Growing Native Wildflowers on the Colorado Front Range

When people grow native plants, the plants are domesticated or becoming domesticated, whether we intend it or not. The conditions in yards and gardens are pretty different from growing in the wild, even in the same location. This post is about that contrast.

black-eyed Susans, Rudbeckia hirta, in a garden

Native plant enthusiasts only want to grow straight species, unmodified by cultivation or breeders. But they want to grow them in their yards. In some places (Virginia?) rich loamy soil may be what the natives grow in. However, here on the Rocky Mountain Front Range, the native soils are shallow, only a few inches deep in many places, with little organic matter. They are alkaline or at best, neutral in pH. The soil maybe be very sandy, or full of small rocks.

Below, soil in the City of Boulder Open Space: lots of rocks and bare ground. The photo was taken in a dry July. 

The photo focuses on the plant in the center,winged wild buckwheat, Eriogonum alatum (buckwheat family, Polygonaceae). The plant stands about 3' tall but is so open that the camera and the eye look right through it. See the yellow flower buds on the smaller reddish rock and follow the branches back to the stem.

Front Range soil

Here is the soil of a sandy area in eastern Colorado. That is fine sand with lots of bare ground. 

Photo taken for Texas croton (Croton texensis, spurge famly, Euphorbiaceae), the white-ish plant in center. They are dioecious, this is a male (staminate) plant). 

sandy soil, eastern Colorado

We are taught to amend soils like the ones above, adding organic matter (fertilizer or compost), watering frequently. The amount of water a Kentucky bluegrass (Poa praetensis, grass family, Poaceae) lawn needs to stay green is about twice the annual rainfall of the Front Range, so a yard growing bluegrass represents a very wet year to the natives. 

Native plant enthusiasts get straight species wildflowers, plant into good garden soil and water three times a week. These are alien conditions. The plant may grow bigger and taller, but it may also be exposed to pathogenic bacteria and fungi encouraged by the nutrients or root rot from all that water. 

Two examples of natives that find gardens alien:

bush morning glory,  Ipomoea leptophylla, in eastern Colorado

People would like to grow the bush morning glory, Ipomoea leptophylla (morning glory family Convolvulaceae). Native from Montana to Texas, it has big pink tubular morning glory flowers and forms attractive clumps. It grows in sandy soils. Below ground, it produces a root-tuber several feet under the soil surface. Probably water in the tuber is at least part of why the morning glory above is green while the surrounding plants are brown. (In the photo, green to the left and up is part of the morning glory, a clump of green in the center of the photo is a grass, and I can't identify the green leaves in the upper right quarter.) The soil needs to be very well-drained or the morning glory's tuber rots. Compared to the grasslands of eastern Colorado, gardens are soggy. Bush morning glory roots are not very compatible with typical gardens. 

bush morning glory, Ipomoea leptophylla
showing root tuber (yard/meter stick for scale)

buffalo grass, Bouteloua dactyloides, lawn 

People are also growing buffalo grass (Bouteloua dactyloides, formerly Buchlöe dactyloides, grass family, Poaceae). Historically this was a dominant grass across much of the high plains. In nature, buffalo grass is a mean competitor. It makes a thick tangle of roots in the top few inches of the soil. The roots form a sod dense enough that it was the preferred grass for cutting into chunks to make the walls of sod houses: buffalo grass sod held together the best. That tangle of roots meant that in a light rain, buffalo grass intercepted all the water and let none of it get to lower layers of the soil. Plants with deep roots or tap roots growing amid buffalo grass died of thirst. Under drought conditions, buffalo grass goes dormant, pale brown, but is waiting, not dead; with water, it will green up within a few hours. Buffalo grass can kill dandelions and other ubiquitous lawn weeds if it is kept very dry. With normal watering, as for bluegrass, buffalo grass loses its edge. 

Microhabitats matter. “Native plant” is generally defined geographically: does it grow in this county? But counties are complex, with sandy soils and clay soils, upland areas, areas that flood, and stream banks, at minimum. We buy “native plants” without a lot of information about where specifically they grew. I studied native prairie plants in unplowed grasslands, so I had to find them. I got good the microhabitat native plants liked. The bush morning glory was most abundant on sandy slopes, not flats or in valleys, and along fence lines. Buffalo grass grew abundantly on level non-sandy areas. The garden may not have those conditions or I may not know enough to put purchased natives into the right microhabitat.

wild bergamot, Monarda fistulosa, in a mountain meadow

Eastern prairies (tallgrass prairies, Illinois to eastern Kansas) were moister than the western plains; the plants grew taller, to 6' or more in a wet year. A lot of their wildflowers are offered as native wildflowers across the continental U.S. For example. coneflowers (Rudbeckia, sunflower family, Asteraceae), swamp milkweed (Asclepias incarnata, dogbane family Apocynaceae) and wild bergamot (Monarda fistulosa mint family, Lamiaceae) are tallgrass prairie wildflowers. These are indeed native along Colorado’s Front Range, along streams or other places with extra water. These tallgrass prairie plants expect twice the rainfall of the Front Range of Colorado and so in most places do not do well without supplemental watering. What works for them is probably too much water for short grass/high plains species like fringed sage (Artemisia frigida, sunflower family Asteraceae), sulfur flower (Eriogonum umbellatum, buckwheat family, Polygonaceae), and rabbitbrush (Chrysothamnus nauseosus, sunflower family, Asteraceae). Habitats varied and much of the Front Range is very dry. 

fringed sage, Artemisia frigida, less than 6" tall

Wanting to grow plants that are not adapted to gardens is a recent change. Historically, people with gardens went to a store selling garden plants and bought plants for their yards. Those plants love garden conditions. Many have been grown in gardens for 2,000 years, rosemary, peonies, and roses, for example. They are well-adapted to enriched soils and regular water. We did not think much about how our gardens differ from the wild plant communities we replaced. Now, we are trying to grow the plants of shortgrass prairies or desert grasslands in our yards and should stop and reflect on how the garden environment is different.

garden roses

There are two pathways forward: bring the conditions of the garden to be more like those of the natural areas, or select for wildflower varieties that thrive in the garden environment. Probably both will happen, but becoming conscious of the contrast improves the decisions a gardener makes, regardless. 

purple cone flower, Echinacea, in a garden

I struggle to really see the environment I provide in my garden and not assume the natives I bought will like growing just anywhere in it. 

More on plants adapting to being grown by humans in future posts. 

Comments and corrections welcome

References

Ackerfield, J. 2022. Flora of Colorado. 2nd edition. BRIT Press. Fort Worth, Texas. 

Weaver, J. E. 1968. Prairie Plants and Their Environment. University of Nebraska Press, Lincoln, Nebraska.

More on bush morning glory in this blog link

More on buffalo grass in this blog  the amazing drought-tolerant buffalo grass  link(dioecy)

Kathy Keeler, A Wandering Botanist
More at awanderingbotanist.com
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Please take a look at my books. For those who don't read the internet or prefer books I gathered posts together into actual books, for example:

NoCo Notables, Stories of Common Plants of the Colorado Front Range, Plants have cool stories, about their interactions with other plants and animals and with humans. Go beyond just having a name for the plant, learn more about it. Available from Amazon link or from me. 

 

                                            

And

Look Twice, containing stories of plants from the unique environments found in western Nebraska and eastern Colorado, available from Amazon  link or from me. 

New book coming this summer: Plants You Meet Everywhere. The stories of really cosmopolitan plants such as marigolds, bougainvillea and cheatgrass.