Discovering Host Plants

My phone is chock full of caterpillar photos. It seems I am constantly stooping down to examine another caterpillar, and to document what it is eating. I am a big fan of all insects, but especially these charismatic transformers. With their plump bodies and endless colors, it is not hard to see why people are becoming more interested in attracting them to the garden.

Viceroy caterpillars can be hard to spot. They disguise themselves as bird poo to appear less appetizing, and it works!
This one was spotted just off the sidewalk at the Arb eating willow leaves.

Host plants are a key part of that process. Caterpillars of all kinds often have a specific food plant or plant family that they need to survive. While I am familiar with monarchs on milkweed and swallowtails on parsley, there is a whole world of interesting host plants out there to utilize in the landscape.

Potluck

My house cats can be picky eaters, but caterpillars are even worse. Many of these little creatures can only feed on a handful of plant species. Their mothers may have to fly miles and miles to find the right plant to lay her eggs on. That is why it is so important to support the native insects of your area by gardening with the native plants they have evolved with for millennia.

Recently I added a few new host plants to my mental list of must-haves for caterpillar habitat.

  • Aspens and willows for viceroy butterflies
  • Primrose and lythrum for sphinx moths
  • Baptisia for broom moths
  • Sumac for spotted datanas
A group of white-lined sphinx moths devoured a primrose patch. They also like to chow down on winged lythrum (Lythrum alatum), a great native plant for wet areas.
Genista broom moth caterpillars (Uresiphita reversalis) are a cheery shade of yellow. They love Baptisia and can make the plants look quite ragged. But, by the time these caterpillars are feeding heavily in midsummer, the Baptisia has already bloomed and is done for the season anyway.
These spotted datana (Datana perspicua) caterpillars are gregarious feeders, meaning you usually find them in groups with their siblings. They munched away on this aromatic sumac (Rhus aromatica) for a few days, and tripled in size!

Appreciate, Don’t Hate

As my knowledge of host plants grows, so does my appreciation for native plants and the intricate ecosystem they support. I am so encouraged to hear more people calling them friends rather than foes, and wanting to identify and observe rather than squish and poison. It is always best practice to pause before sprinkling that pesticide – your garden will thank you, since most caterpillars do more good than harm. Changing our perspective about caterpillars, and all insects, is key to maintaining a functional, healthy food web. If you are interested in finding more caterpillars in your Kansas landscape, reach out to the staff at Dyck Arboretum for consultation, follow our Facebook and Instagram accounts for educational content, and mark your calendars for next spring’s FloraKansas fundraiser!

Last Update on Buffalograss Seeding Experiment

It has been almost a year since our buffalograss seeding experiment began.   In this new approach, we planted the buffalograss seeds along with annual ryegrass in the fall or early winter.  In theory, the annual ryegrass, a cool season grass will germinate and hold the soil through the winter.  The buffalograss seeds will work their way into the soil with the natural freeze/thaw of the soil throughout the winter.  These seeds will then germinate on their own the following spring with annual rainfall and warm 60 degree soil temperature.

Last fall I prepared the soil as if I was planting fescue so the annual ryegrass seed would germinate with daily watering.  This loose seed bed helped the annual ryegrass to germinate in about a week or ten days.  This method flipped the traditional buffalograss seeding upside down.  Typically, I have areas prepared to plant buffalograss in May and June.  Buffalograss it is a native warm season grass that needs to be planted when soil temperatures are above 60 degrees.

Update

I have been pleasantly surprised.  The little buffalograss seedlings have started to spread in amongst the crabgrass and knotweed.  I believe it will begin to overpower these weeds and completely cover the areas next year. 

Buffalograss seedling that have started to spread

I may look at putting a preemergent herbicide down next spring to give the buffalograss less weed competition.  This is primarily to control summer annuals such as crabgrass and foxtail. Barricade (prodiamine), Pendulum Aquacap (pendimethalin), Dimension (dithiopyr), Specticle (indaziflam) are recommended pre-emergent herbicides on established Buffalograss stands. Read and follow the chemical label application instructions for best results.  Pre-emergent herbicides can also be applied in the fall to control that pesky weed, little barley.

When asked if I would do this buffalorass planting method again, I would say yes.  For small areas of 1000 sq. ft or less, it makes sense and saves so much water.  For larger areas, I think it is a toss-up.  I think it will be successful either way.  Of course, summer seeding take at least daily watering for the first 10-14 days to get the seed to germinate.  For large areas, this obviously requires so much water because the soil dries out quickly with wind and heat.  I think you can be successful with either method but I really liked using less water overall. 

