Reasons to Leave Ornamental Grasses In Winter

Posted on September 29, 2021 by Scott Vogt

The use of ornamental grasses in the landscape has become more popular than ever, and for good reason. The allure of ornamental grasses is that they are tough and easy to grow. Their resilient nature reflects our prairie landscape in our own garden. They are a nice visual contrast to many other plants like perennials, shrubs, trees and even other grasses. A bonus is the beauty and movement they add to the winter landscape.

*Liatris and Indian grass in the Prairie Window Project, Photo by Brad Guhr*

One of the questions we get this time of year is whether or not to cut ornamental grasses back to the ground for winter?

In the fall, ornamental grasses are in their full regalia with their attractive seed heads. From short to tall, these grasses put on quite a late season show. As we transition into fall, the colors they develop are another reason we use them in our landscapes. However, these fall colors fade and we are left with dull shades of tan and brown. Is it best to leave these grasses now or remove them? Generally, we leave them through the winter, and cut them back before they begin to grow next season. In Kansas, this task can be done in late February to early April.

Here are some of the advantages of leaving grasses for the winter and waiting until the spring to cut them back

Grasses provide form and texture in the stark winter landscape of withered perennials and deciduous shrubs. These qualities stand out in the frost or snow and low winter sunlight.
Mix well with perennial wildflower seed heads
Provide movement in the garden. The tawny stems and seed heads move with the gentlest breeze.
If used as a screen, they can be left up just before they start greening up again in the spring.
Most native grasses can provide habitat and shelter for birds and other small animals along with overwintering sites for insects and pollinators.
By waiting to remove the previous year’s growth until late winter, the crown of the grass is more protected from the elements.

*Little Bluestem and Coneflower Photo by Emily Weaver*

How do I cut back my grasses?

After leaving the stalks up through the winter, they are drier, more brittle, and easier to cut back. I like to cut tall grasses like switchgrass and big bluestem down to about 2-3 inches off the ground. I do this with a hedgetrimmer by moving it back and forth across the stalks a few inches at a time. We used to completely remove these stalks and haul them away. Now, we let the clippings lay as mulch around the plants. These stalks may still have overwintering pollinators in the stalks that are left in the garden for next season. By spreading the cut stems around as mulch it helps to break down more quickly too. I shape smaller grasses like prairie dropseed with a pruner or hedgetrimmer. Again, I like to cut them back to two to three inches from the ground.

Over the years, we have found it very beneficial to leave ornamental grasses standing for the winter. You’ll be creating a habitat for birds, insects, and small animals. The rustling grasses will remind you of the successful season past and the promise of spring yet to come.

*Switchgrass cut back in late winter ready for spring*

Landscaping with Plant Communities in Mind

Posted on September 17, 2021 by arboretum-admin

This blog post is updated and republished. Previously published as “The Social Network for Plants” in September 2017.

One of the landscaping concepts I touched upon in my recent Matrix Planting class is the idea that plants are members of a complex social network. No, they are not on Facebook, Instagram or tweeting about the conditions on their side of the prairie, but they do grow best in a company of friends. I enjoy the idea that even though each plant is unique, they are part of interrelated communities. They complement each other and live in harmony, which makes them so much more resilient together than if they grow isolated and alone.

Plant communities in the wild

Nature is a great teacher. Look at wild plant communities. Whether a forest or a prairie, you will find plants growing harmoniously together. There aren’t any mulched areas between plants, but rather intertwining, interlocking and dense groups of plants growing side by side. A compass plant reaches up through tall grasses like big bluestem and indiangrass. The deep tap root punches through the fibrous roots of the grasses, and the tall grasses help prop up the compass plant’s long stems and keep them from flopping over. If you plant compass plant in your landscape, plant it with these tall grasses. Plants grow in environments that suit their growth habit.

Butterfly weed is another great example. In the wild, it would get smothered and lost in five to six foot grasses, but you see it flourishing with shorter grasses like little bluestem, prairie dropseed and blue gramma. Grasses of similar height is what they prefer. The beautiful orange blooms are at the same height as the grasses. These plants also have similar sun, soil and moisture requirements, too.

