcissus pseudonarcissus are now flowering, too. They are much smaller than the varieties above, but I love their diminutive size. I recall seeing their minute buds huddled among the blue-green foliage as I scurried about preparing for the coming cold and wondering if they would survive. Seeing their buttery yellow coronas reminds me of my youth and the abandoned yards full of them on the backroads in Tennessee marking where homes once stood. Even then I would pick handfuls of them to bring their sweet scent into our house, much like I did ahead of the two inches of rain we got this past weekend.

This line of Narcissus pseudonarcissus flowers faces south, soaking in the sun.

Ahead of the rain I divided some large clumps of Narcissus pseudonarcissus and planted them into the beds near our house that I have been developing into naturalistic plantings since our arrival here a little over three years ago. These plantings needed more early spring color, and I plugged in the bulbs before the rain started amongst the emerging foliage of Pycnanthemum and a nice purple foliage form of Tradescantia gigantea I found.

I randomly scattered Narcissus pseudonarcissus into this bed over the weekend. Though I’m not done yet, my goal is to have small groupings, denser in the middle and then less bulbs on the outside.

Ahead of the rain was also a good time to move 20+ Penstemon tenuis and 30+ Penstemon digitalis plants I grew in propagation beds from last year. Both were derived from seed that I collected from plants growing here, and they were just barely beginning to produce shoots out of their basal rosettes. Now I feel like I have enough plants to make an impact come April for the purple-flowering Penstemon tenuis and May for the white-flowering Penstemon digitalis. I was surprised at how shallow their root systems were. I was able to scoop them up with a shovel almost like one would scoop lasagna out of a dish and place into a similar shaped hole.

A wheelbarrow of Penstemon digitalis ready for planting. You can see the fresh foliage beginning to pop.

Nearby other natives are emerging, and it is a real cast of characters—Arnoglossum plantagineum, Trillium ludovicianum, Antennaria parlinii, Sanguinaria canadensis, Stenanthium gramineum, and even my Sarracenia in the bog. All of them know it’s time to grow.

I delight in seeing the hosta-like foliage of Arnoglossum plantagineum. Plants have finally gotten to a decent size at our place, and soon their shoots will rise for form a white corymb of rice-shaped flowers.

I was also happy to see my Trillium ludovicianum emerging amongst the groundcover of Antennaria parlinii I planted to mark the ephemeral. You can barely see the chicken wire cage that I planted it in to protect it from the gophers that plague our property, and if you look closely, you’ll see some one-leaved baby Trillium in the center!

The fists of Sanguinaria canadensis are shoving their way out of the soil and begun to unfurl as leaves.

The slivers of foliage on Stenanthium gramineum emerge from the ground. I’ve always found their maroon sheaths near the ground to be attractive but quickly hidden by the foliage.

I squealed this weekend when I discovered the antennae-like flower buds emerging on this Sarracenia flava ‘Black Ascot’ when cutting back the pitchers.

Yes, all this fresh growth of spring is truly wonderful . Sure, we may have another frost or two along the way, but for now I will celebrate emergence and the return of my many photosynthetic friends to the garden after their long slumber. It is so good to see them again.

February at the JC Raulston Arboretum

This post is 2 of 12 of a series I’m doing this year reflecting back on some of my favorite plants from visiting the JC Raulston Arboretum while attending graduate school at NC State in Raleigh NC. Check back next month for more.

February was one of my favorite times to visit the JC Raulston Arboretum. With the hold of winter receding, walking around the garden was a scavenger hunt in discovering what flowers were in bloom. Even the smallest of flowers were appreciated as the gardening season began to awaken. After visiting for a few years, I became more aware of the flowering schedules and knew better what to expect. Sometimes plants would bloom early, sometimes they would flower late, but February seemed to always be a reliable time to start seeing color increasing in the garden.

For this month’s reflections from the JC Raulston Arboretum, I wanted to share some of my favorites for late winter color. Reviewing these photographs reminds me of how many of these plants I actually need to try in Texas!

I enjoyed studying the Prunus mume collection in the garden. Even going back to J.C.’s first newsletter, he spoke highly of them. This cultivar is ‘Bridal Veil’, a really nice weeping form.

A close up of ‘Bridal Veil’ flowers

Close to the stairs of the Ruby McSwain Visitor Center was ‘Omoi-no-mama’, a nice white-to-blush, semi-double flowering form of Prunus mume. I really liked the placement and how walking up the stairs allowed me to get my face in the flowers.

