Fall at the Dallas Arboretum

When I moved to Texas in 2014, one of the first places I wanted to visit was the The Dallas Arboretum & Botanic Garden in October. I had seen mesmerizing images of pumpkins used to create spectacular villages online from friends who had gone. During my first summer in Texas, I met SFA alumna Jenny Wegley who is the vice president of horticulture operations at the arboretum. I told Jenny that I was interested in coming to visit later that fall and wanted to bring students along. She said we were welcome to come and to give her a heads up when we made our way to Dallas.

A few months later, a handful of students and I left Nacogdoches around 6 am to get to Dallas as early as possible. We first headed to the Pecan Grove to meet up with Jenny before the big crowds of people arrived. Pecan Grove, where the core of the autumn display is housed each year, was covered with pumpkin pointillism. Jenny told us that some years 90,000 pumpkins are used to decorate the arboretum, and each year different designs are used to enchant both new and returning visitors.

The pumpkin display is concentrated in Pecan Grove, an open area that allows the gardeners to install whatever suits their artistic pallet.

What a foundation planting for this pumpkin house!

A close up of the wall of squash reveals the delightful diversity of textures and colors from the cucurbit family.

Our crop of students standing amongst a crop of pumpkins. Even Jenny Wegley (third from right) was an SFA grad from back in the day.

The staff at the Dallas Arboretum were hard at work making sure that the displays were “stuffed” with enough pumpkins.

I found these pumpkin garlands adorable! They were made using wire and had ornamental corn hung from them, too.

A river of steel blue pumpkins meanders through a tapestry of orange.

Piles of cucurbits surrounded by vining ornamental sweet potatoes created the illusion of a pumpkin patch.

After we left Pecan Grove, we walked to see other parts of the arboretum. Along the way we saw other places where the gardeners had integrated pumpkins into the landscape displays.

Pumpkins were used as edging along side these beds of Pachystachys lutea and Strobilanthes dyerianus.

Pumpkin edging fades into pumpkin piles here in front of Hamelia patens and Manihot esculenta ‘Variegata’.

These pumpkin cairns add a pop to this bed of Tagetes.

I liked how the white pumpkins picked up the hints of white in the fading Begonia petals.

And, then other parts of the arboretum were planted for fall color.

This alley of juvenile trees was planted with Tagetes and Ipomoea for fall color.

This bed featured quite a contrast between the yellow Chrysanthemum and Acalypha wilkesiana ‘Kona Gold’ and the purple Torenia.

We saw Lespedeza thunbergii subsp. thunbergii 'Little Volcano' at the arboretum. I love this fall flowering shrub; for weeks the branches are covered in lovely magenta flowers that are held amongst glaucous blue leaves.

My first trip taking students to the Dallas Arboretum was a wonderful time. And, while most of us can’t have 90,000 pumpkins at our homes, I hope that some of these photos have helped to inspire you to be a bit creative with how you create your autumnal displays!

September at the JC Raulston Arboretum

This post is 9 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.

This week we left September behind, and I had fun sorting through photographs from the JC Raulston Arboretum. Each year when I went out to take these photos, school would have just started back, and it was a nice break to get out in the garden and witness the shifting seasons from summer to fall. Enjoy these photos and great plants from my time in Raleigh.

Passiflora 'Purple Haze' blooms with its sensational flowers. I love how Passiflora are a host to Gulf fritillary that we see buzzing our flowers in fall.

I was delighted to see Symphytum × uplandicum 'Axminster Gold' at the arboretum in the lath house. I figured it would burn in the south, but the foliage was quite clean and colorful.

Callicarpa americana 'Welch's Pink' is a wonderful pink fruited selection of our native beautyberry that was discovered by SFA graduate Matt Welch. The JCRA website notes that seedlings tend to come true to type, indicating this mutation is likely stable and not the result of hybridization.

Butterfly gingers smell spectacular throughout the summer, and in September their bloom begins to wind down as we head into fall. Here, the coral colored flowers of Hedychium 'Elizabeth' are still hanging on.

I loved watching the flower bud of Musella lasiocarpa develop over the summer at the arboretum. It looked so freaky with all the sheathing leaves until…

…it exploded into flower. Musella lasiocarpa really is an amazing ornamental banana with its giant inflorescence.

The arboretum featured a collection of rainlilies like this Zephyranthes ‘Bangkok Yellow’. I always delighted in seeing them bloom, roughly five days after a rain.

One day, I noticed that this Zingiber mioga 'Silver Arrow' had some fallen flowers at its base. I knelt down to investigate, and I discovered that these were actually flowers emerging from the plant! It was such an interesting adaptation seeing the blooms at ground level.

Here’s a close up of the flowers of Zingiber mioga 'Silver Arrow' that emerged from the ground.

If you are looking for variegated tropical foliage, Curcuma petiolata 'Emperor' fits the bill. It looks like it has been streaked with a white paintbrush.

Most people know Chlorophytum as the variegated, low growing spider plant. But, I loved this upright Chlorophytum colubrinum that sported flowers in autumn.

How can you not love the smoky pink and teal flowers of Polinathes (Agave) howardii? It is such an unusual color combination to see in a tubular flower.

I admired the voluminous inflorescences of Kniphofia rooperi. This species is a later flowering form of red hot poker.

