Roots of Native Plants

The prairie is a unique ecosystem with great diversity of plants. This diversity is extremely important because there are so many niches within the prairie. These are created by differing rainfall averages across the expanse of the landscape from west to east, different soil types and different depths of soil for plants to grow. This adaptability and resiliency of plants is correlated in part to the root systems associated with many native plants.

Photo used by permission from Nature Education-1995 Conservation Research Institute, Heidi Natura.

Plants grow in community

For so long, we have thought that the deep roots of many of these native plants translated to their ability to withstand drought and extreme temperatures. However, more research is pointing to the fact that most of the water absorption occurs in the top two to four feet of the soil profile. As it turns out, plants grow in community with each other and each above ground layer (groundcover, seasonal theme, and structure) draws moisture from different zones within those few feet of soil. This allows them to grow harmoniously together and not in competition with each other. This is the matrix planting concept, which mimics what happens naturally within a prairie. 

Narrowleaf Coneflower in the Flint Hills

Why are deep root systems important?

What we see above ground is typically only a third of the overall plant.  Roots exist out of sight and can reach anywhere from 8 to 14 feet into the soil.  Yes, these extensive roots do absorb moisture and nutrients but they do so much more.  They play an important role in helping a plant grow, thrive and improve the environment around them.

These hidden roots also:

  • Anchor the plant in the soil as plants try to reach for sunlight
  • Store excess food for future needs underground
  • Nourish the soil by dying and regrowing new roots each year, which builds top soil 
  • Fix nitrogen in the soil (legumes)
  • Increase bio productivity, by absorbing and holding toxins and heavy metals, carbon sequestration
  • Prevent erosion – fibrous roots hold the soil and absorb more runoff (as in a rain garden)
Butterfly Milkweed

I believe that native plant roots make these prairie plants resilient in the landscape. They are adapted to our local soils, rainfall and nutrients. In the 2011 and 2012 drought years, we observed native plants blooming in the fall, even after enduring 50+ days of 100 degree temperatures. This could not have happened without a healthy, sustaining root system. 

So while we learn more about the root systems of native plants and the sustaining role they play within the life of a prairie, we know that bringing native plants back into our environments continues to have so many positive benefits. Let’s work at getting more native plants into our landscapes and let them flourish.

Saturated Soils and Wilting Plants

This year we have been facing many environmental challenges from wind, drought, torrential rain for a lucky few, and now soaring temperatures. Nobody said gardening in Kansas would be easy. One of the more common problems we see in spring is wilting plants, especially those that are newly transplanted. This is true after the big rains last week and now the heat of this week. The new gardener may wonder – “what’s wrong with my plants?”

Saturated Soils

The heavy rain has resulted in saturated soil. Plants need water, but standing water for hours or even days depletes the soil of valuable oxygen. The roots need oxygen present in the soil, but as voids are filled with water, the oxygen is removed and root systems can become damaged. The fine root hairs die from lack of oxygen. These fine hair roots are vital for water and nutrient uptake by the plant. Whether it is a perennial or vegetable crop like tomatoes, the plants wilt because the uptake of water has been interrupted.

Will the wilting plants recover?

A number of factors affect the plant’s ability to overcome a flooding episode. How long the plants were flooded, drainage away from the root system, type of soil, type of plants (think about their natural habitat: some plants appreciate wet soils while other don’t), and how long the plant has been established. A newly established plant will be more affected than a mature plant.

Liatris wilting

Many vegetables crops are sensitive to flooding or saturated soils, but if the soil dries out quickly they will usually recover on their own with no help from us. Heavily mulched plants with more than two to three inches of mulch tend to stay wet too long for many perennials. If you see this wilting happening, check soil moisture. The mulch is not allowing the soil to dry out and may be damaging the roots. Rake back the mulch for a few days to encourage the soil to dry out.