The arboretum had a few specimens of the winter flowering Cornus officinalis and Cornus mas. In the winter garden was ‘Kintoki’, one of my favorite forms of Cornus officinalis selected by Barry Yinger for its beautiful exfoliating bark.

Near ‘Kintoki’ in the winter garden was Chaenomeles speciosa ‘Contorta’. It was a scraggly thing with its contorted flowers, but getting up close with the blooms I made an amazing discovery.

Even the stamens were contorted! How cool! Whatever genes were making the branches bend also curled the flower stamens. I noticed that the sun was about to shine on the blossoms, so I hung around and got a good progress photograph of sunlight hitting the flower. I use these images in my classes to illustrate how light can change the appearance of flowers.

Here is a minute later when the sun barely began to shine on the flowers producing a nice glow. This diffused light shot is my favorite of the three.

And, here another minute later the light is a bit harsher.

Another genera that I fell in love with at the JC Raulston Arboretum was Stachyurus. Here we see ‘Sterling Silver’ wearing its strings of pearls. I can’t believe I haven’t tried these yet in Texas!

Perennials would also start popping around this time of year. I always enjoyed seeing this large planting of the aptly named Narcissus ‘February Gold.’

Most people are familiar with the yellow form of Narcissus pseudonarcissus, but I always thought that these cream Narcissus pseudonarcissus subsp. moschatus looked charming in the perennial border.

I would lay on the ground to photograph Ipheion that barely rose six inches of out the soil. It is like someone stenciled black lines on the undersides of the petals of this ‘Wisley Blue’.

Now I appreciate Ipheion even more as they are one of the few early geophytes that we have flowering in east Texas this time of year. Some like ‘Froyle Mill’ have a really nice purple color.

Iris unguicularis was another reliable winter flowering perennial. It is unfortunate that the flowers are so hidden.

So, you have to get into the clump of Iris unguicularis to really appreciate the flower intricacies.

Another iris in bloom was Iris tuberosa (or Hermodactylus tuberosus), a really novel perennial. Finding a plant with green and black flowers in February is so funky.

Here’s a close up of the flowers on Iris tuberosa. The black falls seem like velvet.

I also enjoyed seeing the spiraling Euphorbia rigida on the roof garden of the Ruby McSwain Visitor Center. The leaves and flowers had such psychedelic colors for late winter.

Walking around one afternoon, I noticed that this plant had flowers in the middle of the leaves! Turns out these “leaves” are actually flattened stems or cladodes on Ruscus × microglossus.

A close up of the quirky Ruscus × microglossus. Students really find these plants fascinating because of the position of the flowers.

A Cold Week in Texas

At 7:24 AM on February 16, our thermometer here in east Texas read -6F. Back home in Tennessee, I’ve walked out in 0F when the moonlight made our snow covered fields glow as if it were day, I’ve flown into Boston to present in between two snowstorms that year the snow didn’t melt until July, and I even spoke the day after the frigid polar vortex descended on Chicago. But, this is the coldest temperature I’ve ever experienced in my life. It is also funny to note that this is the most southern place I’ve ever lived. We’ve had a winter trifecta hit us this week— 6 inches of snow Monday morning, followed by extreme record breaking cold Tuesday morning, and then an ice storm on Wednesday. At one point the whole state of Texas—all 254 counties—was under a winter storm warning.

We have been mostly fine through this insane weather event so far, and I appreciate the messages from readers and friends checking in on us. We had power on and off until Wednesday at noon went it went off and water until Thursday night due to the water company. My heart breaks, though, for those who have been through worse times this week (you can learn more about helping here and here).

But, who would have ever thought we would hit -6F? The airport registered -3F, so I believe my reading in our little valley homestead. The coldest I’ve measured here at the house before this week is 11F. It even drove Dark-eyed Juncos south to our feeder, my first observation of them here at our house.

These temperatures have made me think about plant hardiness. Hardiness is of course a measure of a plant’s survival based on the average annual extreme minimum temperature. Nacogdoches is located in USDA Hardiness Zone 8b, where on average our minimum winter temperature is 15 to 20F. Just after midnight on the 16th, we were at 0F, which means that for 7-to-8 hours we were basically USDA Hardiness Zone 6 (-10F to 0F), which occurs in the panhandle of Texas, the Kentucky/Ohio border, and on the coast of Maine.