Know more about the plants you grow

An understanding of plant communities and the preferences of individual plants will help direct your landscape design. This approach to landscaping forces you to become familiar with each plant, but rewards you with a successful landscape that mimics the communities on the prairie. By adapting your gardens to include groups of plants that naturally occur together and that match your own landscape, you will have a functional, low maintenance landscape that is ecologically responsible and beautiful at the same time.

*Urban prairie photo courtesy Craig Freeman*

This style of landscaping has caused me to reevaluate how I design new plantings. For instance, switchgrass, which is one of my favorite grasses, is a solitary grass in the wild. It forms large colonies with other wildflowers growing on the edges of these colonies. Richard Hansen and Friedrich Stahl, in their book “Perennials and their Garden Habitat”, arrange plants according to their sociability level. Plants like switchgrass or coneflowers at lower levels (1 and 2) are set individually or in small clusters. Plants like prairie dropseed or blue grama at higher levels (3 to 5) are set in groups of 10 to 20-plus, arranged loosely around the others.

By observing the different levels of plant sociability, it guides how you incorporate plants into your landscape. It is an ecological way to garden that focuses less on aesthetics and more on relationships of plants. Of course height, bloom time, texture and flower color are important, but they are not the most important consideration when planting. The main emphasis now is grouping plants together that thrive in the wild together.

So what does this look like practically in your landscape?

It looks like 10-20 coneflowers (level 2 plants) propped up with little bluestem, prairie dropseed and blue grama (level 4 plants). In the wild, you never see just coneflowers growing in large solitary groups together, but mixed with other wildflowers and grasses. Blue sage (level 2 plant) has a tendency to flop, but when combined with other taller grasses and wildflowers, its blue flowers are held at eye level. The taller, more upright plants or solitary plants in levels 1 and 2 need the level 3 to 5 plants to grow and spread around them. This interlocking matrix of plants covers every square foot of your garden. Weeds are crowded out and maintenance is reduced over time as these plants squeeze out unwanted species. You can now manage your plant communities as a whole rather than taking care of each individual plant.

*Native prairie photo courtesy of Craig Freeman*

I believe this approach to designing a landscape has many benefits. Using this approach, we will become intimately acquainted with the plants we grow and the social communities in which they thrive. This connection to our plants forces us to learn about them. More importantly we begin to see them as individual pieces of a much larger collection of associated plants. It is a radical shift in how we design a garden. Plants are pieces that nature weaves together in ecological combinations. Nature is a great teacher.

Insects – Motivation for Native Landscaping

Posted on September 9, 2021 by Brad Guhr

Early September blooming plants are attracting loads of nectar-sipping insects right now. Host plants are green and thriving from timely rains and providing food for munching larvae. All this insect activity has led to great enjoyment for me in exploring the Dyck Arboretum grounds and my home landscape. It has prompted me to think more about my real motivation for landscaping with native plants.

*Gulf fritillary nectaring on prairie dock*

Plants or Insects?

For many years, I’ve claimed that my enjoyment of native landscaping was motivated by my love of plants. Indeed, their flowers, seed pods, seeds, seed dispersal mechanisms, and roots are all interesting traits and worthy of appeal. Getting to know their growth habits, moisture and light preferences all translate to the level of success I will have (or not) in establishing these plants in a given landscape. And early in their establishment, my focus is geared toward making sure they stay alive with my watering, mulching, and weeding efforts.

*Common milkweed wind-blown seed dispersal mechanisms are cool to observe. But I am increasingly interested by the insects this plant attracts too (like the milkweed bug)*

But as these long-lived perennials develop substantial root systems, become established, and begin to flower, I worry less about their survival. My perspective changes, turns towards what they can do for the local ecosystem. New questions arise. What insects are attracted to their flower nectar? Which insects are pollinating them and leading to seed production? What insect larvae are eating their leaves or other parts of the plant? What predators are in turn feeding on those insects?

