Garden Q&A: How to make a container garden that attracts butterflies?
Q: I’d like to grow flowers that attract butterflies, but I can only grow in containers right now, in a mostly sunny spot. What perennials or annuals appeal to them?
A: Species in the mint (Lamiaceae) and aster (Asteraceae) plant families are fairly safe bets, often being highly attractive to butterflies, as well as to bees and plenty of other pollinators. Plants in the vervain and milkweed families are also appealing.
While native species are ideal, since some support multiple pollinator life stages or other wildlife, non-invasive non-native plants can also be used. Removing spent flowers (dead-heading) as plants go out of bloom can sometimes spur the production of another set of flowers, but this also impacts seed production, which might deprive you of a natural bird feeder for winter or the chance to propagate more of the same plant.
Some of these suggestions might be too tall for a typical pot, but there may be shorter cultivars.
Mint family favorites include native perennials like mountain-mints (Pycnanthemum), beebalms (Monarda), and obedient plant (Physostegia virginiana). Non-natives include anise hyssop (Agastache foeniculum), lavender (Lavandula), oregano (Origanum), ornamental sage (Salvia nemorosa and hybrids), and culinary mints (Mentha).
Popular native aster family perennials include aster (Symphyotrichum, Eurybia, and a few other genera), blazing-star (Liatris), sunflowers (Helianthus), Joe-Pye weed and kin (Eupatorium, Eutrochium, Conoclinium), sneezeweed (Helenium), and goldenrods (Solidago, Euthamia). Stokes’ aster (Stokesia) is native to the southeastern U.S., though not locally.
I’ve seen our cute, low-growing native lance-leaved frogfruit (Phyla lanceolata) attract pearl crescent butterflies, but it’s not widely sold. Its vervain family kin includes the native perennial blue vervain (Verbena hastata), which looks different from the verbenas widely grown as annuals, and the non-native lantana camara (from the American tropics), a woody perennial treated like an annual since it doesn’t survive our winters.
Several milkweeds (Asclepias) grow in Maryland, with butterfly weed (A. tuberosa) and swamp milkweed (A. incarnata) probably being the most widely available and suitable for confinement in a pot.
Other native perennials include tall phlox (Phlox paniculata), lobelia (Lobelia), and button eryngo (Eryngium yuccifolium). Non-native sedums (Sedum and Hylotelephium) can add upright or trailing accents to pots prone to drying out often.
Additional non-native annuals include starflower (Pentas) and zinnia (Zinnia elegans).
Q: What produces a lumpy, tan-colored clump on my mulch? It seemed to appear overnight, and it’s not like any animal scat I’ve seen.
A: This is a colony of a single-celled fungus-like (or amoeba-like) organism called a slime mold. The species of slime molds that are most often seen in gardens either look like what you’re seeing when growing over mulch — unappealing enough to be called “dog vomit fungus” — or like a cluster of exceptionally tiny mushrooms that cover a patch of grass blades. Maryland is home to a few dozen slime mold species, and if you’re curious, browse the gallery on Maryland Biodiversity Project.
They come together to reproduce after a period of wet weather. Growth progresses from a seldom-noticed slimy stage that branches out as it creeps — looking like spreading tree roots — to the crusty, buff-colored lump familiar to some gardeners. Slime molds feed on other microbes, so they do not pose a threat to plants because they do not infect them or cause disease. They generally disappear as fast as they appear, drying out and disintegrating.
No treatment is needed. If they are too abundant and objectionable, you can just scrape them off the mulch and toss the clump into a corner of the yard. If you see them reappearing in the yard and you water with a sprinkler, you might be irrigating the landscape too often, both to the delight of the slime molds and to the potential detriment of the plants themselves.
University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Extension” to send questions and photos.