It will be interesting to see what plants survive from this event. As horticulturists we are both horrified and intrigued by the question, “What survived?” These extreme weather events interacting with our plants are opportunities to learn what died and to celebrate what lived.

But, hardiness is not an absolute. It is just a measure that gives us some idea of how the cold can impact plant growth. Cold can affect a plant’s hardiness at three points during winter—an early freeze before the plant has acclimated to winter (17F in November that zapped my Magnolias and citrus a few years ago), an extreme winter temperature minimum (here’s looking at you -6F), or a late freeze that may kill a plant after it has resumed growth, whether that be after the frost free date (like the 2007 April freeze) OR after an extreme warming even in winter.

As we go forward into the next few weeks and months here in the deep south, we will see plants die, especially broad leaf evergreens and tropicals, and some plants live. In some cases the living and the dead may be right next to each other or a short distance away. So, we have to remember that hardiness is a combination of so many factors. Sitting in front of the fire this week scribbling notes down for my weekly blog post, I reviewed the lecture “Untangling the Hardiness Question: What is Hardy and Why?” by Dr. J.C. Raulston included in Bobby Ward’s biography of this incredible horticulturist, Chlorophyll in His Veins. Raulston went through a whole gamut in this lecture he once gave to the North American Rock Garden Society in Seattle, WA in 1995. I wanted to briefly list the factors he discussed below.

• Cold — Gardeners quickly connect cold weather with seeing plants die. Raulston noted that using minimum averages is a complex attempt to simplify the effects of cold on plants. One of my favorite quotes he said was, “I can go into the kitchen and put one hand on a gas flame and the other in the freezer and on average I am very comfortable, but you have problems when you hit those two extremes.” Even the type of cold that manifests matters. For example, convective cold usually occurs because a cold front moves into a region. However, radiative cooling is where heat is lost to the atmosphere on cool nights. The example for radiative cooling that Raulston gave is it may be 38F on the thermometer, but the leaf is 28F. We see this in fall on tomatoes on cool mornings.

• Provenance — Where plants or clones of a particular species originated could have resulted in accumulation of traits that increase (or decrease) survival, just because they are growing in Texas instead of Michigan. They are still the same species, but they have adapted in those areas to the conditions they endure. That is often why growers like to get genetics from nearby or a particular part of the country to grow. But, some species may be hardier than the zone in which they grow. Raulston mentions Magnolia ashei as a great example. This native is found in the panhandle of Florida, but the species is hardy in Chicago. Likely, it is a relic from the last ice age that was pushed south and not able to advance back north.

• Population variation — Even within a population of plants from a single cross between two parents, there may be a wide array of different cold tolerances in individuals.

• Cellular location of freezing — Does freezing occur in the cell? Then, that cell ruptures and death is likely. Does freezing occur in the cell wall? Then, the cell is probably fine, and the tissue will likely live.

• Microclimates — Buildings, stones, pavement, windbreaks, and water may all moderate local temperatures and create microclimates, whether they be warmer or cooler. Until this freeze, we still had ‘Pele’s Smoke’ sugarcane overwintering near our campus greenhouse and starting to put up new growth, and yet it is only hardy in zone 9 and south.

• Snow protection — Snow may protect the bottom of plants, but kill the top. Honestly, I’m hoping for this effect on a number of my plants at home. I noticed our rosemary this morning starting to turn black, but near the base were some hints of green.

• Root hardiness — Can the roots survive the cold spell, even if the top of a plant dies? We really see this difference with plants that are in pots versus in the ground. I moved my container woodies that I haven’t gotten into the ground yet into the garage to protect them. And, I’m hoping that some of my tender perennials make it through because their tops were not exposed (and, their roots were covered with 6 inches of snow!).

• Chilling requirement met — Many woodies have to experience chilling hours to be able to flower, and websites log the hours for different regions. If they have met their requirement, then the cold may damage buds. And, if not, then the plants should be ok. I’m hoping that my peach buds were still tight enough to survive the cold. Time will tell.

• Nutrition — Many experts recommend to stop fertilizing perennials and woodies in late summer and early fall to help them survive. Raulston talked about in this lecture about an experiment where azaleas that were fed all the way up until frost didn’t survive. The plants kept growing actively and didn’t have a chance to shut down. The experimental control azaleas that didn’t get fertilizer at the end of the growing season overwintered just fine.