*Simple image of a prairie food pyramid (**Credit:** Mariana Ruiz Villarreal (LadyofHats) for CK-12 Foundation)*

Plants, being at the base of the food pyramid, dictate the level of diversity that exists further up the pyramid of consumption. Small bases lead to small pyramids and bigger bases lead to bigger pyramids. So in theory, the more different species of plants I install in my landscape, the more species of insects I will host. I can specifically predict what insects I will attract to a landscape based on the larval host plants I establish. For example, milkweed species will draw in monarch butterflies. Golden alexander or other species in the parsley family will draw in black swallowtail butterflies. Willow species will draw in viceroy butterflies, and so on. HERE is a list of butterfly larval host plants.

The Insects Have It

When I stop and think about it, the most interesting parts of tours at the Arboretum are when insects are visible and busy doing their thing. Stopping with a group to watch a hatch of caterpillars devour a plant leaf and dream of what those caterpillars will turn into is pretty cool. Observing a huddle of school kids dump out a sweep net and squeal with delight at finding the baby praying mantis, massive grasshopper, or whatever other interesting insect they are not used to seeing, simply makes my day.

*Milkweed tussock moth larvae feeding on common milkweed*

*Tour participants observing monarch caterpillars and milkweed longhorn beetles on common milkweed*

*3rd Graders investigating the contents of an insect sweep net*

Many of the species blooming now around the Visitor Center at Dyck Arboretum are sometimes considered invasive and perhaps even uninteresting because they are common. But as I highlight in another blog post Finding Value in the Undesirables, they attract a load of insects which makes them interesting to me. Here is a collection of photos of insects taken just outside my office last week:

One particular plant, Leavenworth eryngo (Eryngium leavenworthii), is stunning due to its vibrant color and interestingly shaped features. It’s often noticed by visitors walking to the greenhouse during FloraKansas: Fall Native Plant Days. However, what most people say when they see it is “did you see the swarms of insects on that plant?!” Customers are eager to recreate such insect habitat at their homes. For this reason, I keep a bag of seed for this annual species collected from the previous year to give away.

Become An Insect Promoter

This subtitle may make many traditional gardeners cringe. I have recently followed social media groups of gardeners where the anti-insect sentiment is rabid. Pesticides are commonly recommended to get rid of insect hatches in home landscapes and the recoil response related to spiders in general can be disturbing. Even many of our dedicated members that love to buy native plants for their landscapes don’t like to see the plants they come to love devoured by caterpillars. I am on a mission to change that.

So, if you are not already an entomology enthusiast and in awe of insects, I encourage you to take on a popular motivation for landscaping with native plants. Become more open to welcoming insects. Choose native plants or native cultivars not only because you think they will be pretty, but for how they will eventually host insects, enhance the food web they support, and increase the wildlife diversity in your landscape.

Plant Profile: Black-eyed Susan

Posted on September 1, 2021 by Scott Vogt

Black-eyed Susan (Rudbeckia sp.) are one of the most recognizable summer-blooming wildflowers. Their bright yellow flowers explode in the summer and are covered with all sorts of pollinator activity. Bees, flies, butterflies, and beetles feed on its nectar and pollen. The fruiting heads also provide seed for birds over the winter. Here is a look at a few species and cultivars worth trying.

Missouri black-eyed susan (Rudbeckia missouriensis)

In the wild, Missouri Black-eyed Susan grows in rocky limestone glades, barrens, and tallgrass prairies. It ranges from Illinois and Missouri, south to Arkansas, Oklahoma, and Texas. Although not native to Kansas, I have found it very resilient and quite adaptable to various growing conditions. It has large bouquets of bright yellow flowers atop 18” stems. The foliage is narrow with the leaves and stems covered with a dense fuzz. It’s a nice addition to the front/middle of any border or informal meadow landscape.

Brown-eyed Susan (Rudbeckia triloba)

This native gem can be found in eastern Kansas and on into much of the southeastern Great Plains. It grows naturally in open woods and savanna areas with medium to moist soil. Each plant can produce loads of charming, warm yellow daisy flowers with brown button centers. It keeps pumping out blooms through much of the later summer through fall. The slender branched stems are surprisingly sturdy and help the plant reach an ultimate height of three to four feet. It is a wonderful habit plant with blooms for pollinators and seeds for birds. It does self-sow, so know that it will move around. You will need to selectively weed plants out of your landscape, if you are agreeable to that sort of thing.