Rhodophiala bifida is a bulb I have gotten to know well after moving to Texas. Oxblood lily blooms after our first rain in autumn, usually as a herald to the emergence of Lycoris.

Lycoris albiflora emerges from herbaceous froth in the white garden at the arboretum.

The Warmth of Tickseed Sunflower

The air was chilly outside the mornings this week, so chilly that I saw my breath. However, there is still enough residual heat from the summer radiating out of the ground. That means I’m still in shorts even though the thermometer read below 50F. I love this time of the morning when the sun is just starting to warm the autumn landscape.

At a distance I see the flowers of Bidens aristosa beginning to shine with the breaking of the day. I wanted some color at the base of the willows we planted along our property line. So, I welcomed tickseed sunflower as an herbaceous layer under the growing trees. I should add another reason I brought it home was because Karen loves yellow flowers.

A glance down the line of Bidens aristosa

After we moved into our new house in August four years ago, I noticed this native growing in a spot along the roadside. One day, the blooms vanished when the highway crew mowed their end-of-season cut. So, I stopped and dug up a plant that looked like it still had some life to it. That one plant became hundreds that now grow along this western property line that runs almost north-south. I never expected them to spread so much within such a short time, but I suppose with other common names like bearded beggarticks I should have anticipated this ruderal’s ability to find purchase in other locales. Bidens are named for the two teeth-like (bi- meaning two, and -dens meaning teeth) projections on the seed that aid dispersion and cause the seeds to act like ticks on clothes and animal fur.

A close up of Bidens aristosa flowers. Doesn’t it just look like a happy color?

From my vantage in the morning the flowers glow. The effect is lost a bit once the sun traces the sky; once the sun is behind them, the gold rays don’t pop as much with the sun to their backs. However, I do hope our neighbors enjoy when they are lit by the western sun.

The plants tend to not start flowering heavily until the end of September when we reach short days. In years past I’ve noticed one side had more blooms than the other. I suspected our security light was the reason why. However, we had that turned off to help reduce interference with birds and bugs, and the numbers of flowers on either side are more equal this autumn.

This weekend once the day had warmed, I stood and watched the frenzied activity from all kinds of insects on tickseed sunflower. Gulf Fritillaries, American Bumble Bees, and Monarchs were the easiest to spot. I should note that The Xerces Society reported that this species is very good for serving as a nectar source for Monarch butterflies as they travel south. This reference reported 1893 Monarch observations, the most of any plant for the southern plains!

The show doesn’t last too long. We’ll get to enjoy Bidens aristosa for about a month before the plants start going down. But, for now they are a welcome sight and warm the garden with color as the season gets cooler and cooler.

A Peachy Keen Lycoris

This week has been pleasant for mid-September.  It is rare this time of year for us to be cool and cloudy during the day without the help of a cold front. I thank Hurricane Nicolas for bringing us a change in the weather.  We were forecast to get 2 inches of rain, but only a quarter of an inch fell.  At least the clouds and breeze kept it in the low eighties for a few days.

Such weather is perfect for admiring the emerging scapes on a lovely peach-colored Lycoris in my garden.  My starts came from the Smith County Master Gardener bulb sale that’s held every fall in Tyler, TX.   The name on this plant is a bit muddled. So, I reached out to Greg Grant who is the extension agent for Smith County to get his take on them.  

Greg said that he was the source of this particular cultivar for the sale.   His clone has gone by the names Lycoris × elsiae and Lycoris carnea over the years, but the name Lycoris × albiflora ‘Dorman’ is the most accurate name currently.  Greg said that his plants came from Cleo Barnwell of Shreveport, LA who got them from Sam Caldwell, a well-known Lycoris breeder who lived in Nashville, TN.  

Lycoris × albiflora ‘Dorman’ emerges for fall in the garden.

I like to throw Lycoris × albiflora ‘Dorman’ into fall bouquets. I’m skimping until I have a few more scapes to use.

No matter the name or the source, this Lycoris is a beautiful addition to the late summer and early fall garden.  It starts blooming about three weeks ahead of my Lycoris radiata. My scapes have doubled from four last fall to nine this year, and I feel comfortable the plants have reached a size for dividing.  It’s also time to find a better spot for them.  I’ll be honest.  When I first got the tunicate bulbs, I just threw them in a perennial bed.  

A close up of Lycoris × albiflora ‘Dorman’. The flowers open more pink and then fade to a peachy white.

I’m contemplating where to put them to create a good plant combination to play off the color. Siting for contrast doesn’t feel right because the flower has hints of white that fades through butter, peach, and pink. So, I find myself looking more for color echo. I’ve been scratching my head looking around my home garden for perennial candidates but finding none at this time of the year. Then, I realized the flowers are the same color as the flowering Muhlenbergia reverchonii that we just planted this past spring in the gravel garden at school.  I don’t have any yet at the house, but it’s now on my plant wish list to pair with this Lycoris for a peachy-keen color echo.  

A photo of our gravel garden backlit by the afternoon sun. Muhlenbergia reverchonii (in the upper right) would provide a perfect back drop for Lycoris × albiflora ‘Dorman’ flowers emerging amongst the panicles.

August at the JC Raulston Arboretum

This post is 8 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.