• Active growth — Is the plant growing? Many plants acclimate based on photoperiod, temperature, or some combination of both. The lack of appropriate acclimating could result in death. Raulston noted that a plant could survive in Siberia at -75F but in active growth die at 25F.

• Summer heat — Some plants like Cercis canadensis var. texensis need summer heat to be able to overwinter well. He mentions how if you grow this in a hot summer, it’s hardy to zone 6, but if grown in the Pacific Northwest, it may only be hard to Zone 8. For other plants, the summer heat drains their sugar load so that they don’t have enough carbohydrates to overwinter.

• Scorch — Scorch occurs when the plant is cold but the sun is shining, and water loss from the leaf is high. I’ve even heard Eliot Coleman say that he thinks that scorch and wind desiccation of plants hurts some winter edibles more than the cold.

So, yes, plants are going to die or be damaged from this extreme cold event, but keep in mind that many of the above factors could nudge them towards death or pull them towards life.

The other question is where do we go from here? How do we respond in our planting to such an event? In Raulston’s talk, he stated that as horticulturists we accept risks, and sometimes we even dare to grow the impossible for pride and glory. He also stated that what would help us assess hardiness would be to have cold measured on a scale of x-year freezes like we have x-year floods. Raulston talked of a 250-year freeze in his lecture when parts of North Carolina dropped to -10F. That way, we can decide whether we want to use certain plants. And, perhaps this risk can be determined when designing or planting by moving up or down a hardiness zone. That way we have stalwarts that can take anything and less reliable plants that are garnishes in a planting with the understanding that we could loose them in a bad year.

So, maybe -6F is a 250 year freeze? Nearby Tyler, TX set an all time low record of -6F, and records date back 138 years to 1883. But, we also have to ask the question was this event a one off or are more events like this coming due to a changing climate? The science isn’t so clear, but a warming arctic could destabilize the cold air at the North Pole and result in more cold entering the United States. On this matter, too, time will tell.

As someone who loves cold, snow, and winter, I am ready for warmer days. It will be interesting to see now what the next flowering plant will be. Much of the Narcissus and Magnolias are zapped. But, the march to spring continues even with this rough week. The temperature will be 60F on Sunday. Which, if we still don’t have power, will be warmer than our house!

A Grand Narcissus

I have always delighted in seeing the first Narcissus of the year emerging from the ground to herald that spring is near with their bright trumpets.  Of course, it's funny writing that now that I live in Texas because our in-the-ground paperwhites can start blooming at the end of November.  So, I've had to delay my expectations a bit.

One species that holds to flowering at the end of winter is Narcissus tazetta, the Chinese sacred lily. It has become one of my favorites since moving to Texas.  While the species is native to southern Europe, Asia, and northern Africa and has a fascinating history, this geophyte has naturalized in the south, even into parts of southern Arkansas. Scott Ogden notes in his Garden Bulbs for the South that this perennial is a stalwart and has survived many decades on abandoned homesteads, a living testament to someone who once lived there. They also don't need division to keep them floriferous like other daffodils do.

The planting of Narcissus tazetta ‘Grandiflora’ in the Plantery on campus

There is a thick line of them planted on the north end of our Plantery greenhouse at school where their flowers beam and greet students, faculty, and visitors passing by. Most tazetta types have a cluster of smaller flowers at the top instead of one large bloom with petals and corona, the circular projection on a Narcissus. Research a few years ago demonstrated that these trumpet-shaped growths, a unique feature on Narcissus, are not an extension of the petals or stamens but a fifth floral part that develops after the other floral whorls arise in a young buds. It is these cups—no matter how big—that we love to stick our noses in to sniff the sweet smell of spring. But, in this small space between the greenhouse and headhouse, the flowers perfume the whole area with their sweet scent.

In conversations with Greg Grant, I learned that he planted them here about 30 years ago, which illustrates its robustness. I love how they are sited underneath Panicum 'Northwind'.  The grass emerges to hide the thick Narcissus leaves as they fade, and once the brown Pancium is about ready to cut back after winter, the green straps are rising from the bulbs. 