We have carried a cultivar of Brown-eyed Susan called ‘Prairie Glow’ with attractive flowers of burnt orange with yellow tips surrounding a chocolate center cone. ‘Prairie Glow’ prefers full sun to light shade, and is also adaptable to many soil conditions.

Sweet Black-Eyed Susan (Rudbeckia subtomentosa)

Sweet black-eyed Susan grows throughout much of the central and eastern Great Plains in low, moist soil of thickets, creek banks, pastures, prairie ravines and ditches. The flowers are spectacular and rival sunflowers in quantity of blooms, if the root system can find consistent moisture. A large variety of insects love the nectar and/or pollen of Sweet Black-eyed Susan and flock to the blooms during July, August and September.

This is a great plant for a full sun to part shade location, but only when there is ample moisture. It will not endure dry soils. Plant it by a stream, water garden or pond where water is available on or near the surface. ‘Henry Eilers’ is a nice cultivar discovered in Illinois as a stabilized mutation with rolled or quilled ray petals. This cultivar reaches five feet tall and two feet wide. ‘Little Henry‘ is a shorter form which grows 3 to 4 feet tall but has the same quilled flowers.

Photo courtesy of TERRA NOVA® Nurseries, Inc.
www.terranovanurseries.com

Black-Eyed Susan (Rudbeckia hirta)

There are many forms of this poor man’s daisy, because it is so easy to hybridize. Typically, the species is found in full sun to part shade in mixed and tall grass prairies as a short-lived perennial or annual. It seeds readily and is a favorite to include in many prairie seed mixes. The bright yellow blooms from June through September are a welcome sight in any landscape from prairie to wildflower seeding. Some cultivars available are ‘Cherry Brandy, ‘Prairie Sun’, ‘Cherokee Sunset’, ‘Indian Summer’, ‘Autumn Colors’, ‘Denver Daisy’, ‘Goldilocks’, ‘Goldrush’, ‘Rustic Colors’, ‘Sonora’, ‘Toto Gold’, and ‘Toto Lemon’.

Cutleaf Coneflower (Rudbeckia laciniata)

This species grows in similar habitats to sweet coneflower – moist soil of creekbanks, thickets and open woods. A cut leaf coneflower really stands out in full sun and adequate moisture. The leaves are deeply lobed and the large, wide clumps, two to four feet across, can reach five to six feet tall. Each stalk can have multiple large flowers with a greenish-yellow central cone. They bloom from July to October. A garden worthy cultivar of cut leaf coneflower is ‘Herbstonne’.

Orange Coneflower (Rudbeckia fulgida)

This eastern United States black-eyed susan is one of the most widely used in horticulture. Many cultivars, varieties and subspecies are incorporated into landscape designs. The native form thrives in glades, meadows, and prairies. Rudbeckia fulgida var. deamii, Rudbeckia fulgida var. fulgida and Rudbeckia fulgida var. speciosa are two of my favorite native forms of orange coneflower. They grow well in landscapes with medium to moist soil and plenty of sun. These clumps slowly spread by rhizomes ultimately forming a dense mat of dark green leaves. The blooms pop up from July through September.

‘Goldsturm‘ was a popular cultivar, but it has been used less because it has issues with septoria leaf spot and powdery mildew. New forms like ‘American Gold Rush’, ‘Little Goldstar, and ‘Viette’s Little Suzy‘ have resistance to both septoria leaf spot and powdery mildew. These are great alternatives to ‘Goldsturm’.

Giant Coneflower (Rudbeckia maxima)

*Prairie Dropseed (foreground), Rudbeckia maxima, and yellow coneflowers*

I love this coneflower for its blue green leaves and large coned flowers in June and July. It makes quite a statement in the landscape with flower stalks to six feet. Native to Texas, Oklahoma and Louisiana, I have found it to be quite adaptable. It appreciates regular moisture but can handle some dry periods. Birds eat the seeds from the large cones during the winter.

There is a Rudbeckia for just about any landscape situation with full to part sun and wet to dry. Pollinators love them and birds too. Add some to your garden for their late season bloom.