Of course, it’s September now, but I’ve been sorting through photographs the past few weeks that I took in Augusts past at the JC Raulston Arboretum. I moved to Raleigh, NC in August of 2008, and the arboretum became a home away from home. I would spend some of my first evenings walking around the garden to learn plants that grew well in the area. Each August thereafter would still have that same feeling of learning and exploration as a new school year began. So, I hope you enjoy learning and exploring a few of my favorite plants from the JC Raulston Arboretum from one of the hottest months of the year.

One of the first photographs I took after moving to Raleigh was this looking down shot on a Yucca rostrata, a tough plant that can become a focal point in the landscape. It starts as a skirt of lanceolate leaves and then elongates towards the sky over the years, leaving a thick stem in its wake.

August was the month that I started noticing the warm orange color on Salix ‘Flame’ that would become prominent over the winter months once the foliage dropped. Here you also notice the smoky color of the leaves.

In August the buds on Rostrinucula dependens would start to elongate before flowering a lovely pink.

I hate kudzu for its invasiveness, but the variegated ‘Sherman’s Ghost’ on the back patio created nice shade. A tough spot deserves a tough plant I suppose.

Years ago, I saw a curious vine loaded with red samaras and yellow flowers at Callaway Gardens in Georgia with no idea of its identity. At the arboretum I learned it as Heteropterys glabra, or redwing.

A close up of the beautiful fruit of Heteropterys glabra

Another amazing vine I saw at the arboretum was Mucuna cyclocarpa, or purple jade vine. I love members of the bean family that have incredible flowers, and this new-to-me vine wasn’t an exception. If you grow this species, just be aware that some have an allergy to touching the hairs on the plant.

In the Lath House at the arboretum, Hydrangea involucrata ‘Wim Rutten’ Blue Bunny(TM) bloomed well into August with its billowy lacecaps. This Hydrangea supposedly blooms on new wood, a plus for areas where winter bud damage is an issue.

Many geophytes would start flowering after summer’s crescendo as witnessed here by the geophyte border.

One of my favorite bulbs for August is Lilium formosanum. My friend Jimmy Williams told me years ago that there are few plants that reach such height in the middle of summer and bloom so effectively as this lily.

Lycoris or spider lilies would start popping in August. I loved the pink-to-purple-to-blue fade on this Lycoris sprengeri.

A new Lycoris species to me was the cream-colored Lycoris anhuiensis. I quite liked how it was planted to emerge through this groundcover of Sedum emarginatum ‘Eco Mt. Emei’.

The star-shaped, two-toned flowers of Gladiolus 'Flevo Kosmic' were out of this world!

The sweet smell of Hedychium flowers is so welcome in August. They remind me of swimming in our pool back home in Tennessee where the fragrance would waft across the water in the evenings. ‘White Starburst’ has a beautiful spiral of flowers atop 5–6 foot stems.

I really didn’t pay much attention to turk’s cap when in Raleigh, but now that I live in Texas I see it everywhere. It’s a durable, tough, native perennial that attracts Ruby-throated Hummingbirds. This clump is ‘Big Momma’, a cultivar developed by my friend Greg Grant.

A close up of the flowers on Malvaviscus arboreus var. drummondii 'Big Momma'

I was blown away when I saw this Fuchsia ‘Sunihanf’ Angel Earrings® thriving in the lath house because this genus doesn’t do well in the south at all. This cultivar is much more heat tolerant and is certainly on my wish list for trying in Texas.

I’ve written before about my love of Titanotrichum oldhamii. In the lath house this gold woodland foxglove was thriving and starting to bloom for fall.

This sheet of flowers on Sedum ‘Pure Joy’ is… well… pure joy.

A Hint of Autumn from Hyptis alata

The last Saturday in August was one of those rare cool summer days.  The temperature didn’t break 90F, and I was actually able to stay in one shirt instead of sweating through three or four.  It was the first hint of fall, albeit faint and barely whispered by the clouds that kept the sun off my back and at times drizzled enough rain to wet the ground.  There’s something about petrichor mixing with the bleached foliage of summer that smells like autumn.  

Fall plants are responding to the shift in the season.  The blackberry floricanes that were loaded mere months ago are now withered, and the cool day was an opportune time to clear them.  My first Lycoris radiata emerged quite early this week, and nearby, fall perennials like Symphyotrichum lateriflorum ‘White Lovely’ and Solidago rugosa ‘Fireworks’ are starting to flower like they do every year around this time.  

A new perennial that I’ve added to my garden that begins to enchant me in these late days of summer is Hyptis alata or clustered bushmint.  My genetics came from Mark Tietz of Wildscapes LLC in east Texas, but my introduction to the species was driving to Houston years ago.  I can’t quite remember the reason for the trip, but I do remember seeing these little cream-colored balls on stems rising from the highway ditches.  It looked like someone had stuck cake pops on a stem.

Hyptis alata is a species that hugs the coastal plain. It was quite at home in this cajun prairie in Eunice, Louisiana a few years back.

A few Octobers ago, I again encountered Hyptis alata in the cajun prairie in Eunice, LA . It was here that I realized the orbs were a great contrast to the linear grasses.   So, when Mark gave me a couple plants, I already had an idea of what to expect from this species.

Hyptis remind me of the orbs of Eryngium.  However, instead of white balls of flowers concentrated at the top, a single stem of Hyptis alata sports a dozen or more flower clusters held oppositely a few inches from the stem as it rises in the garden.  And, with 20 to 30 stems, the layering of these dots is like a pointillism painting.  