This particular form of Narcissus tazetta is quite vigorous. While I thought it was 'Grand Primo', Greg said that this selection is an unknown cultivar. His stock came from Celia Jones who originally got these plants from her grandmother who ran Sister's Bulb Farm in Gibsland, LA. They were sold under the name “Paperwhite Grandiflora”, a likely hybrid between Narcissus tazetta var. orientalis and Narcissus papyraceus. It is known that many hybrids between these two genera occur. Pulling again from Garden Bulbs of the South, Scott Ogden stated that Narcissus papyraceus is a diploid (two copies of DNA), and Narcissus tazetta is a tetraploid (four copies of DNA). So, the resulting hybrids are often triploid, and having three sets of DNA usually makes a plant sterile. It is possible to have some hybrid vigor with these selections, possibly because of the lack of seed but also because of the perfect combination of genes.

I’ve been trying to sort out these tazetta types because I have two forms at my house I’ve rescued from abandoned sites. One is the shorter ‘Grand Primo’ with darker yellow cups, and the second is very much like this taller form. In fact, they may very well be the same selection.

‘Grand Primo’ at my house. Notice the darker yellow cup and shorter height compared to the ‘Grandiflora’ type above.

I do feel for them this year and all the other plants that tried to welcome spring early.  We have a record breaking cold front descending from high up in Alberta this weekend that could bring snow, ice, and the coldest temperatures this region has seen in decades. It will be interesting to see how they make it through it all. I’m not worried about them surviving, just sad to see potential flowers go. I picked some flowers to take to my office to enjoy out of the cold where the blooms will last for a good week in water. Even if spring is interrupted outside, I’ll try to keep it going indoors.

A frosted ‘Grandiflora’ type at my house.

Witch Hazels at The Scott Arboretum

I’ve been enamored with witch hazels ever since I realized they were a thing. As a young horticulturist, I was amazed to discover that a species could flower in the dreariest of winter weather.  And, bloom they do, their petals blazing yellow, orange, red, and even purple against a cold winter sky. These pompoms of color warm the heart and say spring is near.  Where I’ve lived in Tennessee and North Carolina, these have been planted in the gardens I knew and visited, but now living in Texas, they are largely absent from the landscape, save for a few native species.

So, I was happy a few years ago when Karen and I travelled to Philadelphia for a business trip in February.  I wanted to show her The Scott Arboretum where I had interned 10 years ago at the time.  (Wow, has it really been that long?)  I had visited this beautiful campus in spring, summer, and fall but never winter.  I was hopeful that the Hamamelis would be in full bloom. The collection features all kinds of Hamamelis vernalis, Hamamelis × intermedia, and Hamamelis mollis.

We made our way through campus as a cold rain diminished and left a dismal sky in its wake. Yet near the Cunningham House, the pale yellow ‘Luna’ glowed. It is considered by some to be one of the lightest forms available. 

The honey colored ‘Luna’

Around the back the short and dense ‘Quasimodo’ echoed the color of the stem colors found in the Cornus planted nearby. It is such a good cultivar for small spaces.

‘Quasimodo’ is such a cutie. It is short and sweet.

The colors on the petals of 'Quasimodo' were echoed by the nearby Cornus alba ‘Bud's Yellow’ (front) and Cornus sanguinea ‘Arctic Sun’ (back).

We continued past Parrish Hall in the center of campus and the long allée of swamp white oaks to find a few witch hazels on the other side just above the famous amphitheater.  ‘Strawberries and Cream’ had this delicious red to yellow fade outward on the petals that mellowed the color.  Also nearby was a young ‘Diane’, one of the best red witch hazels. She still clung to her marcescent coat of leaves, but I found a perfect spot to navigate a photo without the clingy foliage. 

‘Strawberries and Cream’ just looks delectable, doesn’t it?

‘Diane’ is considered one of the best red forms.

I can’t talk about Swarthmore and The Scott Arboretum without showing you the beautiful natural amphitheater with the scattered tulip poplars.

I almost missed my favorite specimen of the day.  On our way to the main collection, I passed by the Clothier courtyard, but with a quick glance back my eyes caught a blob of yellow and I stopped in my tracks.  Espaliered against the north wall of the courtyard in the fragrance garden was Hamamelis mollis ‘Early Bright’.  Reading in Chris Lane's book Witch Hazels, I realized that this cultivar was found at The Scott Arboretum as a chance seedling, and the name was registered by my friend Andrew Bunting who was curator there for many years because it bloomed a few weeks earlier than other Hamamelis mollis forms.  Seeing it espaliered gave me some serious plant lust for wanting to grow witch hazels in east Texas.  Alas, we lack the winter cold that fans their buds into flames.

