They pollinate 90% of the flowering plants on earth; and they eat plants, the crucial first step in changing plant energy into the fats and proteins that feed hosts of other animals. In so doing, insects sustain Earth’s ecosystems. They truly are, in E.O. Wilson’s words, “The little things that run the world.”
Yet globally, insect populations have declined by 47% since 1974, a loss that translates into a decline in the very ecosystems that sustain all life on earth, humans included!
Why native plants? In study after study, it has been shown that native plants host many times more insect species than do non-natives.
Which insect groups are most important? In Nature’s Best Hope, author Doug Tallamy suggests selecting native plants that support two important insect groups: large, nutritious insects (think caterpillars of butterflies and moths) and bees. Caterpillars are the mainstay of most bird diets; and native bees perform the lion’s share of pollination.
Where can I find resources for host plants native to my area?
Planting a diversity of native plants chosen for their ability to provide food for caterpillars and flowers for nectaring bees, ensures not only a prairie garden filled with a diversity of insects and birds, but also a garden that contributes to a healthier environment. And it is all happening right outside our door!
Tallamy, Douglas W. 2019. Nature’s Best Hope: A New Approach to Conservation that Starts in Your Yard. Portland, Oregon: Timber Press.
Over the past few decades, there is an increased awareness of the importance of milkweeds for the life cycle of Monarchs. More and more people are planting these native wildflowers in their gardens. We closely monitor our milkweeds for monarch caterpillars and anxiously watch for the migrations in spring and fall. We can even track the populations on Monarch Watch. Milkweeds are vital to reversing the decline of this beautiful butterfly.
However, large populations of small yellow insects that typically cover the leaves and stems of the milkweed plants are threatening this important wildflower species. It seems like there are more of these tiny bugs every year. This year, we have seen large populations of them on our nursery stock and throughout the gardens. These oleander aphids (Aphis nerii) or milkweed aphids have become problematic.
Oleander aphids are not a native species, but were introduced into the U.S. on oleander. They suck the sap out of stems and leaves, can cause flowers and pods to abort, and can even kill plants. They concentrate milkweed toxins in their tissue more effectively than native milkweed aphids, which makes them toxic to beneficial insects. Like other species of aphids, their populations can explode in a short amount of time. When large populations are present, the plants will appear shiny due to the excretion of honeydew, which can also promote the growth of sooty mold.
As a milkweed gardener, what are your options?
Choose the right milkweed for your garden.
Stressed plants will attract more pests. Know your site and plant the right milkweed for your landscape. Swamp milkweed needs to be in a consistently moist area and butterfly milkweed naturally grows in areas with good drainage. Common Milkweed is very adaptable, but not for a formal garden. Plant common milkweed where they can spread and colonize a marginal area. There are many other species of milkweed that grow in sun to part shade and dry to wet. Continue to plant milkweed, but make sure it fits.
Encourage beneficial insects
With the milkweed toxins in the aphids, beneficial insects tend to leave these pests alone. This is a similar reason monarch caterpillars ingest the milkweed sap which makes them less prone to be eaten by predators. We have introduced parasitic wasp into the greenhouse to control these pests but that is not realistic outside that confined space such as your landscape. Lady beetles will typically eat aphids but they tend to shy away from these aphids.
Let the milkweeds grow naturally in unamended soil. Too much soil fertility will attract more aphids. These aphids reproduce more quickly on plants that have high nitrogen concentrations.
Be patient as you wait for the natural processes to work. Often, this is the hardest thing to do, because the plants are being adversely affected by thousands of these little pests.
When these cultural practices have been unsuccessful, it’s time to take a more aggressive approach. These are obviously not my first choices because they can also harm beneficial insects and even monarch caterpillars. You must use as a last resort to save the plant. Newly established milkweed plants may need some help the first few years until they get fully rooted. Mature plants typically can fend off most of these pests.
