Mammoth Red Clover Organic Cover Crop Seed

Scientific names

Medicago sativa (alfalfa), Melilotus officinalis (sweet clover), Trifolium spp. (true clovers).

Uses

Clovers and alfalfa are small-seeded legumes that fix nitrogen, loosen compacted soil, hold soil against erosion and feed pollinators. Treating seed with the right inoculant improves growth and nitrogen fixation.

Sowing

Sow 1/4–1/2" deep into a firm seedbed at the rates below, using the higher rate when broadcasting. For management they fall into two groups: annuals, and perennials or biennials.

Crimson clover (annual)

Grown as a summer or winter annual depending on the region. In Zone 6 and warmer it is usually sown 6–8 weeks before the first fall frost, overwinters and is terminated in spring. In colder areas, spring sowing gives plenty of biomass and nitrogen by mid- to late summer. It sometimes survives in parts of Zone 5 under good snow cover, so be ready to terminate it in spring there.

Alfalfa

Grown for forage and hay but also useful as a nitrogen-fixing cover. It is slow to start, then grows fast once established. Sow in early spring or late summer, often with a small grain as a nurse crop.

Berseem clover

Drill it, or raise the rate if broadcasting. Spring-sown berseem grows quickly, produces heavy biomass and fixes roughly 100–125 lb. of nitrogen per acre. Sown in late summer in cool climates (Zone 7 and colder), it winter-kills and leaves an easy-to-incorporate cover in spring.

Dutch white clover

Drill or broadcast in early spring or fall, alone or in mixes. It establishes well when frost-seeded into overwintering rye or wheat, or broadcast into standing fall crops, where it grows under the canopy and carries on after the crop is removed. Sow no deeper than 1/4"; the seed is smaller than red clover. White clovers spread readily, so keep seeding rates low.

Red clovers (mammoth and medium)

Sow from early spring to late summer. Both are often frost-seeded into winter grain or oversown into a standing crop at the last cultivation. Both tolerate mowing; medium red clover recovers better.

New Zealand white clover

A good living mulch because it tolerates mowing and foot or vehicle traffic. Sow from early spring to late summer, or frost-seed into winter grain.

Sweet clover

Grows slowly in its first year and produces heavy biomass in the second. Sow from early spring to late summer and terminate before it sets seed: much of its seed is hard and can persist and become weedy.

Seeding rates

Alfalfa: 1/2 lb. per 1,000 sq. ft. or 15–20 lb. per acre (half rate with a grain or grass). Berseem: 1/4–1/3 lb. per 1,000 sq. ft. or 12–15 lb. per acre. Crimson: 1/3–1/2 lb. per 1,000 sq. ft. or 12–20 lb. per acre, alone or with grain or grass. Dutch white: 1/4 lb. per 1,000 sq. ft. or 6–8 lb. per acre. Mammoth and medium red: 1/4–1/2 lb. per 1,000 sq. ft. or 8–12 lb. per acre. New Zealand white: 1/4–1/2 lb. per 1,000 sq. ft. or 5–15 lb. per acre. Sweet clover: 1/4–1/2 lb. per 1,000 sq. ft. or 8–12 lb. per acre. In mixes, halve the clover rate.

Light

Best in full sun, but all tolerate some shade.

Soil

Cool, well-drained soil with a near-neutral pH suits clovers and alfalfa best. Sweet clover copes better with heavy soil and is often used to break up compaction and improve tilth.

Height

See each product description.

Forage

Established stands can be grazed or cut for hay. Alfalfa, New Zealand white clover and medium red clover handle repeated cutting or grazing best.

Termination

Turn clovers and alfalfa under as green manure at any stage; for the most nitrogen, incorporate at flowering. Mowing followed by rototilling, disking or plowing is the usual method, and on a small scale a tarp left on for at least three weeks also works. Second-year sweet clover is tall and stemmy and is hard to handle without larger equipment.

Seeds per lb.

About 247,660 on average.