Crimson clover

Trifolium incarnatum

Crimson clover is a green manure, a crop you grow for the soil. It adds nitrogen and covers the ground with leaves and red flowers that bees visit. Sow it from spring to late summer. Sown about six to eight weeks before the first frost, it lives through winter and grows on in spring.

Looking after it

Water: It needs little water. Keep the seedbed moist until the seedlings are up. After that, rain is usually enough. Feeding: It needs no feeding. The clover makes its own nitrogen and leaves it in the soil.

Cutting and digging in

Cut it down when it flowers, before it sets seed. Once cut to the ground, it doesn't grow back. Dig it into the top 25 cm of soil or leave it on the surface to rot. Then wait about a month before sowing.

What can go wrong

Clover seeding itself. If you let it set seed, it comes back as a weed among your next crops. Cut it while it's flowering.
Slugs and snails. They hide in the thick leaves and then move on to the next crop. After cutting, protect young plants and look for slugs on damp evenings.

Growing facts: RHS, UC ANR and seed-company sowing guides. Crimson clover care: RHS and SARE. pH: University of California SAREP.