As the flower clusters continue to grow in size, they begin to resemble mini-cake pops.

I like the contrast of the white Hyptis alata with the black seedheads of Baptisia alba.

This native has an overall white appearance in the garden, which is welcome at a time when blacks and browns are begin to accumulate.  The white color comes from the combination of the spotted white flowers, the light green sepals that remain after the flower falls, and hazy-colored bracts under the flower cluster.   Once flowering finishes in another month or so, the orbs will turn more green and then fade to a dark umber. In this state I will enjoy Hyptis through winter until spring cutback.  

Hyptis alata looks lovely in the winter. The seed heads are quite persistent.

Now that I’ve had it for a few seasons, I’ve learned to cut it to the ground in mid-spring to help delay the onset of flowers and keep the height in check.  It can flop from the breezy rains we get in autumn. I’ve also learned that it attracts pollinators a plenty. I’m amazed that my photos don’t show any of the black wasps that go nuts over this plant. I usually have 5 to 10 buzzing it.

Some of you may be wondering about hardiness.  This gulf coast species is a bit frost sensitive.  This past spring after it had emerged we had a night that dipped below freezing.  A day later the foliage looked a bit burned while all the other perennials in the bed remained untouched.  Thus, I’m not sure how well it would overwinter further north.  It can be a bit seedy, which increases its chances of returning, but in my garden keeping the soil covered with vegetation seems to prevent most from germinating.  It’s only when there is bare soil that they find a start, and they are easily weeded out.

Yes, there’s a hint of autumn in seeing Hyptis alata in flower. It won’t be long now.

Direct Sowing the Fall Garden

I’ve always thought of August as the start of a new year. While I suppose that living on a school calendar for some thirty years has engrained that into me, there’s more to that feeling than just the return of classes. Change is in the air. Summer is waning, and the days are palpably getting shorter. It’s time to begin planting the fall vegetable garden. As a young gardener who experimented around with season extension, I realized that the crops that I was sowing now would live on into the spring. And, that really to begin planning next year’s garden I had to begin in late summer. It was often time to start clearing out warm-season crops that were finishing up their production anyway. So, yes, it does have the feel of a new chapter beginning.

For us in east Texas, there’s about 90 days left until our first frost, so plantings are usually intense for a month trying to get everything started and in the ground to be able to overwinter. I typically start direct seeding in late August, so I thought I would share some techniques and cultivars that I’ll be direct sowing over the next few weeks.

Mustard and Collard greens

Even though mustard and collards are separate species, I’ve grouped them together because I start sowing these greens in late August. Growing mustard greens were a Tennessee tradition for our family. I hated them at first, but once I planted them in my own garden, I quickly gained a taste for this classic southern crop.

Collards came to me later in life. I first tasted collards at the Old Salem Tavern in Old Salem, NC. They tasted delicious flavored with bacon drippings and brown sugar, so delicious that I added them to my fall rotation.

I try to time my seed sowing with a good pop up summer thunderstorm or tropical storm moving through. But, those rain events are too often unreliable, so I set sprinklers up for a week to help seeds stay moist. To evenly disperse the seeds over the growing bed, I have mixed seed with sand and then broadcasted across the bed in a criss-cross pattern. But, planting them in rows allows for easier cultivation between the plants. So, the decision is yours based on the space you have available. In either case plants live all the way through the winter here in zone 8 with yellow cruciform blossoms emerging in the spring.

You’ll hear people say let the plants experience a frost for better flavor, and there is some truth to that. Plants increase the soluble sugar in their foliage when exposed to cold temperatures, which lowers the freezing point and acts as a natural antifreeze. After harvesting, I follow my Granny’s practice of tossing the midribs and soaking the remaining foliage in salt water to rid of any pests that might still be hiding amongst the leaves.

For mustard greens, I like the classic cultivars like ‘Tendergreen’ and ‘Florida Broadleaf’. There are also ornamental mustards. ‘Red Giant’ turns a beautiful violet, ‘Magma’ has chartreuse curls and is blushed rose, and ‘Tokyo Bekana’ has a golden hue to it.  

‘Magma’ mustard erupts in the fall with blushed leaves and chartreuse curls.

For collards, definitely check out The Heirloom Collards Project for old time varieties. ‘Alabama Blue’ has lovely steel blue foliage with purple petioles. ‘Variegated’ is another fun cultivar to grow because some individuals in the population will have green and white leaves.  

One year, I had ‘Alabama Blue’ collards seed into some tall grass. I could identify it by its purple petioles.

Peas

Peas were another crop that I hated until I grew it. The truth is I didn’t know what a good pea was. Most of the peas I had from the store were very mealy and had a horrible texture. But, one year on a whim, I tried some English peas from our Sprout garden, and I was blown away by the flavor. They were as sweet as candy.

Since then, I have dedicated a couple beds at home to growing peas both in the fall and the spring. I struggled with seed germination until I realized that my plants were succumbing to a fungal wilt. Since then I have only grown disease resistant varieties like ‘PLS 595’ and ‘PLS 141’.  I should add that I sow the seed densely. It seems counter-intuitive to space them close and not thin them, but the recommendation has worked thus far.

While I have used sapling stakes, I have appreciated the consistency with nylon support held by a T-post and electrical conduit frame. The conduit is fed through PVC T-joints that rest on top of posts. The vines are rambunctious growing towards the low sun; thus, I run cotton twine every foot or so to help encourage them to climb their trellis. They will tank with the first frost, but I rip them out and plant something cold tolerant like spinach in their wake.

