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Lavender, Butterfly Weed, and Little Bluestem - What's Not to Love?

I previously designed a plant community with 'Phenomenal' Lavender (Lavandula x intermedia 'Phenomenal') and later native Little Bluestem (Schizachyrium scoparium) into a mix outside my kitchen. This spring, I'm adding the beautiful orange blooming Butterfly weed (Asclepias tuberosa), another native species, and I can't wait to see how they all grow together.

But Lavender is Not Native?

There is nothing native about Lavender to North America, whose origins are the dry heat of the western Mediterranean. Phenomenal Lavender is a French hybrid. I'm using this perennial herb in my mix because, in addition to using native plants, I love plants that are non-invasive (don't spread uncontrollably), play well with others, and share the same soil and climate needs of native species. That means in addition to increasing my use of natives, cultivars (nativars) hybrids and exotics can all be part of the planting mix - provided they meet specific criteria.

In their book: "Planting In A Post Wild World," Thomas Rainer and Claudia West state there are two conditions that must be met for a "designed planting to become a community." The first is that "all plants chosen should be able to survive in similar environmental conditions," and secondly, "the plants must be compatible in terms of their competitive strategies." They go on to say, "Designed plant communities place the emphasis on a plant's ecological performance, not its country of origin." I will address the current research on cultivars vs. natives and their differing impacts on wildlife in an upcoming post.

Incorporating Non-Native Plants into Your Native Garden

So I've met the first condition. Lavender has the same environmental conditions in common with Little Bluestem and Butterfly weed - all three don't mind sandy, dry, relatively infertile soil and intense sun, which are precisely the conditions outside this part of my house.

The second condition deals with the "competitive strategies" of plants. We'll keep the definition simple. When you mix plants, whether they be all natives, cultivars, non-invasive exotics, etc. you'll want to know what strategies they use to survive and reproduce - in other words, you'll want to ask:

  • What is their approach to competing and staying alive?

  • Will some plants grow taller than the others and block out the sun, eliminating the others around them?

  • Do they reproduce aggressively by rhizomes that grow horizontally in the soil shooting new stems out of their nodes?

  • Or do they mostly stay in place growing in a large clump?

You also want to know as much as you can about their root system. Plants do a fantastic job of finding their layer of soil in which to extract nutrients and moisture. Plants living successfully together, and what appears to be almost on top of each other, is because they occupy a different level of the soil underneath them - therefor not directly competing with their neighbor, at least underground. And some plants live symbiotically, surviving by intertwining their root systems with other plants.

Lavender is shallow-rooted, approximately 8-10 inches in depth. Butterfly weed has a taproot up to 3 ft, and Little Bluestem grows a taproot up to 5 ft. Long taproots are one reason people have such a difficult time digging these natives up on the side of the road - they leave most of the root system in the ground - but these extensive roots help native grasses and flowers withstand periods of drought.

Since the Lavender roots will be near the top of the soil, and Butterfly weed and Little Bluestem will occupy different deeper layers, I'm confident they should all work together and manage to find their place for nutrients and moisture - at least underground.

One benefit of using more natives in the garden is you can already observe how they act in nature. Most of us have seen fields of Little Bluestem punctuated by Butterfly weed - so I know they can grow well together and likely keep each other in check.

How the plants grow on top of the soil is of obvious importance as well. Phenomenal Lavender grows bushy, 2-3’ in height and 3-4’ wide in optimal conditions, and will undoubtedly smother any sun-loving shorter plants underneath it - and weeds. Its seeds don't germinate readily on their own, so I'm not worried about it overtaking the garden.

Butterfly weed (a species of milkweed) also grows in clumps about 2 1/2' tall and half as wide, and spreads by seed but is not as aggressive as Common milkweed (Asclepias syriaca). I'm ok if it jumps from my test garden into other parts of the property, I just need to make sure I don't plant it too close to the enormous clumps of Lavender.

Little Bluestem grows 2-4' high and half as wide and is more of a squatty column than a clump, it is an aggressive seeder, but for my test garden on the edge of my meadow, I'm looking forward to it spreading around, in fact, I'm counting on it. Little Bluestem is known to fall over and get floppy, so I want to see if the high spikes of Phenomenal Lavender and sturdy stems and seed pods of Butterfly weed will hold it up. For clients that love the look of Little Bluestem but don't want it spreading all over the place and getting floppy, I would substitute with different cultivars with seeds somewhat sterile and possessing more upright growing habits. One fabulous variety I have used in the past is 'Smoke Signal' Little Bluestem (Schizachyrium scoparium).

Low Maintenance Gardening

Low maintenance gardening is essential in all of my designs. I don't have the time to pinch flowers and cut back stems throughout the garden. Don't get me wrong- it's a great way to spend time outside, and maybe I'll do it in retirement, but, for now, I need plants that look good with minimal guidance from me, which includes no fertilizing and no watering after plants are through their establishment period. So, for this reason, I did not cut my Lavender back. Lavender is a perennial herb, a subshrub. It will get somewhat woody and have a reduction in blooms because I don't cut it back after blooming, but that's ok with me. For my garden, I prefer flower colors a little more muted than most, and I think the added woodiness to the Lavender will help it naturalize better with the natives.

When I visited the Summerhouse Lavender Farm in the spring of 2019, Dan McGavin, one of the owners, told me they had suffered a considerable loss of any Phenomenal Lavender exposed to harsh arctic winds coming across the open field by their farm. In winter of 2020, Dan covered his Lavender plants for the first time to protect them. He says English Lavenders tend to be hardier then French varieties, so he has taken to planting more of them in his exposed areas.

Fortunately, my sunny garden spots where I planted the Lavender have woods around them, and I have very little wind in those locations, so fingers crossed my French Lavender will do fine. Needless to say, I'm full of confidence in the outcome of my test, but we'll see... that's the reason I like to experiment with plantings first!


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