We have resorted to squishing the bugs on nursery stock. These smaller plants are easier to manage by simply squeezing the affected parts of the milkweed plant between thumb and forefinger and drag along the stem. Use a glove or paper towel as you squish because it will get messy.
Another option is to squirt the plant with a strong blast of water especially after you have squished the bugs. Use a spray bottle of water or a jet of water from a hose. Focus the water on just the infested areas so other beneficial insects are not disturbed.
The least optimum choice is to spray with horticultural soap or oil. Concentrate the spray just on the aphid colonies. Use a piece of cardboard placed below the colony of aphids to minimize drift to other parts of the plant. Again, this is a last resort option but may be necessary to save newly established milkweeds.
Milkweeds are beautiful and essential native wildflowers. They are under assault by these non-native pests. Hopefully, you can get your milkweed plants through this onslaught of oleander aphids because they are so important for monarchs and other pollinators.
Do you have an out-of-the-way plot of ground that needs to be vaccinated from the maladies of soil erosion or a lack of biological diversity? Is this planting area safely physically distanced from other more manicured areas of your landscape? Would you like 2020 to be remembered for something other than COVID-19? If you answered “yes” to any of these questions, I have a selection of very easy-to-grow native plant species that will establish your prairie landscape area faster than a coronavirus infects a church choir.
Brad’s PPE (Prairie Pandemic Elections)
Illinois bundle-flower (Desmanthus illinoensis) – a nitrogen-fixing legume with seed heads that are as attractive as its flowers
river oats (Chasmanthium latifolium) – the only shade-oriented species of the bunch that originates from stream corridors of Eastern Kansas
beebalm (Monarda fistulosa) – the flowers attract bumblebees and the vegetation can be used make mint tea
common milkweed (Asclepias syriaca) – this favorite host plant for the monarch butterfly also has very sweet aroma when flowering
gray-headed coneflower (Ratibida pinnata) – stunning splashes of yellow when this species blooms in mass
compass plant (Silphium laciniatum)
rosin weed (Silphium integrifolium)
cup plant (Silphium perfoliatum)
prairie dock (Silphium terebinthinaceum)
The genus Silphium offers four very hearty species that have so much to offer. Learn more about these species from a previous blog post.
western ironweed (Vernonia baldwinii) – this is the taller and more robust cousin of our plant sale favorite ‘iron butterflies’ ironweed
tall joe-pye weed (Eupatorium altissimum) – few species will attract more pollinators than this Eupatorium
brown-eyed susan (Rudbeckia triloba) – so beautiful and so invasive
tall thistle (Cirsium altissimum) – not all thistles are bad as I discuss in an earlier blog post
Canada goldenrod (Solidago canadensis) – goldenrods are famous for their color and pollinator attraction in late summer and few are heartier than this species
Maximilian sunflower (Helianthus maximiliani) – learn more about this and other sunflower species that could be considered good pandemic picks in an earlier blog post
See an earlier post I wrote about these late summer blooming “undesirables” and all the loads of insects they attract to our Arboretum landscape.
Prairie Ecosystem vs Prairie Gardening
In a diverse and thriving prairie ecosystem where these native species typically reside, a dense matrix of competitive prairie grasses and grazing animals help keep them in check. You could say that the prairie plant community has a herd immunity against these aggressive, super-spreader species.
But when you plop these species into a nutrient-rich, urban prairie garden with mulch and plenty of moisture, they grow seemingly with reckless abandon. They don’t have the same competitive prairie environment or grazers regularly eating them back to keep them in check. They spread quickly with rapidly expanding root systems and prolific seed production. These pandemic picks are long-haulers that will quickly (within a five years) take over slower and lower growing species, and you won’t need contact tracing to know where they came from. Therefore, we’ve learned (the hard way from some of our thankfully forgiving members) that these pandemic picks with their tall, rank growth do not belong in a small, more manicured garden.
So, given this information, you may ask…why recommend these pandemic picks that would make one symptomatic of a foolish gardener? Or, to put it more bluntly, WHO in the world is this CDC (Center for Dumb Consultation) that is giving you this advice!? Dyck Arboretum, of course!
