How to Grow Crimson Clovers UK

When to Plant Crimson Clovers in the UK

When to plant crimson clovers in the UK: in Southern England, sow early March to late May. Find your area in the table below.

Region	Sow
Southern England	early March to late May
Midlands	early March to early June
Northern England	mid March to mid June
Scotland	late March to late June

Southern England - detail & sources

PFAF: sow spring to early summer for a nectar/edible-seed crop, or in early autumn as a winter green manure -- taken here as the spring-to-early-summer window for southern England.

Midlands - detail & sources

Sowing window shifted about a week later than southern England for a cooler spring start -- RHS's H4 rating covers Midlands winters fully.

Northern England - detail & sources

Sowing window shifted about two weeks later than southern England for Northern England's cooler spring -- PFAF confirms the species is "not frost tender," so cold itself is not the limiting factor.

Scotland - detail & sources

Sowing window shifted about three weeks later than southern England for Scotland's cooler, later spring -- RHS's H4 rating and PFAF's "not frost tender" note both still apply here.

Quick Facts

Factor	Value
Drainage	Moist but well-drained or well-drained (both sources); PFAF: tolerates light, medium or heavy soils, even nutritionally poor ground.
Lifecycle	RHS: a slender, upright annual or short-lived perennial, rated H4 (-10 to -5°C). PFAF corroborates independently: hardy to UK zone 4 and "not frost tender."
Edible parts	leaves, flowers, seeds

Growth Stages

Stage	BBCH	Notes
Sowing	0	PFAF: pre-soak seed for 12 hours in warm water, then sow in spring to early summer in situ; alternatively, sow in early autumn for use as a winter green manure.
Establishment	3	RHS: generally pest-free and disease-free once established. PFAF: tolerates strong winds but not maritime exposure; fast-growing and weed-suppressing.
Flowering	6	RHS: dense, conical heads of red flowers appear from May to September, providing a good nectar source for bees.
Seed ripening and harvest	8	PFAF: seeds ripen through summer into autumn and can be sprouted for salads or dried and ground into flour; flower heads can also be picked and dried for tea.

Harvest & Storage

When to pick: PFAF: harvest seed once ripe (July-October) for sprouting or grinding, or pick flower heads through the May-September flowering season and dry them for tea.

Storage

PFAF: dry seed can be ground into flour and stored like other cereal/legume flours; dry flower heads for tea, stored airtight out of light.

Crimson Clover, a Fast-Growing Green Manure with Edible Seed

Dense, conical flower heads

RHS: dense, conical heads of red flowers appear in summer, a good nectar source for bees.

Grown as a nitrogen-fixing green manure

RHS: sometimes grown as a nitrogen-fixing cover crop and green manure -- PFAF adds it is fast-growing and effectively weed-suppressing too.

Tolerant of a range of soils

PFAF: succeeds in light, medium or heavy soils, even nutritionally poor ground, provided it gets full sun and reasonably moist conditions.

A genuinely hardy annual

PFAF: hardy to UK zone 4 and "not frost tender" -- RHS separately rates it H4 (-10 to -5°C).

Flowering from May to September

PFAF: in flower from May to September, with seed ripening from July through October.

Used in soil reclamation

PFAF: beyond the garden, crimson clover is used in soil reclamation projects for its fast, weed-suppressing, nitrogen-fixing growth.

Seeds can be sprouted or milled

PFAF: seeds can be sprouted and eaten in salads, or dried and ground into a nutritious flour.

Three-leaflet foliage

RHS: leaves are composed of three leaflets, on a slender, upright annual or short-lived perennial to about 45cm tall.

Dried flowers make a tea substitute

PFAF: dried flower heads are used as a tea substitute, alongside the plant's more familiar role as a cover crop.

What the research guides add

Crimson clover is grown as a cover crop, and SARE’s guide gives the timing rule that matters: sow before the first frost, not after it.

• Seed six to eight weeks before the average date of first frost, at 15 to 18 lb per acre drilled or 22 to 30 lb per acre broadcast. (SARE)
• Planted in late summer it gives good ground cover and weed control as it fixes nitrogen from the air and scavenges nitrogen from the soil; SARE puts its nitrogen contribution at 70 to 150 lb per acre. (SARE)
• It is gaining popularity as a winter-killed annual, like oats, in zones 5 and colder. (SARE)
• Inoculate the seed if crimson clover has not been grown there before. Strongly acidic soil below pH 5.0, or a phosphorus or potassium deficiency, can virtually shut down nitrogen fixation. (SARE)

Sources for this section

• Sustainable Agriculture Research and Education (SARE): Crimson Clover, Managing Cover Crops Profitably

Section researched and checked on 25 October 2026 by the SoilCommander Editorial Team. How we check facts: editorial policy.

References

1. Plants For A Future (PFAF) - Trifolium incarnatum

   Habitat: grassy places, e.g. near the Lizard peninsula in Cornwall; western/southern Europe to the Balkans and Mediterranean. Hardiness: UK zone 4, not frost tender, USDA 3-9. Soil: light/sandy, medium/loamy or heavy/clay, well-drained, can grow in nutritionally poor soil, mildly acid/neutral/basic. Sun: full sun, cannot grow in shade. Moisture: prefers moist soil; tolerates strong winds but not maritime exposure. Size: annual to 0.5m, medium growth rate, in flower May-September. Propagation: pre-soak seed 12 hours in warm water, sow spring to early summer in situ; can also be sown in early autumn as a winter green manure. Edible use: seeds sprouted and eaten in salads, or dried and ground into a nutritious flour; dried flower heads used as a tea substitute. Medicinal use: none known. Other use: fast-growing, weed-suppressing, nitrogen-fixing green manure; used in soil reclamation projects. Safety: no known hazards to people; avoid planting near camellias or gooseberries as it can harbour a mite affecting those plants.

2. Royal Horticultural Society - Trifolium incarnatum (crimson clover)

   Hardiness H4 (-10 to -5°C). Soil: chalk, clay, loam, sand. Position: full sun, east/south/west-facing. Exposure: sheltered. Size: height/spread 0.1-0.5m, 1-2 years to maturity. Moisture: moist but well-drained or well-drained. pH: acid, alkaline or neutral. Propagation: by seed. Pests: generally pest-free. Diseases: generally disease-free. Description: slender, upright annual or short-lived perennial to 45cm, leaves of three leaflets, dense conical heads of red flowers in summer, good nectar source for bees; sometimes grown as a nitrogen-fixing cover crop and green manure.

2 independent sources are cited for this crop. Where they disagree - soil pH is the clearest case - every figure is preserved rather than averaged into false precision.