We encourage people to use buffalograss in areas that receive at least six hours of sunlight each day throughout the year.  Newer varieties are vigorous growers and require little to no water once established. Compare that to a traditional fescue lawn, which needs one to two inches of moisture per week to keep it alive in the summer. These newer buffalograss forms stay green longer in the fall and green up earlier in the spring.  If kept relatively weed free, they require less frequent mowing. Buffalograss needs little to no fertilizer and will reduce your overall maintenance.

Small buffalograss seedling

Reasons to Leave Ornamental Grasses In Winter

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

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
Switchgrass capturing snow

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

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

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

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. 

Missouri Black-eyed Susan

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.

Brown-Eyed Susan

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’. 

Rudbeckia ‘American Gold Rush’

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.

Plant Profile: Columbine

As I put together lists of plants according to the season that they bloom, I often come up short on spring blooming plants. In a prairie, many plants are slow to get growing in the spring until warmer temperatures spur growth.  One of the more tried and true spring blooming perennials I like to include on my lists, especially in partial sun areas, is Aquilegia canadensis, or columbine.

The Columbine flower

Columbine is one of the most popular plants for shade.  However, it grows quite well in sunny spots with morning sun and afternoon shade.  This spring blooming (May-June) woodland native is essentially two flowers in one! It has an inner yellow flower surrounded by a delicate spurred outer flower. These nectar-rich blooms are a favorite of butterflies, other pollinators, and even hummingbirds in the spring. 

The typical red/yellow flower of our native columbine

The name

Its scientific name and common name reference a couple of birds. The genus name Aquilegia comes from a combination of the Latin word “aquila” (meaning eagle for the five spurs resembling an eagle claw) and the Latin word for “columba” (meaning dove, for five doves nestled together).

The leaves

The blue-green foliage elongates in the spring, with reddish stems topped by the elegant flowers. After blooming the stems dry. I like to cut back these flower stems to the rosette of foliage.  If you leave the flower stems, the brown capsules, full of black seeds, will fall and seed themselves in your garden for next season. Occasionally, the foliage will be infested with leaf miners. Simply cut the foliage back to remove the unsightly leaves and let it regrow a new rosette of lobed leaves. Then you can distribute the seeds in other areas where you would like some more plants.

Caring for Columbine

Columbine is easy to establish in partial sun to full shade conditions. It is quite adaptable, growing in wet to medium dry soils.  It makes a nice combination with golden alexander, blue star, false sunflower and sky blue aster. A pink version of Aquilegia canadensis was actually discovered in Marion County, Kansas by the late Al Gantz and introduced by Dyck Arboretum of the Plains.

Beautiful pink columbine flower from Marion County, Kansas

As you put together your plant list for a design or matrix planting, don’t overlook the obvious. Columbine is a wonderful woodland wildflower that should be brought out of the shadows. Include it in your design as a filler to add an early pop of color in the spring in your partial shade/sun site.

Army Worms

The Arboretum is under siege! An army has invaded, demanding we relinquish our lawns! Army worms, that is. These pesky creatures can cause major damage, and they unfortunately have a taste for fescue. Last week we came upon a sidewalk full of worms, crawling out of the lawn in search of more food. The grass was a sea of them, their tiny movements making it seem like the ground was alive.

Close up of a fall army worm Spodoptera frugiperda.
Army worms have a distinctive ‘Y’ marking on their heads
and are usually found feeding in groups.

To Spray or Not to Spray

I am always a big advocate of lassez-faire when it comes to controlling insect populations. After all, “plants are meant to be eaten”, right? And every insect has its place in the food web to keep our ecosystem thriving. I say this every time our members call asking about why their coneflowers have holes in the leaves, or why their Zizia has been defoliated. I tell them not to panic, that bugs are good to have in a garden, and that with enough good habitat natural predators will help keep the populations in check.

But when populations explode overnight, it can rightly cause concern. Native perennial flowers have deep tap roots that can reach 10 ft deep and beyond, which means they easily recover from a bit of nibbling. Fescue does not. The root zone is often less than 2ft, and in the heat of summer it can get even shorter. These little bugs can cause big damage! But luckily they rarely kill the grass. According to KSU Extension and Research, they don’t usually eat into the crown of the plant, rather move on to more tender greens. This means the plant can regrow and recover once they leave.