If the soil stinks, then it has transitioned into an anaerobic state and everything is killed in the soil, including microbes and roots. Not a good situation. At this point it is very difficult to bring a plant back, because it is too badly damaged. Native plants generally appreciate good drainage. Root rot or crown rot are two of the most common problems, because the soil stays wet too long. As an example, narrow-leaf coneflower (Echinacea angustifolia) grows on rocky hillsides with keen drainage and no standing water. Planting one of these coneflowers in a flat garden with heavy clay soils is a recipe for disaster.

This time of year, gardeners should also be on the lookout for increased incidences of diseases such as early blight and powdery mildew. Humidity and excess moisture can quickly damage plants with these diseases, too.

Yellow Leaves

Echinacea turning yellow from too much water

Yellowing foliage can also be a problem after a heavy rain event. This is a visual indicator of compromised roots, but also the leaching out of nitrogen in the soil. Nitrogen is mobile in the soil and moves downward away from roots with moisture. An application of slow-release fertilizer like Osmocote or a liquid fertilizer will green the plant back up over time.

I only recommend fertilizing fully established perennials, i.e. plants you put into the ground last year. Fertilizing newly planted perennials will cause excess top growth without a sustaining root system. With native wildflowers and grasses, it generally takes three to five years to develop a sustaining root system.

To avoid these problems, it is critical to match plants to your site. Good drainage and keeping moisture away from the crowns of the plants will keep your plants healthy too. Don’t put too much mulch around your plants, especially the main stem. Plant your garden densely and let the plants be the mulch.

If you do mulch your garden, only put enough to just cover the soil. Usually one to two inches is enough. Allow the plants to develop roots that tap into the moisture and nutrients. We need the spring rains, but sometimes we can get too much for our newer perennials.

Spring Ephemerals: Don’t wait!

Because of the tendency for some spring ephemerals to go dormant in hot weather, there are a handful of plants we only offer at the spring Florakansas event. Shooting star, liverleaf, and jack-in-the-pulpit are all beautiful woodland species and that show off in spring then disappear for the rest of the year. If you wait until fall to buy these beauties, you likely won’t find them on our greenhouse benches! Though Florakansas is over, we still have some of these plants in stock, and I will be happy to chat with you via email if you’d like to purchase them.

Hepatica americana

Hepatica blooms very early in spring, sometimes even through the snow.
Photo via Wikimedia Commons

Also known as liverleaf, this petite plant puts on small star shaped flowers and is very hardy. Great in moist to medium-dry shade, it will perform in the garden without any fuss. The flowers can be white, or even a light blue or pink at times. Blooms close up at night and open on rainy days, a charming movement in the early spring garden. The leaves hug the ground at only 2-3″ tall, so it fits well near edging or walkways.

Dodecatheon media

Shooting star comes in pink and white. Whichever color you choose, they are sure to delight as they spring up in April on leafless stems. With a flower unlike any other, this native oddity is a conversation starter and always a welcome harbinger of warmer days to come. Plant in a part shady spot where the soil won’t become waterlogged, as they may rot. Once finished blooming in May, the plant disappears completely only to surprise you again next spring!

Arisaema triphyllum

Photo by Fanmartin via Wikimedia Commons
Native range of A. triyphyllum according to the USDA plants database

Jack-in-the-pulpit is a fascinating plant that looks more like it belongs in the tropics than in Kansas. Native to eastern Kansas and much of the mid to upper east coast, this plant spreads slowly underground to form lush colonies of lobed leaves and spathe blooms. The blooms are green externally, but often turn burgundy red inside, eventually giving way to interesting red fruits in fall. But take care, though they may look delicious, these fruits are not edible!

Other spring ephemerals that go dormant during summer and are only offered in spring are Mertensia virginica (bluebells) and Podophyllum peltatum (mayapple). Though Florakansas has ended and the shopping hours are over, if you still need a few plants please email arboretum@hesston.edu to reach a staff member and we will be happy to help.