One of the problems horticulturists have is the struggle of knowing how to appropriately site and manage plants in naturalistic plantings.
One of the most powerful tools I use to help with these issues is Grime’s Triangle or the CSR theory—a framework that categorizes plants based on their competitive (C), stress-tolerant (S), or ruderal (R) strategies.
Imagine being able to look at a plant, notice a few characteristics, and immediately know how to use it. That’s the power of understanding plant strategies. For me, these strategies are more useful than simply labeling plants as annual, perennial, or biennial because they reveal more about how the plant behaves in various conditions.`
But, theory only takes you so far. So, I wanted to share with you readers five ways I apply the CSR theory at Ephemera Farm.
1. Covering the Ground with Ruderals
Ruderals are fast-growing plants that thrive in disturbed areas. I use species like Lupinus subcarnosus (sandyland bluebonnets), Nemophila phacelioides (baby blue eyes), and Streptanthus maculatus (clasping jewelflower) to cover open gaps in my garden beds in spring while I wait for plants to emerge. Later in the summer, I count on Gomphrena globosa (globe amaranth), Celosia spicata (celosia), Bidens aristosa (tickseed sunflower), and annual sunflowers to provide summer interest and occupy unplanted spaces.
Ruderals in the form of cover crops can also improve the soil and prevent weeds, especially in areas where I grow edibles and cut flowers. In late summer I will sow crimson clover and mustard greens under my blackberries. These helps to prevent weed growth overwinter.
Lupinus subcarnosus (sandyland bluebonnet) fills in gaps in the garden through winter and early spring while other plants are just starting to grow.
Later in the summer, I use ruderals to cover spots I haven’t planted yet. The plus is that many of them also serve as cut flowers.
2. Choking Out Weeds with Competitors
In the more productive parts of my property where water, light, and nutrients are abundant, weeds can take over if the ground isn’t covered. In these areas I use competitors to help reduce weed growth. I interplant Carex cherokeensis with Symphyotrichum praealtum (willow aster) and Helianthus angustifolius (swamp sunflower). Carex covers the ground early in the spring, while the aggressive growth of the aster and sunflower chokes out weeds later in the season. This dynamic pairing ensures the area needs minimal attention during the year.
The dense growth of Helianthus angustifolius (swamp sunflower) limits the growth of weeds and unwanted species in the more fertile parts of our property.
3. Stress-tolerators add diversity to lawns
Stress-tolerators are plants that survive in tough conditions. Some of them go dormant for parts of the growing season, and we can use them to add diversity to our gardens and lawns.
Many people plant Narcissus (daffodils) for bright spring color. However, the downside is the abundant foliage that remains for months after flowering, which is necessary for next year’s blooms. The bulb foliage is also an issue in lawns.
I prefer stress-tolerators in turf that sync up with the mowing season like Claytonia virginica (spring beauty). This charming little plant blooms from December to March before going dormant. Later in the fall, Lycoris radiata (red spider lily), Rhodophiala bifida (oxblood lily), Habranthus tubispathus var. texensis (copper lily), and Zephyranthes chlorosolen (evening rain lily) bloom with their foliage emerging later and remaining up after frost. The last two have the added benefit of going to seed within a few weeks in case you need to do a few last cuts to the yard.
Zephyranthes chlorosolen (evening rain lily) blooms after a good rain. I’ll wait to mow over them until they set seed about three weeks later.
4. Disturbance for Managing Unwanted Plants
Disturbance is key to controlling unwanted plants and keeping competitors in check. In my garden, I use flame weeding and shallow cultivation to manage areas where weeds can take over. I’ve also invested in a Dutch hoe praised by Roy Diblik, which allows for easy push-pull weeding in tight planting spaces.
Tools like the wire weeder help me keep the soil disturbed to reduce weed growth.
5. Cutting Back Competitors
Many people have heard of the Chelsea Chop that helps to reduce upright growth. It is a form of disturbance that keeps competitive plants in check. It reduces their height, delays flowering, and makes blooms smaller but increases their number. While it is typically done in late May further north, I may cut plants back once or twice throughout the growing season.
I cut back a number of species here at Ephemera Farm to prevent them from flopping over—Eutrochium fistulosum (hollow joe pye weed), Vernonia baldwinii (western ironweed), Symphyotrichum (asters), Panicum virgatum (), Helianthus angustifolius (), and other giants. Most cut backs happen
Many of our the aster species I use from more northern haunts also have the issue that they emerge early enough in the spring that flowering is triggered under the short days. Cutting them back resets their flowering.
Cutting back competitors also helps reduce the ‘naked knees’ effect, where the lower foliage withers away and leaves bare stems.. A late spring or early summer cut back helps make clumps look tidier throughout the whole plant.
Symphyotrichum drummondii (Drummond’s aster) stems are already elongating in early April, and left unchecked will result in wiry stems come September.
Cutting Symphyotrichum drummondii to the ground helps reset the plant growth and results in a more densely flowering perennial.
The off white flowers of Symphyotrichum drummondii appear in a mound from a plant cut back the previous spring.
By applying Grime’s Triangle to my plantings, I create dynamic, resilient garden spaces that evolve with the seasons and thrive in various conditions. Understanding plant strategies helps me place the right plants in the right spots, which ultimately leads to healthier, more sustainable plantings.
Now, it’s your turn. Whether you’re filling gaps in your garden with fast-growing ruderals, using competitors to outcompete weeds, or diversifying your plantings with stress-tolerators, the principles behind Grime’s Triangle can guide you to make smarter planting choices. By observing your plants’ behaviors and using their strategies to your advantage, you can create a garden that not only looks beautiful but thrives with less maintenance and more resilience. Start small, test a few strategies, and watch how your garden transforms with the power of plant strategies in action.
Want to learn more? My presentation The Plant Strategies Playbook (⬆️) delves further into Grime's Triangle—an approach combining site, species, and management into one powerful framework. If you're eager to make smarter planting choices, fill gaps in your garden, and predict how plants will grow, this session is for you. Save time, resources, and become the eco-friendly gardener you aspire to be!