I have a small stewartia tree in my front yard surrounded by thick ornamental grasses. I have weed whacked the grasses and plan to expand the area around the tree with sheet mulching in a couple weeks. This is where my ideas run dry. I tried to find good companions for the tree but my searches didn't turn anything up. We just moved into this house and from the information I received from the previous owners the tree is only 2-3 years old. I was hoping someone here would have some ideas about what best to plant under a small tree that won't mess with its growth.
As this is an ornamental, not a crop, I wouldn't expect much information. What species is it? The wild ones I saw in Alachua County, FL, were wetland trees in "bays" (hardwood hammocks) & gum swamps (growing with water tupelo, sweetbay Magnolia, swamp bay [this was before Laurel Wilt invaded], and smaller numbers of baldcypress). As wetland is bad for houses and rife with mosquitoes, I assume you have another, probably Asian, species that prefers mesic conditions.
My suggestion is to look up what grows in its native habitat, stays low, tolerates the modest shade (?--well, the ones in FL were very columnar, though evergreen; it may depend on the species) and plant that (if also interesting or beneficial to you).
I will guess that like all other tea family plants I know, it needs acidic soil, at least some moisture, and prefers woodland organic matter if possible. Small types of Azalea (not indica) and Kalmia (not latifolia unless a dwarf type) also need that and are pretty at least in bloom (but very toxic). If the Stewartia is tall enough, you might try Lindera benzoin (spicebush) for tea and butterflies, but keep it full of small diameter twigs (unattractive to wood boring beetles) by pruning, since it is vulnerable to Laurel Wilt. Lowbush blueberries probably can't take the South, but Vaccinium darrowi (sp?), from the Southeast, is of similar size and cute though not productive (berries are edible). Gaultheria procumbens is a pretty evergreen groundcover, for wintergreen berries & tea. Gaylussaccia (sp?) baccata (eastern black huckleberry) is another low shrub type berry bush (large-seeded hence "grittier" blueberry, but bigger than V. darrowwi). Eastern dewberries (Rubus trivialis in the south, others like flagellaris northward) can be grown as fruiting (but prickly and aggressive) groundcovers. I know for trivialis you need two different clones for fruit. Many woodland/savannah wildflowers from the SE, unless they are specialists that grow on limestone outcrops, also like acidic conditions (pay attention to moisture difference though, which is where knowing the Stewartia species would help--the SE has wetlands but also sandhills full of cactus). Mertensia virginica is a very adaptable spring ephemeral that is a very helpful food source for bumblebee queens (you need bumblebees for pollinating anything in the tomato family later in the year). Avoid Conradina ssp.(Cumberland or FL rosemary) because they seem to be allelopathic. Mimosa/Schranckia strigulosa etc (catclaw mimosa) is a prickly but cute N fixing groundcover that kids like because the leaves snap shut if touched). If your soil is sandy, partridge pea (a self seeding annual) feeds the caterpillars of sulfur butterflies, fixes nitrogen, and feeds quail. Once the Stewartia is big enough, Centrosema virginiana (native butterfly pea, inedible) is a good way to extend the floral season--it is a lightweight with fairly sparse foliage so "shrub safe" and has large (for bean) lilac flowers over a long time through summer into early fall. But I am not sure acid-soil plants are really heavy nitrogen consumers. If you can get specific information (as opposed to "native to China/Japan," which is no more helpful than "native to the US") you could expand the options to what normally grows next door in Asia.
Use cardboard & woodchips to knock out the grass before planting anything new. Low stuff competes poorly with grass, and anything new usually competes poorly with established weeds.
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