The species I’m recommending provide colorful, aesthetically-pleasing blooms, soil erosion control, interesting vegetation, host plant food for caterpillars, and loads of nectar for pollinators. These species are extremely drought tolerant and will survive fine without care from you. And as an added bonus, they provide hearty competition for and crowd out annual plants like giant ragweed, a pollen emitter that makes you want to don your N-95 mask this time of year!
The major disclaimer I will offer and the key to being happy with these pandemic picks in your landscape is choosing a remote place where they can all be quarantined together. The more physical distance you can give this cluster planting location, the less likely their seeds are to invade more manicured areas of your prairie landscape. The only care this planting needs is an annual mowing/cutting in winter or early spring. Add some flammable tall grasses to the mix like big bluestem, Indian grass, and switch grass, and you can burn it annually instead.
To learn more about these species, visit the Kansas Wildflowers and Grasses website. A handful of these species are available through our FloraKansas native plant sale. Zoom on over to Dyck Arboretum in the coming days of September 10 (for members) and September 11-13 (for general public). All of these species can be found on our grounds. Bring a paper bag, catch me at FloraKansas, and I’d be happy to show you where these species can be found and give you permission to collect seed.
Get in early on this pollinator-friendly planting trend now as it may soon go viral!
As the growing season winds down, there is still plenty happening in the garden. I like to think of this time as fall’s crescendo, bringing the prairie’s annual symphony to a high point before falling into dormancy. The asters are beginning to show a few blooms while the goldenrods and sunflowers are adding a bit of sunshine to the landscape and roadsides.
Fall is a great time to glory in the many textures and forms of our native grasses too. Every phase of the garden is beautiful, but I have come to appreciate autumn the most.
Life is a cycle
Each fall, the garden reminds us that we have come full circle. From winter’s dormancy to lush spring growth through summer’s blazing hot days to fall’s crescendo of color and texture, the prairie has put on another spectacular display. Now as flowers fade, the grasses will show their true colors and everything slowly becomes lifeless and brown. These forms, textures and seedheads standout in the landscape, extending the interest in the garden into the winter once again.
So much is happening in the garden right now. Plants are storing energy in their roots for next year. The browns and yellows of the foliage mean this process is complete. Actively growing plants are only alive at or below the soil line. This transformation can be stark, but I think it can be quite attractive.
Just because the plant has gone dormant, doesn’t mean you need to remove it. I challenge you to leave it up through the winter. A prairie garden in the fall and winter with all its forms, textures and muted colors has a unique beauty that should be savored. Let it be. Don’t be too quick to send it to the compost pile.
Dormancy is important for the plants, but so many other things benefit from these plants this time of year. Insects of all types overwinter in garden litter and tufts of grasses. Inside plant stems and at the base of grasses, insects and butterflies at different life stages are safely harbored for the winter. This is why it is so important to leave these dormant plants through the winter. In the spring, we cut these plants down but leave the stems as mulch. These dormant insects will wake from their winter slumber to pollinate for you next year.
Songbirds that overwinter will find flower heads such as coneflowers and sunflowers welcome food sources. As the winter deepens, food becomes much more scarce. These nutritious seeds are just what these birds need to get them through the coldest months. Again, you can cut them back in February or March as you prepare for spring. Remember to leave as much as you can on the ground as natural mulch. Don’t carry all those beneficial insects away from the garden.
Fall’s Crescendo into Dormancy
Fall is a reminder that natural processes are at work. Simply understanding how important this process of dormancy is to the prairie and to wildlife should guide how you manage it. Take note how the stark contrast of the native grasses in texture, form, and hues of color against spent wildflowers gives the prairie landscape a unique beauty all its own. Whether you are taking advantage of the cooler temperatures to work on an outdoor project or just enjoying the plants and wildlife, it’s a great time to be on the prairie. I love this time of the year.