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Bush clover can be increased three ways, and they are not equally good. Softwood cuttings taken from the current season's growth in early summer root readily and give you a plant identical to the parent, which matters if you are propagating a plant whose flower color or habit you specifically like. Seed germinates well once the hard coat is dealt with but gives variable seedlings and, in regions where the genus is invasive, raising seedlings is exactly the behavior to avoid. Division works on plants up to about four years old and becomes progressively less viable after that as the crown turns into solid woody knuckle.
Before propagating at all, apply the same test as for planting: if the species is a listed noxious weed in your state, do not increase it, and do not pass plants to other gardeners. Propagation is how ornamental lespedezas move around a region, and a gift plant is the most common way a listed species ends up in a garden whose owner has no idea what they have.
For most gardeners the answer is cuttings. They are quick, the success rate is high without special equipment, and one afternoon in early summer yields more plants than a household garden has room for.
| Method | When | Time to a plantable plant | Reliability |
|---|---|---|---|
| Softwood cuttings | Early summer, from soft current-season shoots | Rooted in four to six weeks, plant out the next spring | High |
| Semi-ripe cuttings | Late summer, from firming shoots | Rooted by fall, overwinter under cover | Moderate |
| Seed | Sow in spring after scarifying | Flowering plant in two to three years | High germination, variable offspring |
| Division | Late winter at the time of the hard cut | Immediate, if it takes | Good on young plants, poor on old ones |
| Self-sown seedlings | Found in spring near the parent | Immediate | Easy, but a warning sign in invasive regions |
Softwood cuttings, step by step
Take the cuttings in early summer, when this year's shoots have length but are still soft and flexible and snap cleanly rather than bending. Work in the cool of the morning, and get the material into a bag and out of the sun immediately; soft bush clover shoots wilt within minutes on a warm day and a wilted cutting rarely roots.
- Cut shoots four to six inches (10 to 15 cm) long Choose non-flowering side shoots from the outer part of the plant. Cut them longer than you need and trim them properly on the bench. Drop each one straight into a sealed bag with a spray of water inside.
- Trim below a leaf joint Recut the base cleanly just below a node, so the finished cutting is three to four inches (8 to 10 cm). Roots form most readily at the node. A ragged cut made with blunt pruners crushes the tissue and invites rot.
- Strip the lower leaves and reduce the rest Remove all leaves from the bottom half of the cutting. If the upper leaflets are large, cut them back by half to limit water loss. Leave at least one full set of leaves; a leafless cutting has no engine.
- Dip in rooting hormone Dip the base in rooting powder or gel and tap off the surplus. Bush clover roots without it, but hormone speeds it up and improves the strike rate noticeably on later, firmer material.
- Insert into a gritty, low-nutrient mix Use half perlite or coarse sand to half peat-free compost. Push cuttings in to a third of their length around the edge of a small pot, five or six to a pot, with the leaves not touching each other. Water once to settle them.
- Cover and keep warm, bright and out of direct sun Put the pot in a propagator, or in a clear bag held off the leaves by sticks. Aim for 65 to 75F (18 to 24C). Vent for a few minutes every couple of days and remove anything that has gone brown or slimy.
- Pot up once rooted Expect roots in four to six weeks, shown by resistance to a gentle tug and new growth at the tip. Pot each rooted cutting into its own small pot in gritty mix, harden it off gradually, and overwinter it frost-free in a cold frame or unheated greenhouse.
Do not pot rooted cuttings into rich compost. Young bush clover in a high-nitrogen mix produces soft growth that fails to harden before winter, which is the most common reason a cutting that rooted perfectly is dead by spring.
Seed: the hard coat is the whole problem
Bush clover produces small single-seeded pods after flowering, and the seed coat is hard and water-impermeable. Sown untreated, most of it simply sits in the compost for a year or more waiting for the coat to break down. That same hardness is why the genus persists so stubbornly in soil where it has escaped, with viable seed banking for years.
Break the coat before sowing. The simplest method is a hot water soak: pour water that has just come off the boil over the seed, let it stand as the water cools for twelve to twenty-four hours, and sow the seeds that have visibly swollen. Alternatively nick each seed coat with a craft knife or rub it between two sheets of medium sandpaper until the surface dulls, being careful not to cut into the seed itself. Treated seed germinates in one to three weeks at 65 to 75F (18 to 24C).
Sow a quarter inch (5 mm) deep in a gritty seed mix, keep it just moist rather than wet, and prick the seedlings out into individual pots as soon as they have their first true trifoliate leaves. Seedlings hate root disturbance later, so move them early and only once. Expect first flowers in the second or third year. Note that seed-raised plants vary in vigor, habit and flower color, and some will be leggier or coarser than the parent.
Division, and dealing with self-sown seedlings
Divide only young plants, up to about four years old, and do it in late winter at the same time as the hard cut, when there is no top growth in the way. Lift the whole plant, look for natural separations in the crown where distinct woody shoots have their own roots, and cut it apart with a sharp spade or a saw. Each division needs a real share of root, not just a stem with a stump. Replant immediately at the same depth, water in, and expect a season of slow growth before it looks like a plant again.
On older plants, do not attempt this. The crown becomes a dense woody mass with a deep coarse root system that breaks rather than splits, and the usual outcome is a dead parent and dead divisions. If you want more plants from an old specimen, take cuttings instead.
Self-sown seedlings appear in spring near an established plant, especially in gravel, path edges and the loose soil under mulch. In regions where the genus is invasive, these are not a bonus, they are the problem: pull every one while it is small and before it has built the deep root that makes it hard to remove, and cut the parent's spent flowering wands off before the pods harden so there is no next crop. Where the plant is well behaved, a couple of seedlings potted up is the easiest free plant in the garden.
What to record when you propagate
Label every batch at the moment you make it with the date, the method, and the parent plant. Cuttings and seedlings are indistinguishable in a pot three months later, and the difference matters: a cutting is a copy of a parent you chose, a seedling is a lottery ticket. Unlabeled propagation material is the reason gardens end up full of plants nobody can identify.
Record the strike rate: how many cuttings you stuck and how many rooted, together with the date you took them. Bush clover cuttings have a fairly narrow ideal window in early summer, and two or three years of dated results will show you your own local window far more precisely than any general advice about early summer can.
For seed, note which scarification method you used and the germination percentage and timing you got. Hot water and nicking do not always perform identically on seed from different plants or different seasons, and a short record saves you repeating a method that did not work for you.