Carrots

There is nothing like a fall grown carrot. Seed sown in early September will be ready around early November, but if you let them sit in the soil for another month or two, they will sweeten, again due to sugar acting as a natural antifreeze. That’s a trick I learned from Eliot Coleman, and while we don’t experience quite the extended cold they do further north, I still notice a different between fall and spring carrot flavor.

When sowing seed in late August/early September, moisture is crucial. The seeds have to be watered well every day for six days.  SIX DAYS. I cannot stress that enough in the south. To aid in moisture retention, I will often cover them with floating row cover and check daily for any sign of emergence on the seed. Note that as you sow later into fall, the time to harvest increases. Carrots sown in late November will be ready to harvest 3-to-4 months later.

My favorite cultivars include the orange ‘Napoli’, the crimson ‘Atomic Red’, the violet with orange center ‘Purple Haze’ (although seed has been hard to find of late), and the creme-amber-tangerine mix ‘Rainbow’.

Floating row cover held down by T-posts is an effective cover for reducing water evaporation from the soil to aid in carrot seed germination.

I’m super excited to welcome the fall garden back into production. Best of luck direct sowing seed for these crops this fall, and happy new year for all you cool-season gardening aficionados!

The Scott Arboretum Part 2

This is Part 2 of 2 of a series looking back at our June trip to visit The Scott Arboretum of Swarthmore College. To read part 1 about our morning time there, click here.

Karen and I left The Scott Arboretum for lunch and made a pit stop to see the gravel gardens on the traffic circle near campus. I was very intrigued to see these plantings because my students and I had just installed a gravel garden at SFA. These gravel gardens were developed to help slow traffic, increase the beauty of the area, and be low maintenance since the grit reduces weed seed germination.

Cassian Schmidt, director of Hermannshof Garden and leader in designing for plant stress to minimize maintenance, consulted on the project when he taught a workshop on the subject a few years ago for the arboretum. It sounds like they took an approach similar to what we are doing, start small and then expand outward. You can read more about The Scott Arboretum’s gravel gardens here, here, and here, and they have an educational video on the subject as well.

The center planting in the traffic circle features herbaceous perennials like Allium ‘Ambassador’ and Salvia × sylvestris ‘Blauhügel’ around Juniperus virginiana ‘Corcorcor’ Emerald Sentinel and Gymnocladus dioicus ‘Espresso-JFS’ Espresso. Research has demonstrated that people slow down when driving through roundabouts if trees are included in the planting mix.

A close up of the herbaceous layer with Salvia × sylvestris ‘Blauhügel’ and Allium ‘Ambassador’ in bloom

The beds surrounding the roundabout featured more perennials. The round mound Baptisia had already finished, and Asclepias tuberosa and Coreopsis verticillata 'Zagreb' were just beginning to bloom.

Here the spacing between the gravel garden plants is better seen. Again, Asclepias tuberosa and Coreopsis verticillata 'Zagreb' are in bloom, and I spy Liatris and Symphyotrichum rising for later in the year.

The island beds featured a mix of even shorter plants like yellow-flowering Sedum and pops of pink from Phemeranthus calycinus.

Back near the entrance of The Scott Arboretum was one of the first gravel beds planted with Sedum, Stachys, Allium, and various other perennials. Gravel gardens have less maintenance because the grit reduces weed germination and establishment.

After lunch, we headed back to the arboretum to meet up with Chuck Hinkle and Lars Rasmussen to tour the green roofs. We had a bit of time before our scheduled meet up, so we wandered toward the south end of campus while checking out more great plants.

A photograph of the back of the Cunningham House, which houses the main offices for The Scott Arboretum. One thing I love about these beds is the effort to echo the burgundy and brown colors of the building with the plants.

A combination behind the Cunningham House that I loved was Asclepias tuberosa and Physocarpus opulifolius Tiny Wine.

While I adore our native dogwoods, many of the Asian Cornus kousa just seem to have more oomph when in bloom, and the bracts last longer. This specimen is ‘Greensleeves’, a Pennsylvania Horticultural Society Gold Medal winner.

This Acer palmatum ‘Manyo-no-sato’ had a wonderful two-tone color to the foliage, burgundy with a lighter green.

Behind the Cunningham House are some of the largest Ulmus americana that I’ve ever seen, partly because they are treated regularly for Dutch elm disease. Most of these giants have been lost throughout the rest of the country.

Dr. Denny Werner’s new ‘Flamethrower’ Cercis canadensis was looking lit at the arboretum.

Stewartia × henryae, a hybrid of Stewartia pseudocamellia and Stewartia monadelpha, was just beginning to flower with its classic Theaceae-type blooms.

Hamamelis mollis ‘Gold Edge’ lived up to its name with the light brush of variegation on the outside edge.

Finally, after photographing every plant on our walk there and probably seeming like forever to Karen, we arrived at Alice Paul and David Kemp residence halls on the south side of campus. These dorms both have green roofs on their tops. In 2008 when I was an intern here at the arboretum, I was amazed to see these forms of green infrastructure. I learned about how they cool buildings, help roof membranes last longer, slow rainfall, and provide habitat for creatures. Years ago when I was a wee intern, I had heard these were a thing that existed, but when I climbed out on top, I realized that yes, people can grow plants on roofs. I still had that same feeling when we emerged to see these carpets of green again 13 years later.

