In Praise of Bare Soil

Wildflower Garden May 8, 2019

My "wildflower garden", a term I use loosely, is developing as I've added more flowering plants. Although some of these may eventually decline as summer approaches, right now, everything is doing quite well. The two species of tickseed I've added (C. leavenworthii and C. lanceolata) are in bloom and attracting the attention of small carpenter bees in the Ceratina genus. The native butterfly milkweed (Asclepias tuberosa), of which I've planted six specimens, has begun to bloom and this has attracted the attention of monarch butterflies. The blooms are getting pollinated at the same time that the butterflies are laying eggs on them. Although butterfly milkweed is not considered to be a major host plant for monarchs because they lack the milky sap that protects their caterpillars, I find that they are used when in bloom. Mine certainly are right now and I've moved a few of the caterpillars to other species of milkweeds in my landscape in hopes that I'll get butterfly milkweed seed to propagate from. I do not like growing plants from cuttings. Time will tell if any of the pollinated flowers develop full seed pods, though I am hopeful. The native wild petunia (Ruellia caroliniensis) also is blooming, but it has not drawn the attention of much so far.
Context is always important in designing a pollinator garden. Over the years, I have found that plants have different relative value depending on the location of the garden. There is no plant that is universally equal in its attributes as a nectar source. The wild petunia is a classic example. Nearly 30 years ago, I planted my first wildflower landscape and I collected data with my intrepid administrative assistant on butterfly use. There were more than a dozen species of native wildflowers in bloom at the time and we collected data on number of visits by butterfly species and length of time for each of those visits. After more than a year, the clear favorite in this landscape for nearly all butterflies was wild petunia. This was not the case, however, in my own landscape that I planted only five miles away and it's never been repeated in any landscape I've installed since. If anything, it's a testament as to why having a diversity of flowering plants is important.

Another view, same day. Right now, there is a lot of bare soil

All that said, my purpose of writing today is to point out the importance of the bare spaces - not the plants themselves. In its present state, my planting area is almost as much bare soil as it is plants. That will change as I add more plants and as I let those I've planted reseed and multiply. I can install the framework of this landscape, but I'd be foolish to think that it will remain ordered as cleanly as it is right now. Plants will eventually find their own "sweet spot" in the landscape. These seedlings and suckers are often stronger than their parents. In the years ahead, this area will morph and change into what it wants to be - designed by nature more than by myself. That's the way it should be.
There are two important elements to this, however. I weed daily as the plants I have not invited in emerge from the seed bank and I've not used mulch.  Weeding is a daily event for me. Exposing the bare soil that was beneath the original sod has encouraged all the weed seeds to give it a try. I've left the toadflax (Linaria canadensis) and the mock bishop's weed (Ptilimnium capillaceum) that came up in profusion. Both are annuals and they will die shortly. The former provided an important nectar source in the earliest days of this planting. The latter is a host plant for eastern black swallowtails and, though none have visited, it was important to have it available should they have made their appearance. I have other plants now that the mock bishop's weed is in decline and both of these "weeds" will make an appearance again next spring.  The other weeds that keep trying to establish themselves are weeded as soon as I notice them. It is always easier to eradicate each one when its root system is just getting established. I do not care if these weeds are "native" or not. They are not welcome as they do not provide the ecological values that I require.
The bare dirt makes the emergence of weeds more likely, but it is an absolute essential part of this landscape. I detest mulch in areas devoted to wildflowers. It impedes reseeding and it is anathema to the ground-nesting bees that I hope to provide nesting habitat for. Too often, bare ground is looked at as a gardening "failure."  It shouldn't be. I find beauty in bare soil as much as I recognize its utility. As my landscape continues to mature, the amount of bare soil will decrease, but I will make sure that there is always some available. Ground-nesting bees require it, birds will use it to dust themselves, and it will encourage weeds... I don't mind the weeding. It gives me time in my garden and it is a necessary "evil" of what I'm trying to accomplish. Bare dirt is a thing of beauty. Embrace it in your own landscapes.