Friday, January 31, 2014

Texture in the Prairie Garden: Bold

I gave a talk yesterday at the Spring Gardening Workshop here in Sedgwick County.  As always, I'm afraid, I had more that I wanted to share than I had time to talk in. (My Uncle Ed used to call me Windy Cindy when I was a child...probably with very good reason!)  I thought it might work well to share some of the ideas and suggestions I had for "(Re)Creating Naturally Functional Landscapes in our Yards and Gardens" on my blog. 

So let me start with one of the biggest problems I've run into as I continue to develop my own prairie gardens:  texture.   Many, if not most, of the prairie plants are medium in texture.  The leaves are medium in shade of green and medium in size.  The flowers are medium in size.  The plants tend to be 3-4 feet tall and about as wide.  It's very easy to get an overwhelming mass effect, but much harder to have a variety of different textures that create interest based on contrasting sizes, shapes, and forms.

First though, before I share some of my "secrets," I'd like to point out that the triumph of the "medium" in the prairie is, in great part, due to natural constraints.  Large leaves have large surfaces that tend to lose lots of water, which isn't good for plants growing in an environment famous for extended droughts and unceasing winds.  Speaking of those winds, they have a major tendency to rip large leaves and flowers to shreds which, ironically, leaves you with medium-textured pieces hanging on.

Color is another drought issue.  Generally, the wetter the climate, the deeper the green of the plants that grow there.  Hot, dry climates favor gray-greens.  The prairie, being half way in between those two extremes (and enjoying wild vacillations between the two), tends to stick in the middle with medium green shades.  In short, "medium" is so abundant in the prairie because it works very well there.

Medium, however, presents us with a problem of "too much of a good thing" when designing interesting gardens.  So here are some suggestions for prairie plants that break out of the "medium" mold, starting BOLDLY with plants that bravely present big leaves to the prairie winds.

Giant Coneflower:

Used increasingly in professionally designed landscapes, giant coneflower (Rudbeckia maxima) steers clear of medium in almost all aspects.  In the photo below, the giant coneflower is in the bottom lefthand corner, at the front of the flower bed....

Native to the southern Great Plains, it boasts large, gray-green leaves with a soft, waxy look that stay in a beautiful low rosette for much of the year.  During early-mid summer, giant coneflower sends up 4' tall spikes crowned with a single, large "boned" bloom:  a tall central cone, surrounded by drooping yellow petals.

If you can refrain from cutting off the finished blossoms to tidy up the garden, they provide a good seed source for winter birds while giving vertical accents to the winter landscape.  The hollow, dried stems are also great habitat for solitary bees, those native masters of efficient pollination.

Compass Plant:

A classic prairie plant and widely distributed throughout the center of the country, compass plant (Silphium laciniatum) is said to have helped pioneers navigate because its large, deeply lobed leaves tend to line up in a north-south orientation in order to capture the strongest rays of the sun.

When you touch the leaves of the compass plant, you understand how it compensates for the large leaf surface that it exposes to the prairie winds:  the leaves are very rough, thick and coarse to the touch, almost like a form of sandpaper.  Despite that unappealing feel, apparently cattle graze the leaves with great relish, so compass plant doesn't last long in pastures.

Although the leaves provide a basal rosette that is only 18"-24" tall, like the giant coneflower, the bloom spike pushes up 4-5' into the air.  Unlike the giant coneflower,  though, this spike is ornamented with 3" wide sunflower-like blooms along its entire length.  Compass plant blossoms start opening at the top of the spike and slowly work their way down the length of the stem over a period of several weeks.

Again, if you leave the spike intact when the blooming is complete, it provides visual interest as well as bird food and insect shelter throughout the winter.


There are several beautiful milkweeds that provide thick, large leaves and big balls of fragrant pink blossoms for bold texture in the garden.  The three that I'm most familiar with, and that occur naturally on our property, are somewhat hard for me to tell apart, but all three are very appealing plants.  All, too, are monarch larval plants and thus VERY important to plant for trying to save one of our favorite native butterflies.

Common milkweed (Asclepias syriaca) is probably the most well known of these three.  Its native distribution covers the central and eastern portions of North America.  Because of its tendency to spread by its roots, it has earned the reputation of a weed in cultivated fields and it probably wouldn't work in a formal garden, but it would be a great addition to an informal, cottage style border.

Here is a closeup of common milkweed's blooms, complete with monarch, for comparison with the next two plants.

The second milkweed, smooth milkweed (Asclepias sullivantii), is also known as prairie milkweed.  It is very similar to common milkweed, but its native distribution is much more restricted to the central prairies.  This is the one of these three "pink pomander" milkweeds that grows best for me, and it is the one that I have seen the most monarch caterpillars on.

Based on its native distribution, the third of these 3 pink milkweeds, showy milkweed (Asclepias speciosa), is almost a western version of common milkweed. 