Chuck and Lars talked more about how they had elevated parts of the substrate to be able to grow more species besides just Sedum. Green roofs are classified as either extensive (3–6 inches of substrate) or intensive (greater than 6 inches of substrate). And, in case you can’t keep them straight, I teach students just remember that intensive is the deeper because with deeper soil comes more plants and thus more intensive cultivation. While these residence halls were designed to be able to support green roofs, many buildings can’t hold enough growing media for intensive cultivation. Thus, creating berms or slightly elevated areas helps diversify the plantings. They also talked about how one year they had a really bad grub problem. Crows had actually come in to start eating them, and in the process, part of the green roof planting had holes in it. You can learn more about the planting process here.

Billowy sedum under billowy clouds

On parts of the green roof, the depth of the substrate has been increased to allow for perennials like Asclepias tuberosa and grasses to be able to survive.

On a lower tier of the green roof, they even had a bee hive.

One microclimate that Chuck and Lars showed us was this back corner of the green roof that is shaded from the western sun. Here, grasses have become more prevalent because the shade helps reduce moisture evaporation.

After we were down off the roof, Chuck offered to show us some wood handiwork from some large trees that had to be taken down. We walked along a wooden path to find a council ring that had been hewn from massive trunks. I joked that this was quite the “retreeat”.

Some of the impressive seats carved out of giant tree trunks.

The pathway to the council ring

We then headed back up to the main part of campus. I wanted to see the Isabelle Cosby Courtyard as the gardens within this space were planted with a nice assortment of plants. The courtyard was a folly that had pillars and arches built to resemble a ruin since a building used to be there.

Along the way we spied this Schizophragma hydrangeoides ‘Moonlight’ climbing up Clothier Hall on campus. This cultivar is beloved for not only its beautiful flowers but also the silvery foliage.

Just south of Cosby Courtyard we found this mass planting of Phlox ‘Minnie' Pearl’ amongst scattered Hydrangea arborescens. This cultivar is one of my favorite spring flowering Phlox for its clear white flowers. It stays low and slowly spreads.

This pair of espaliered Ginkgo biloba ‘Saratoga’ on the south side of Cosby Courtyard are quite something to behold. I love how the gardeners are creating the appearance of the branches joining together.

A close up of the espaliered Ginkgo biloba ‘Saratoga’

In part 1 I shared how Clematis climbed roses in the garden. Here’s another example of using a woody shrub (Itea virginica) to support a Clematis (‘Danuta’).

Karen provides scale for this massive Cercis canadensis ‘Ruby Falls’, another of Dr. Denny Werner’s creations. It is a weeping form of redbud with deep maroon coloring on the new foliage.

This plant is not poison ivy! Rhus aromatica ‘Gro-Low’ is a great native shrub groundcover, and it was used in Cosby Courtyard plantings. It has spectacular fall color, too.

And, we found one of my favorite magnolias in Cosby Courtyard. Magnolia macrophylla var. ashei is a native to Florida but is cold hardy all the way up to Chicago. It is different from Magnolia macrophylla because it is very precocious and blooms in only a few years from seed.

Eventually, we made our way to the amphitheater where graduation is held every year before we headed back to our car. It’s one of the most beautiful landscapes I’ve ever seen. This iconic hardscape was designed in 1942, and when I visit, I feel like I’m standing in some ancient ruin where the trees have long since taken over to create a forest cathedral.

Heaven. Wouldn’t you just love to stare at this view of the Scott Outdoor Amphitheater all day?

I loved how the gardeners had sited a new Liriodendron in one of the old trunks. Growing on the shoulders of giants I guess one could say.

Leaving campus, I spied this grand Catalpa speciosa. Again, Karen provides a nice scale for size.

What I loved most about this Catalpa speciosa was the fallen art from the carpet of petals it dropped.

I started this post talking about the gravel gardens on campus, and we ended the day with seeing the gravel garden at Andrew Bunting’s house before dinner. Andrew, once curator for The Scott Arboretum and now Vice President of Public Horticulture at the Pennsylvania Horticultural Society, lives right down the road from campus. He just redid his front yard a couple of years ago to feature more plants in grit, and already the planting was filling in well. It was a nice wrap up to a fantastic day visiting one of America’s most beautiful campuses. I can’t wait to visit again.

Andrew Bunting’s gravel garden at his house Belvidere just before a storm rolled through. Many of the perennials have settled in quite nicely.

The Scott Arboretum Part 1

Part of our trip to Philadelphia in June was to see the flower show, but another reason I wanted to visit the city of brotherly love was to check in on Hailey, one of our recent graduates from SFA.   She was following in my footsteps by interning at The Scott Arboretum of Swarthmore College this summer.  This garden is very special to me because I was a summer intern there 13 years ago (Wow, that long?!?), and I have many fond memories of my time spent in this quaint area. The horticulture I learned and the people I met transformed my life.

If you’ve never heard of The Scott Arboretum, it spans across the entire 300 acre campus of Swarthmore College (I’ll add that if I interchange campus and arboretum, just know I’m talking about the same thing). It was started in 1929, and around 4000 taxa grow here. Anytime a list of the most beautiful campuses in America is published, Swarthmore is usually near the top, no doubt thanks in part to the beauty of the arboretum.  