Clothier Hall. The courtyard is to the right of the bell tower.

My jaw dropped when I saw this incredible espaliered Hamamelis mollis ‘Early Bright’.

This espaliered ‘Early Bright’ was quite large.  Karen helps us get a sense of scale.

Our arrival to the collection proper near the tennis courts was quickly evident as hazes of crimsons, tangerines, and saffrons filled the drab landscape with color.

Hooray! The main witch hazel collection is in bloom!

I was so impressed by the sheer size of the plants.  Most of the time I see young developing witch hazels in gardens, and I had never seen Hamamelis this large.  Two behemoth specimens were ‘Jelena’ and another ‘Early Bright’, this time allowed to grow into its true form.

Ah, what an incredible specimen of ‘Jelena’. I would say this cultivar is one of the best and most popular forms in the US. Sadly, my two-year old plant is about to die here in Texas due to the lack of winter chilling.

Staring at ‘Jelena’ is like looking at a fiery sunset.

And, here is a large ‘Early Bright’ in full flower.

A close up of ‘Early Bright’.

I really like collections like this because it allows one to study the plants and see their growth and seasonal differences. Some like ‘Primavera’, ‘Feuerzauber’, and ‘Wisley Supreme’ were in full bloom while others like ‘Gimborn's Perfume’ and ‘Sunburst’ had yet to flower.

‘Wisley Supreme’ is one of my favorite yellow forms.

Another good red is ‘Feuerzauber’. It tends to grow more vigorously than ‘Diane’

I love seeing the curls in Hamamelis petals like you see here on ‘Primavera’.

‘Red Imp’, a fun named selection of Hamamelis vernalis, held onto its leaves.

Having seen most of the flowering specimens in the collection and with light waning, we left. It was so much fun to visit this collection and get a better idea of which witch hazels deserve more use and attention in gardens. I hope this overview provides a few ideas and inspiration about using witch hazels in your garden.

Winter Sowings

Sowing perennial seed is one of my favorite tasks of winter.  There's so much anticipation wrapped up in this simple practice, even more so than sowing say lettuce or tomato seeds with their quick germination.  Perennial seed, both woody and herbaceous, may take weeks or months before the first hint of green is seen, so even in this waiting there is an air of mystery. My eyes hover over the trays as I search for life, and I find myself wondering if and when.

Many perennials have evolved to use the exposure to wet cold as an indicator for when they should emerge from dormancy and resume growth.  When I teach the concept of this physiological dormancy to students, I liken this period to an alarm clock.  Seeds have to get the appropriate amount of wet chilling time for the maximum number of seeds to germinate (or “wake up”).  Without this exposure, none or only a few may start growing (as far as the few goes, variation does exist within a population!).  This moist chilling results in physiological changes to the embryo that then allow the seed to overcome dormancy. You can hypothesize how this could be selected. Those that emerge early die in the cold. Those that bide their time awake to a glorious spring and can pass on their traits.

The staggered germination of Echinacea sanguinea. Note that there are a few larger ones with two or three true leaves that evidently didn’t need any chilling to enhance germination, but many seeds did and have only their pair of cotyledons. Don’t mind the wavy-leaf Streptanthus on the bottom or the couple of Penstemon tenuis that creeped into this block.

While this method of overcoming of dormancy occurs in nature, we horticulturists call the practice where we expose seeds to cold and moist conditions cold stratification (there is also warm stratification for some seeds, hence the addition the modifier).  Usually the seeds are placed in moistened sand, perlite, vermiculite, peat moss, or some blend of those; I've even used paper towels and coffee filters if they go into the fridge.  Now, mind you, all seeds don’t need this exposure.  Again, I recommend Norman Deno's wonderful online Seed Germination Theory and Practice to investigate the requirements. 

I've always wondered about the etymology of the word stratification. Strata means layers, not seed. Then, I read in Hartmann and Kester’s Plant Propagation: Principles and Practice how nurseries used to make layers of seed that were separated by moist substrate in outdoor pits. These “strata” were allowed to overwinter there.  One of the earliest historical writings about stratification is found in Sylva by John Evelyn in 1664.  I've shared his writing below of how he recommended stratifying, and to save myself from writing "[sic]" every other word, just note that spellings back then were a bit different. 