Again, here is a closer look at the bloom.  Showy milkweed's blossoms have lo-o-ong, upright "petals", giving the bloom an almost spiky appearance.  They ARE certainly showy, though, which makes them the easiest of the 3 for me to identify!

All three of these pink milkweed species grow about 30"-36" tall.  I do not know how assertively either smooth or showy milkweed spread, compared to common milkweed.  None of the three form exclusive patches, however, in any situation where I have seen them growing; thus all three should be fine in an informal garden setting.

Before I leave milkweeds, let me briefly mention a common species that is perhaps worthy of consideration for incorporation into some garden beds:  green antelopehorn (Asclepias viridis).  Frequently seen in pastures during the spring, green antelopehorn blooms very early in the season and stays quite low, topping out at 18" but more commonly about 12" tall.  While the leaves of this milkweed aren't as big as those of common, showy or smooth milkweed, they are larger than almost any other plant growing at this time of year and thus they provide a bolder texture in the landscape, too.

Found primarily in the center of the country, this plant's creamy white flowers with eye-catching, inner purplish "clubs" are an intriguing contrast to more traditionally constructed blooms.

Oakleaf Hydrangea:

Although native just to the southeast of the U.S., I have seen oakleaf hydrangea (Hydrangea quercifolia) growing as far north as Ontario.  It grows well here, too, with a bit of protection from strong summer winds and from too much summer afternoon sun.

Oakleaf hydrangea is one of my favorite shrubs.  Its large, lobed leaves are attractive throughout the growing season, but they are especially vivid and eye-catching during the fall, when they turn a gorgeous burgundy, sometimes tinged with orange.  The bark is rather cinnamon colored and exfoliates as the shrub gets larger, while the dried flower heads remain throughout the winter, giving nice winter interest in the garden. 

Oakleaf hydrangea flowers, by the way, start out a beautiful, pale lime green, mature to white, get pinkish as they age, and end up a soft gray-brown, staying attached to the plant until the newly developing leaves and flowers push them off the following spring.  This is truly a 4 season plant!


If, from a distance, you see a tree whose large, light, bright green, heart-shaped leaves make it stand out from other trees, chances are you are looking at a catalpa.  In the picture below, the catalpa is the tree in the middle.  To its left is a bur oak, to its right is an osage orange.  The bur oak and the catalpa were planted about 20 years ago, I believe, but I don't know how old the osage orange is. 

Note how much more upright the catalpa grows, and how much lighter a green its leaves are.  One of the latest blooming trees, catalpa blooms in June, after its leaves are fully emerged.  The white blossoms are wonderfully fragrant and occur in big, showy clusters above the leaves.  If we move in closer here, we can see (and smell) the sweet flowers.

Somewhat oddly, those big showy clusters of flowers develop into long, thin pods that remain on the tree throughout the winter.  I find the tree with its winter dress of dangling, long pods to be quite attractive, but I'll warn you that many people find the pods to be a nuisance, creating more of a cleanup chore than they desire.

There are actually 2 species, southern catalpa (Catalpa bignonioides) and northern catalpa (Catalpa speciosa) whose ranges overlap throughout much of the country.  The difference between the two species is very slight and, for all practical purposes, they function the same way in the landscape, so I will just talk about them as one species, "catalpa".

Both of these species originally had a very small native range in the southeast U.S., which you can see in the Wikipedia links above, but both were widely planted as settlers homesteaded around the country.  I have been told that catalpa was one of the primary species used to "claim" a homestead and that it was widely used for fenceposts until osage orange (a.k.a. hedge apple) was discovered to be even longer lasting in that capacity.  The wood, although very light, does not rot rapidly when in contact with the soil.

Catalpa is also known as the "fishing worm" tree.  Apparently the caterpillars of the catalpa sphinx moth were commonly used as fishing bait in days gone by.  Supposedly these hornworm caterpillars can get numerous enough to defoliate the tree...but I have never observed a single catalpa "worm", so it's not something that worries me overly much about using the tree in the landscape.

Well, such as they are, those are my suggestions for bold texture in the prairie plant palette.  Next on the list will be fine and ferny textured plants...but I'll leave those for another post.

If you've got any other boldly textured prairie plants that you think would be good in a garden, I'd love to learn about them!


Gardener on Sherlock Street said...

That giant coneflower is an eye catcher. I don't think I've seen it available anywhere. It's cool.
I would take any of those milk weeds. I have a few small ones starting. Maybe this year they'll bloom!
I love catalpa trees but have no space to plant one.
Interesting about the sphinx moth caterpillars eating the leaves.
I suppose most of my garden plants fall in the medium range.

Gaia Gardener: said...

The giant coneflower is wonderful! I've seen it growing wild along highways in Texas, where it's also eyecatching.