We first visited the Cunningham House, an observatory that was converted into the arboretum’s main office, and found the beds showing their transition from spring to summer. Many of my friends that I knew back in the day still work here. We got to touch base with Claire Sawyers, the arboretum director, and Jody Downer, special projects coordinator.  Horticulturist Josh Coceano came up with his team of interns, Hailey, Julia, and Ellie.  They were freshening up the container plantings, a job that I also had as an intern. They edited a container the same way I learned, to approach it and look at the plants for anything that is off—a yellowing leaf, torn foliage, or a flower that needs to be deadheaded. It always amazed to me to see how some slight tweaks made a container planting look more attractive.  

The Cunningham House clothed in its mature plantings and seasonal flora.

A group of containers welcomes guest to the Cunningham House.

Josh talks to Julia (left) and Hailey (right) about how to edit the containers.

Hailey freshens up a Physocarpus in a container. While most people think that containers are just for annuals or perennials, the arboretum frequently uses shrubs or juvenile trees in planters.

Hailey said she and the other interns did this cool succulent and xeric planting.

I liked how these plants echoed the terra cotta color of the urn.

A few other plants around the Cunningham House caught my eye. These Salvia nutans looked lovely en masse.

Most Deutzia are white, but this large Deutzia × hybrida ‘Magicien’ was blushed pink and looked spectacular in full bloom.

I love Stachyurus for their winter blooms, but if they also have variegated foliage like this Stachyurus chinensis ‘Magpie’, it’s even better.

Claire said the rose garden was looking the best that it would for the year, so we headed there first. The Dean Bond Rose Garden was established in 1956, and in the years since graduates have been able to choose a rose from the garden to wear for graduation. Today, it holds around 300 different roses. One of the neat shifts since I was an intern is that the garden was redesigned to replace the rose monoculture with a more diverse planting. More disease tolerant rose cultivars were also chosen to reduce the need for spraying. These slight cultural shifts now help the gardeners to manage this space organically.

The Dean Bond Rose Garden plantings have diversified since my internship at The Scott Arboretum.

Salvia,…

… Geranium,…

… and Lavandula diversify the rose garden plantings away from the monoculture it once was and make it harder for pests and disease to sweep through the population.

I’ll be honest. Roses have never been my thing because of all the care and upkeep they require, but I would love to have a planting of disease-resistant ones like you see here.

I so wish that we could grow these lollipop ‘Globemaster’ Allium in the south. Alas…

My friend Jeff Jabco who is Director of Grounds at Swarthmore stopped by to chat about the rose garden. Jeff is also current president of the International Clematis Society, and he has helped to introduce more new varieties to the garden. Many are dwarf clematis that are slowly making their way into the market for small patios and windowbox planters. He even helped coordinate The Scott Arboretum starting a Clematis cultivar trial with Chanticleer and Longwood Gardens in 2014 to evaluate new varieties coming out of Europe. The faint baby blue ‘Dutch Sky’, which caught my eye the minute we entered the rose garden, was each garden’s number one performer. It was covered in flowers, and I can’t wait to try this cultivar. (Here’s the current link to read about ‘Dutch Sky’, but after July 2021, it looks like this link will be the permanent place to learn about it.)

Clematis ‘Dutch Sky’ was rated the best cultivar in the trials at The Scott Arboretum, Chanticleer, and Longwood Gardens.

A close up of the light blue flowers of ‘Dutch Sky’ Clematis

Even back when I was an intern I noticed how well Clematis scrambled up the arching stems of rambling roses along the back trellis. I didn’t notice it until Jeff commented on it, but even this trellis had been redesigned. He said that since Clematis need something to cling to, they couldn’t just be smooth metal poles. Therefore, a committee helped conceptualize the trellis supports that a metallurgist then made. The poles would have metal curved into waves and small rods to help support Clematis.

Jeff Jabco shows us the trellising that was made for the rose garden to also provide support for the Clematis.

Here you can see the thin rods and wavy metal.

I didn’t realize it until later, but the waves give the trellis a nice texture.

The metallurgist also made incredible gates for the entrances to the rose garden. Notice the details on the roses and the hummingbird.

Jeff walked us across campus talking about more changes to the grounds. For example, Maxine Frank Singer Hall is a brand new building to house biology, engineering, and psychology, and the landscape around it is planted to mimic an eastern woodland habitat. They even created a stumpery on the southeast side of the building from a fallen tree.

Maxine Frank Singer Hall is sleek, stylish, and sustainable.

I love how they incorporated this fallen tree back into the landscape.

A few other shots from our trek across campus. I always make a point to stop in the Harry Wood Courtyard Garden to see if there’s any teaching scribbles left on the wall. This trip I lucked out! These slate panels are for great outdoor instruction.

‘Ryusen’ is one of my favorite Japanese maples for its weeping habit.

Every time I see this Cornus kousa 'Wolf Eyes', I swoon. It’s planted on the north side of a building to protect from harsh sunlight.

The bracts almost hide amongst the white margins on ‘Wolf Eyes’.

One of my favorite parts of The Scott Arboretum are these masses of Sporobolus that are planted in a grit mixture. These areas of campus are prone to flooding, and below the plants are cisterns that help to redirect water back into Crum Creek. Since I last visited, I like how they added the Allium and Dianthus for a pop of color.