“Chuse your seed of that which is perfectly mature, ponderous and sound; commonly that which is easily shaken from the boughs, or gathered about November, immediately upon its spontaneous fall, or taken from the tops and summities of the fairest and soundest trees, is best, and does (for the most part) direct to the proper season of interring, according to institution.

Nature herself who all created first,
Invented sowing, and the wild plants nurs’t:
When mast and berries from the trees did drop,
Succeeded under by a numerous crop.

Yet this is to be consider’d, that if the place you sow in be too cold for an autumnal semination, your acorns, mast, and other seeds may be prepared for the vernal by being barrel’d, or potted up in moist sand, or earth stratum super stratum during the winter; ... Chuse a fit piece of ground, and with boards (if it have not that position of it self) design it three foot high; lay the first foot in fine earth, another of seeds, acorns, mast, keys, nuts, haws, holly-berries, &c. promiscuously, or separate, with (now and then) a little mould sprinkled amongst them: The third foot wholly earth: Of these preparatory magazines make as many, and as much larger ones as will serve your turn, continuing it from time to time as your store is brought in. The same for ruder handlings, may you also do by burying your seeds in dry sand, or pulveriz’d earth, barrelling them (as I said) in tubs, or laid in heaps in some deep cellar where the rigour of the winter may least prejudice them; and I have fill’d old hampers, bee-hives, and boxes with them, and found the like advantage, which is to have them ready for your seminary, as before hath been shew’d, and exceedingly prevent the season. ”

Don't you just love the poem in the middle there?

Of course our technique has improved since the 1600's.  In the past I have put the seeds in the fridge, and I have colleagues who also use this cooler method.  But, I like to take advantage of natural winter chilling to germinate seeds.  It is so much easier than bagging seeds up, putting them in the fridge, and then remembering to sow them later on.  Why artificially create what nature already offers?  Also, there is some evidence that the diurnal changes in temperature may positively promote germination. 

Last winter, I filled the cold frame with 4 inches of growing substrate and sowed several different species directly into that media.  We were traveling for the holidays, and I was worried about the seeds drying out too much in individual cells while we were gone. This method worked well.  I got good germination on most species, but sowing en masse made it difficult to separate them when planting up later on. 

The cold frame last winter. Old, used labels that were headed to the trash became block edges for different species.

This year, I sowed the seeds into trays to make it easier on me.  We didn't travel over the holidays, and I was able to more closely monitor their moisture levels.  Because I knew I would run out of room in my cold frame this year, I built a small low tunnel frame where I can cover a 4 × 8 ft area with floating row cover supported by the same hoops I used to cover my vegetable beds.  The floating row cover provides just enough protection to keep the frost off. 

In my rush to get the seeds sown and because a few of them of them still have fluff or chaff on them, I don't fret much about trying to get one seed per hole.  I can always transplant or move seedlings around later in their cells.  I will note that I flame some seed like Liatris, Andropogon, and Asclepias in a bucket to get the fluff off the seed. 

I am fascinated by seeing the differences in germination time, even for some species in the same family.  For example, Penstemon tenuis germinated fairly quickly within a week while Penstemon digitalis took a month from sowing to start showing cotyledons. 

Penstemon digitalis takes longer to germinate than Penstemon tenuis (not pictured).

Winter is a good time to clean out the fridge for seeds and go through old boxes.  I had hoped to be done by now with my winter perennial sowing, but I keep finding more species that I saved earlier this year to sow now.  For most of the country you should still have a little time to get seed that need stratifying sown outdoors or just use the fridge method I mentioned earlier. Either way is sure to result in more plants this year for your garden.

Ipomopsis rubra was another fast germinating species. I transplanted them out shortly after this photo.

Amsonia hubrichtii emerge from their cigar-shaped seed.

The thread-like cotyledons of Lilium formosanum

A Snow Day at the JC Raulston Arboretum

This is post 1 of 12 of a series I’m doing this year reflecting back on some of my favorite plants from visiting the JC Raulston Arboretum while attending graduate school at NC State in Raleigh NC. Check back next month for more.

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It has been seven years since I left graduate school in Raleigh NC. At the time it was a challenge living in an apartment without a garden. Even though I had 100+ plants on my balcony in containers, I missed being able to roam through a garden and observe the minutiae of the day-to-day happenings in the plant world.

