Gadenin日本語Get the appBefore anything else: is it legal where you garden?
Bush clover is the common name for Lespedeza, a genus of leguminous shrubs and subshrubs, and the genus carries a real regulatory problem that has to be settled before you dig. Sericea lespedeza, Lespedeza cuneata, is a listed noxious weed in several US states, including Kansas, Colorado and Nebraska, and is treated as an invasive species to be actively removed across large parts of the Great Plains, the Midwest and the Southeast. It was widely planted decades ago for erosion control and forage, escaped, and now dominates prairie and pasture where it displaces native forage almost completely.
The shrubby ornamental bush clovers sold for gardens are different species, but they are not automatically in the clear. Shrub lespedeza and Thunberg's bush clover both set heavy crops of hard seed and both are flagged as invasive in parts of the southeastern and mid-Atlantic United States, where birds carry the seed into woodland edges and roadside ground. If you garden anywhere in North America, look up your state and county noxious weed list, and your state invasive plant council's assessment, using the botanical name on the plant label rather than the words on the tag. Do this even if a nursery in your area is selling the plant, because sale and legality do not always match.
If your species is listed, do not plant it, and do not move a division from a friend's garden either. If it is unlisted but flagged as invasive in your region, you can grow it responsibly by cutting the spent flowering stems off before the seed hardens and by pulling every self-sown seedling you find in the first spring after flowering. In a garden with a woodland edge, a creek or unmanaged ground next door, choose something else. Outside regions where the genus is a problem, it is simply a tough, late-flowering shrub with few demands.
Regulatory status is by state and sometimes by county, and it changes. Verify against your own state's current noxious weed list rather than a general gardening source before planting or sharing this plant.
The site: sun, drainage and deliberately poor soil
Give bush clover full sun, meaning at least six hours of direct light and preferably eight. In part shade the arching stems stretch, lean toward the light and flower thinly, and the whole plant becomes a floppy mess by the time the flowers arrive in late summer. There is no shade-tolerant way to grow this plant well.
Drainage matters more than fertility. Bush clover comes from dry hillsides, embankments and stony ground, and its roots rot in soil that stays wet in winter. A slope, a raised bed, the top of a bank, gravelly ground or the free-draining edge of a border are all ideal. Heavy clay that holds water for days after rain will kill it slowly over two or three wet winters, usually with the plant looking merely weak rather than obviously sick until it fails to come back one spring.
The instinct to improve the soil is the most common mistake. Bush clover is a legume: it hosts nitrogen-fixing bacteria on its roots and manufactures much of its own nitrogen supply. Rich, heavily composted, freshly manured soil produces long soft stems, lush leaves and disappointing flowers, and those stems flop under their own weight. Plant it into ordinary or frankly poor soil. If you have to amend anything, amend for drainage with grit or coarse sand, not for richness.
| Site factor | What bush clover wants | What happens if you get it wrong |
|---|---|---|
| Light | Full sun, six to eight hours minimum | Stretched leaning stems, sparse late flowers |
| Drainage | Free-draining, ideally sloped or raised | Slow decline over wet winters, then sudden failure |
| Soil fertility | Lean. No manure, no rich compost | Soft floppy growth, leaf at the expense of flower |
| Soil pH | Slightly acid to neutral, roughly 5.5 to 7.0 | Yellowing between the veins on very alkaline ground |
| Wind | Tolerates open exposure once established | Little damage. The stems are flexible by design |
| Space | Four to six feet (1.2 to 1.8 m) each way | Crowded stems, poor air movement, weak flowering |
| Root disturbance | None once planted. It resents being moved | Years of sulking, or death, after transplanting |
Planting a container-grown plant
Plant in spring, once the soil has warmed past about 50F (10C) and hard frost is behind you. Spring planting gives the roots a full growing season to establish before their first winter, which matters because a wet cold winter on an unestablished root system is what kills most young bush clovers. Fall planting works in mild-winter regions with sharply drained soil and is a gamble anywhere colder or wetter.
- Water the plant in its pot first Soak the rootball an hour before planting so it does not shed water later. A dry rootball set into damp ground can stay dry for weeks because water runs around it rather than into it.
- Dig wide, not deep Make the hole two to three times the width of the pot and exactly the depth of the rootball. Loosening the sides of the hole helps roots move outward. Digging deeper than the rootball invites settling, which buries the crown.
- Keep the crown at grade or slightly proud Set the plant so the top of its rootball sits level with the surrounding soil, or half an inch (1 cm) above it on heavy ground. A buried crown rots. This single detail decides more first-winter survival than anything else.
- Tease out circling roots If roots are wound around the outside of the rootball, pull the outer ones loose or score the sides shallowly with a knife in three or four places. Pot-bound roots that are left circling will keep circling and strangle the plant years later.
- Backfill with the soil you took out Use the native soil, unimproved. Firm it gently with your hands rather than stamping. Do not add fertilizer to the hole; a legume does not need it and rich backfill discourages roots from leaving the hole at all.
- Water deeply, then mulch off the stems Give it two to three gallons (8 to 12 liters) slowly to settle the soil around the roots. Mulch two inches (5 cm) deep with bark or gravel, pulled back a hand's width from the stems so the crown stays dry and airy.
The first year, and why you should not move it later
Water a new plant deeply once a week through its first summer in the absence of rain, more often in a heatwave or on sandy ground. Deep, infrequent watering drives roots down; light daily sprinkling keeps them at the surface where they are vulnerable. From its second summer onward, an established plant in open ground needs watering only in extended drought, and many gardeners never water it again at all.
Do not expect much in the first year. Bush clover spends its first season building roots, and top growth in year one is often half of what the plant will make in year three. The plant is at its best from about its third year, when it throws a full fountain of arching stems four to six feet (1.2 to 1.8 m) long and flowers along the whole length of them.
Site it as if the decision were permanent, because in practice it is. Bush clover forms a deep, coarse, woody crown that does not lift cleanly, and mature plants moved to a new position frequently die or take several years to recover. If you are unsure about a position, grow it for a year in a large container in a sunny place and watch the size before you commit it to the ground.
What to record at planting time
Write down the botanical name from the nursery label, not just the common name. Bush clover species differ enough in size, hardiness and weediness that a note reading only bush clover is useless two years later when you are trying to work out how big the plant will get or whether you should be removing its seed heads.
Note the planting date, the position with a rough measurement from a fixed reference like a fence post or a path corner, and the size of the plant when it went in. The position note matters because bush clover dies back to near ground level in cold regions and is invisible in early spring, which is exactly when people put a spade through it.
Also record what the soil was like when you dug the hole: whether it was stony, whether water stood in the bottom overnight, how deep the topsoil went. When a plant declines three years later, that note is usually the answer, and it is not something you can go back and measure once the shrub is in the way.