Fall armyworms seldom kill grass ---- rather, than nubbing a plant
down to the crown and growing point, larvae will select a more tender adjacent grass
blade to feed upon. Of course, under heavy feeding pressure, larvae may be forced to
feed deeper down on a plant, but usually, when the food supply becomes scarce or
"tough", the larvae will move "in mass" to adjacent areas where there is a "fresh stand"
of food to feed on.

- Kansas State University Agricultural Experiment Station and Cooperative Extension Service
Army worm damage looks a lot like drought stress at first glance. The grass turns patchy and brown.
This lawn was green and lush 72 hours before this photo was taken, an example of how quickly these little worms can feed.
Fescue at the Dyck Arboretum, beginning to resprout on August 18, 3 to 4 days after the army worms have finished feeding.
Stay tuned for updates in the coming weeks.

Use a Targeted Pesticide

Insecticides containing acephate and spinosad are effective at killing caterpillars, but we opt for friendlier treatments since these are known to harm the bees, birds and butterflies that call the Arboretum home. To avoid unnecessary kill off of non-target insects, I use Bt: Bacillus thuringiensis. This is a biological pesticide that uses bacteria to infect the gut of the army worm. In the alkaline gut environment of insects, it turns toxic and gives them a terminal tummy ache. We also use this around the Arboretum to keep bagworm populations in check when they start to overwhelm our cedar trees. According to current research on Bt, it is non-toxic to humans, pets, birds, and fish. It also has a short life once sprayed, which means reapplication is necessary, but also ensures you aren’t killing more insects than you intended to.

Monoculture Dilema

This is the precisely the problem with monoculture lawns. They require consistent maintenance, chemical and physical, to achieve that uniform, western European ideal of ‘perfection’. As we consider seeding new grassy areas of the Arboretum, we may be looking to a fescue mix, or a seed mix that includes sedges and native grasses together. This means that if an infestation comes along, hopefully not all species in that mix will be palatable and leave some green behind while the rest of the species recover.

If you see a few army worms here and there, don’t panic. Only large populations require a chemical response. But to those of you who will encounter them by the millions this summer like I did, good luck!

Seeded Prairie Checkup

I recently did a seeded prairie checkup to see how our December 2020 sidewalk planting described in the earlier blog post “Seeding After Disturbance” is doing. I’ve been informally monitoring it regularly since spring and have been encouraged by the progress I’ve seen.

Sidewalk edge seeded planting site this week on 8/10/21
The same planting site on the day it was planted 12/28/20 w/ planters Janelle and Kendra

Good Germination

We’ve been lucky with the weather since this planting. Conditions to promote good seed germination have been excellent. Remember the deep freeze we had in February? While it tested our human resiliency and strained our heating bills, it was good for this seeded prairie. Adequate precipitation and freeze/thaw action commenced throughout February and March. These conditions helped work the seed down into the soil while also breaking down their seed coats to help prepare them for germination.

Warmer temperatures along with rains in April and May promoted good germination. Identifiable prairie seedlings from the planted species list identified in the earlier blog post were evident amidst the expected seedlings of annuals like ragweed, sunflower, and foxtail.

Annual sunflower, giant ragweed, and foxtail grass serve as a shading nurse crop for tender, young perennial prairie plants

Thanks to the planting areas’ proximity to a water spigot, I was able to do some supplemental irrigation during the hot, dry weeks of late June and early July to keep the new seedlings from burning up while the seedling roots were small. But periodic rains in July and early August along with mottled shade from the nurse crop of sunflowers and annual grasses provided the conditions needed to help the prairie seedlings get well established as we head into fall.

Species Identified

A brief perusal of seedlings during this week’s seeded prairie checkup helped me find and photograph 14 of the 43 species that were part of the Prairie Moon Nursery seed mix. My prairie seedling identification skills are rusty, but I was able to identify the following seedlings to at least genus and some to species.

Seedlings of these identified species are thick throughout the planting and I’m confident that a good number of the rest of the 43 species in the mix will also show up eventually.