We left Jeff and went to catch up with other gardener friends Chuck Hinkle and Lars Rasmussen who were on the north side of campus. Chuck shares my love of herbaceous perennials. He showed us nearby plantings where they had done some massings of shade perennials and Baptisia near new buildings. By this time it was lunch. They offered to show us the green roof after we ate, and they encouraged us to go catch the traffic circle.

If you want to learn more about those, then keep an eye out for part 2 that will feature more about our afternoon visit to The Scott Arboretum.

An interesting play on colors and textures in shade.

Chuck said this Baptisia 'Blueberry Sundae' did really well in the Mt. Cuba Center Baptisia trials, and they had used it on campus in different areas.

A Mystery of Crepe Murder

I have a theory about crepe murder.  It’s just a theory, but hear me out.

First, I should share that the obsession with passing judgement over those who crepe murder, what we call the annual cutting back of Lagerstroemia, has made me pause over the years.  Why have we as an industry hitched our wagon to discouraging this practice when there are far worse problems out there that demand our attention? 

A classic example of crepe murder. Note the one solitary branch left that had a bird nest in it. Butcher one life, and save another I suppose.

I’ve seen bumper stickers , I’ve seen email tag lines, and I’ve seen contests for the worst examples, all in an attempt to discourage the practice. But, I’d rather see a crepe myrtle cut back hard than see gas-fueled, water-hungry, manicured lawns; privet growing and sowing all over a back garden fence; or the blanket spraying of roadsides with herbicides or blanket spraying plants with insecticide without knowing what the pest is.

Sure, I agree that it is much nicer to see a towering crepe myrtle in its natural form not butchered back, and I teach my students so in class. 

How many crepe myrtles do you count? Most of these haven’t been crepe murdered and allowed to reach their full form.

And, they don’t even have to bloom. Look at this thing! A mighty Lagerstroemia fauriei displays beautiful bark at the JC Raulston Arboretum.

Sure, I agree that the practice can create plant health issues for this tree. Crepe myrtle bark scale hasn’t helped with that either. 

But, this species is a non-native, vigorous tree. If you’re not happy with how it has been cut back over the years, then cut it down and start all over again. It’s much harder to do that with an oak or a maple. In 10 years or so by thinning out the small branches, you’ll have a nice small-statured tree. I have corrected crepe murdered plants before, so I know it can be done.

Crepe murder is basically a form of pollarding, something that we horticulturists admire and revere in other species. Pollarding (and coppicing) are both practices that date back eons and have sustained humans in the past. And, that’s what I’ve been so curious about, the other species.  Why don’t we see them murdered?  Why aren’t we talking about magnolia mutilation or vitex vilifying? 

So, it’s a mystery to me. Why crepe myrtles? Really, I’m to believe that the reason crepe murder occurs is because crepe myrtles are the only species that people plant near their house and grow taller than they expect? Yea, right. Maybe they are murdered more because crepe myrtles bloom so well on new wood? Or, is it because crepe myrtles are planted everywhere in the south and so we are so aware of people committing this practice? Why crepe myrtles?

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When traveling through Tennessee last week I saw a possible clue to this mystery. I noticed that virtually every crepe myrtle I saw had significant winter dieback from the February freeze of Winter Storm Uri.  The tops of the trees looked like claws all curled together, and the bottoms were flushing ample new growth in an attempt to regrow.

A row of crepe myrtles exhibiting branch dieback from the cold temperatures during Winter Storm Uri.

It looks like someone braided a bunch of dead branches together at the top in these crepe myrtles.

These crepe myrtles in my hometown were crepe murdered years ago. I cut them to the ground, retrained them up as multi-trunk trees, and for years they’ve looked good. But, now after Winter Storm Uri, they don’t look so hot up top.

So, here’s my theory. I wonder if winter dieback partly resulted in the practice of crepe murder.  Hard winters killed plant tissue, people pruned them back, and then the practice just started to catch on as it became monkey see-monkey do? Perhaps it became part of the unconscious gardening calendar?  Even this year after the February freeze, I had to hack back some 30-year-old azaleas at my house to get rid of the deadwood and encourage them to regenerate.

If this past winter created these conditions, were there other cold spells that did the same? Back home in Tennessee, I frequently heard from gardeners how rough the winters of the 1980’s were, which you can read about here, here, and here. I even recall in my Master Gardener classes people commenting about how in Tennessee crepe myrtles used to not be very hardy above ground, but over the past 30-to-40 years of course with warmer winters they were better able to achieve their full form.

I really feel for people like my parents who have a lot of damage in their crepe myrtles.  I mean what is the homeowner supposed to do? We’ve been telling people for years don’t cut crepe myrtles back, or you are an imbecile.

Well, I’m here to say it’s ok if you prune these sickly-looking plants. It would take hours and hours to try to isolate all the deadwood in the trees; therefore, I believe they need to be cut down to a point and allowed to regrow. The new growth that flushes can then be trained up into a new tree-like form by removing the smallest branches. The University of Florida has a nice guide on how to prune crepe myrtles, and if you don’t feel comfortable doing it, then you can always hire a professional.

So, maybe winter damage has something to do with crepe murder, or maybe it’s a combination of factors. It is just a theory, but I hope this perspective gives you the courage to do something about your crepe myrtles if they ever look rough.