The JC Raulston Arboretum became a garden away from my home garden for me. It was started as in 1976 by the late Dr. JC Raulston as a living laboratory for students and the North Carolina nursery industry, and it has blossomed into one of the top university botanic gardens in the United States. (If you want to learn more, read Chlorophyll in His Veins by Bobby Ward). I visited countless times and amassed probably over 10,000 photographs over my time there. So, in what has started as another sedentary year for us with no travel in sight, I’ve decided to plunge into my photographs to share some of my favorite plants each month from this incredible place.

One of my most memorable experiences visiting the arboretum was my first winter in Raleigh. When I left Tennessee to head to North Carolina, I assumed that I would never see snow again. But, in early 2009, 3–7 inches fell on a Tuesday. My official measurement at the arboretum with a ruler was 4 inches.

I remember the day vividly because that Tuesday was January 20, 2009, and Barack Obama was being sworn in as president. Being an independent and political junkie, I had the news going on in the background as I labored on graduate school projects. My desk was right against the window so I would shift screens between the TV, the computer, and glancing up to see the snow flying outside my window. Thinking back now, it was nice to see so much white and peace in a world where red and blue seem to dominate.

Around lunch I headed over to the arboretum once the snow had abated to enjoy the winter wonderland, and I spent at least two hours roaming the collections. Below are some of my favorite photographs and plants of the day.

I loved seeing the screen garden with where the leaves on Agave and Yucca became needles emerging from white pincushions.

You can really appreciate how well the Agave captured snow on this Agave parryi ssp. parryi var. truncata J.C. Raulston’.

I loved seeing how each blade of these Yucca aloifolia were laden with the snow.

The snow highlighted structure of trees. One that was particularly striking was Firmiana simplex. The dull viridian trunk resembled a dinosaur leg.

And, how can you not love this cinnamon-colored bark on Stewartia sinensis var. sinensis?

One plant that I fell in love with the first winter was Salix ‘Flame’, and it is still at the top of my list of favorite plants. I find myself gravitating to colorful stems for winter color, and this orange-twig willow had such a rich, warm hue.

Going through these photographs I realized I had forgotten about Acer negundo ‘White Lightning’! Most consider boxelders trash trees, but wowzer, these stems shine against the white and brown of winter.

And, one cannot forget about the finicky red-twig dogwoods. Here the thin twigs of Cornus sanguinea ‘Midwinter Fire’ glow bright.

In the Japanese garden the black lines of Phyllostachys nigra pop against the white.

The snow adds another dimension to this Tsuga canadensis ‘Curley’. The laden branches look die cut.

The needles of Pinus virginiana ‘Wates Golden’ glow with the afternoon sun.

Osmanthus heterophyllus ‘Goshiki’ was one of my favorite broadleaf evergreens in the garden. The sun-splashed foliage was particularly effective in the winter.

And, then of course were the flowering plants on my snowy visit. Another winter favorite I learned about at the JC Raulston Arboretum was Edgeworthia chrysantha ‘Winter Gold’. At the time paperbushes were fairly unknown, but I would say that their popularity has really grown in the past 10 to 15 years. You can see some flowers opening yellow in this image.

Many members of the witchhazel family flower in winter. Here the buds on the interesting hybrid ×Sycoparrotia semidecidua begin to pop. They are small, but they somewhat resemble exploding figs.

Hamamelis vernalis was also in full bloom on this snowy day and their sweet smell—though some say sickly sweet—perfumed the air.

Looking back I realize just how many of my winter favorites I learned from this garden. Here is Chimonanthus praecox ‘Luteus’. It, too, has an incredible sweet fragrance that can travel far in the garden. Often I smell this shrub before I see it.

Growing up, I always admired the deciduous hollies on the fencerows back in Tennessee. I think they look best with some snowy adornments.

I was tickled pink seeing just how colorful these Symphoricarpos × doorenbosii Magic Berry were.

It is always fun to see how seedheads interact with snow. Here Rudbeckia fulgida ‘Viettes Little Suzi’ appears to be wearing white toboggans.

Serendipity. The syncarps on Liquidambar styraciflua ‘Frosty’ look a little… well… frosty. In case you’re curious about the cultivar name, this selection has variegated leaves.

Even the fading flowers of Schizophragma hydrangeoides ‘Moonlight’ were effective snowcatchers.

Yes, it was a truly memorable day walking through the JC Raulston Arboretum after a good snow. One last photo of the White Garden covered in white. Little did I know at the time that Karen and I would get married here in seven years.