Weed Management

Typical management for a less-manicured seeded planting is simply to mow it a couple of times during the growing season to keep annuals from going to seed. Since such an approach for a higher profile area near the visitor center may look a bit scalped and perhaps not as appealing, we are taking the approach of cutting or pulling stems of the annuals. It is more labor intensive than mowing but not an unmanageable approach for small sidewalk edge planting, and regular volunteer, Gerry Selzer, has cheerfully embraced this task.

This weedy sidewalk edge vegetation is shading and hosting a variety of prairie seedlings underneath
The rare and coveted Gerrius selzeranii

Attracting Insects

One of the main reasons for planting this diverse wildflower seed mix in addition to adding pretty splashes of flower colors, is to attract insects and biological diversity to our sidewalk edge prairie beds. In two or three years, these planted species will be flowering and attracting insects with their flower nectar and host plant vegetation. I look forward to engaging school kids and teachers with regular investigations of these sidewalk edges to learn more about relationship between prairie plants and insects.

A new black-eyed susan is already playing host to caterpillars, possibly of species of checkerspot butterfly

Overall, I’m pleased with the progress of this planting as seen during this seeded prairie checkup. Days are getting shorter and we are almost to the cooler months of this planting’s first year when I can be pretty sure that these young prairie seedlings will have deep enough roots to survive about any weather conditions. Stay tuned for future updates about the development of this planting and consider how you too might add a seeded planting somewhere in your landscape.

Coneflowers: A Lesson in Host Plants

Coneflowers are so emblematic of the prairie. I love to include these prairie denizens in many of my designs. They are quite adaptable and I love the yellows, purples and pink colors of the true natives as they bloom during the summer.  The new cultivated varieties are attractive too. A mass of coneflowers with little bluestem make a nice combination by providing color and texture through the growing season. But right now, many of the plants are full of little black or brown caterpillars that are using Echinacea and Rudbeckia as their food.

Coneflowers as host plants

We are getting calls from our members and customers, and are seeing damage on our plants as well. Coneflower leaves are blackening, getting holes and disappearing. Contrary to how you may feel, this damage is an indication that your garden is functioning properly. Host plants are the vital food source that caterpillars live on. Adult butterflies will seek out these plants to lay their eggs on because they know that the caterpillar cannot travel far and will not survive if placed on a plant that they cannot eat. These caterpillars will eventually turn into checkerspot butterflies or a relative in that family. 

Think differently about your landscape

One of the goals of any garden – besides beauty – is to have pollinators in your garden. Sometimes they might not immediately be in the form you desire. Sometimes pollinators or their caterpillars may eat your plants or deform them.  Don’t be too hasty to spray or remove the culprits. They are doing what comes naturally to them and it is often better to leave the insect. These insects are fantastic food for fledgling birds as well.

Understand the life cycle

The caterpillars eating your coneflowers will make cocoons in a week or so and then turn into butterflies.  We must learn to embrace these caterpillars and accept some damage. The coneflowers will eventually recover. The tradeoff is that we create habitat suitable for butterflies to complete their life cycle. The “ugly, hairy” caterpillars will morph into beautiful butterflies that are equal to the beauty of the flower. 

The key to a successful butterfly garden is to plant both nectar and host plants, so that the butterflies will have a food source in all stages of their life cycles. We often design our landscapes as nectar sources and forget that these pollinators need host plants too. So as you design your landscape, include flowering plants that produce nectar and also double as host plants.

Other host plants

  • Black Eyed Susan (Rudbeckia hirta) Host plant for: Silvery Checkerspot, Gorgone Checkerspot, Bordered Patch butterfly
  • Aster spp. Host plant for: Pearl crescent, Painted Lady and more
  • Coneflower (Echinacea spp.) Host Plant for: Silvery Checkerspot and more
  • Hollyhock (Alcea spp.) Host plant for: Painted Lady, Common Checkered-Skipper and more
  • Golden Alexander (Zizia aurea) or Dill (Antheum graveolens) Host plant for: Black Swallowtail, Anise Swallowtail and more NOTE: The Black Swallowtail will feed on any plants within the Parsley family.
  • Sunflower (Helianthus spp.) Host plant for: Silvery Checkerspot, Painted Lady and more
  • Milkweeds (Asclepias spp.) Host plant for: Monarch
  • Mallow (Malva spp.) Host plant for: Common Checkered-Skipper, Gray Hairstreak , Painted Lady and more
  • Violet (Viola spp.) Host plant for: Great Spangled Fritillary, Variegated Fritillary, Meadow Fritillary and more