Lucerne

How to recognise it

Growth habit

Perennial, upright to ascending, much-branched plant of 30–90 cm, from a woody base.

Leaf

Three-parted, with oblong leaflets of 1–3 cm that are toothed only at the tip.

Flower

Pea flowers of 7–11 mm in short, dense clusters, purple, violet or bluish. From June to September.

Fruit/Seed

Pods 4–6 mm across, coiled two to three times in a spiral, slightly hairy, with a few kidney-shaped seeds.

Roots

A very deep taproot that can reach several metres down, with root nodules in which bacteria fix nitrogen.

Confused with

Sickle medick has yellow flowers and sickle-shaped pods; sand lucerne, the hybrid of the two, has flowers in changing colours from yellow and green to purple. Tufted vetch also has violet flowers, but pinnate leaves with tendrils. Melilots have long, airy spikes of small white or yellow flowers.

Flowering: June–September · Pruning: March and July

Why grow it?

• Bumblebees, honeybees and many wild bees visit the flowers from June to September.
• Food plant for the caterpillars of the pale clouded yellow, the clouded yellow and the common blue.
• Fixes nitrogen and loosens heavy soil with its deep roots: an excellent green manure for the vegetable garden.
• Copes very well with drought and stays green when the grass has already turned brown.
• Sprouted seeds are eaten in salads as ‘alfalfa’; only use seed sold specifically for sprouting.

Lucerne: where does it grow best?

• In the wild on verges, dykes, railway embankments, field edges, waste ground and in chalk grassland.
• Full sun; in shade it flowers little.
• Dry to moderately moist, deep and well-drained soil, chalky to neutral. It does poorly on wet, acid soil.
• In the garden: in a sunny wildflower meadow, a bee border, on a bank or as a green manure in the vegetable patch.

Goes well with

• Chicory: Sky-blue flowers on the same dry, chalky soil.
• Common knapweed: Purple heads, and also excellent for bees and butterflies.
• Wild carrot: White umbels next to the purple clusters on a sunny bank.
• Ribbed melilot: Yellow spikes and the same kind of soil; together they draw lots of bees.
• Oxeye daisy: White flowers in the same wildflower meadow.

Lucerne: when and how to plant it?

1. Buy untreated seed from a seed supplier, as a green manure or as seed for a wildflower meadow.
2. Sow from April to August on a fine, weed-free seedbed, about 1 cm deep, broadcast or in rows 20–30 cm apart.
3. Firm the soil and keep it moist until the seed has germinated, usually within one to two weeks.
4. If you choose pot-grown plants, plant them 30–40 cm apart and plant them out young: older plants with a long taproot transplant badly.
5. Choose the spot carefully: because of the deep root, a mature plant is hard to get rid of.
6. Never dig up plants from the wild: seed works much better.

Care

Water

Only when sowing and in the first spring. After that it manages even in dry summers.

Feeding

Not needed: it takes its own nitrogen from the air. Fertiliser makes the stems floppy.

Mowing

For bees, let it flower and cut back half in July for a second flush. As a green manure, cut before flowering, two to four times a year.

Green manure

Leave it on an empty bed for one or two years; cut it and leave the cuttings as a mulch or work them in lightly.

Space

After a few years it forms sturdy clumps. Give it 40–50 cm.

Tip: Sow lucerne as a green manure on an empty vegetable bed and let a strip flower: your soil gains nitrogen and structure, and the bumblebees get a feast.

Pruning and mowing

Pruning months: March and July.

When: In March clear the old stems; in July, after the first flowering, cut back half of the stems.

How:

• Leave the dead stems standing over winter: small insects overwinter in them.
• In March cut or mow them down to just above the ground, before the new shoots grow.
• In July cut half of the stems back to 10 cm: they flower again in August–September, while the rest feeds the bees.
• In late summer let some set seed if you want it to self-sow.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Sow from April to August. Collect ripe seed in September from the brown, coiled pods.

Self-seeding

In a wildflower meadow it self-seeds moderately; seedlings can be moved while young.

Lucerne: how does it get through the winter?

Hardy to −30 °C.

• The stems die back; the plant overwinters with a woody base and buds at ground level.
• Very hardy, to about −30 °C, thanks to its deep root.
• The dry stems shelter small insects; the new shoots appear in March.

Diseases and pests

• Weevils: Small weevils bite notches out of the leaf edges. Harmless to the plant; leave them be.
• Root rot: On wet, heavy soil the roots rot. Choose a well-drained spot.
• Slow start: On soil where lucerne has never grown, the right root bacteria may be missing, so it grows slowly. After a year things usually improve.
• Hard to remove: The taproot goes deep. Dig out young plants; old plants need serious digging.

Through the year

• March: Cut off old stems. New shoots appear.
• April: Sow on a fine seedbed in the sun.
• May: Cut green manure before flowering.
• June: First purple flowers. Bumblebees on the clusters.
• July: Full flowering. Cut back half of the stems.
• August: Second flowering. Look out for clouded yellows.
• September: Last flowers. Collect seed from the coiled pods.
• November: Leave dead stems for the insects.

Did you know?

• The name Medicago refers to Media, in ancient Persia: the Greeks came to know the plant from there.
• The word alfalfa comes from Arabic, via Spanish. For lucerne, the usual explanation is a Provençal word for glow-worm, after the shiny seeds.
• Honeybees often learn to take nectar from the side of the flower without triggering its mechanism. For seed production, leafcutter bees are therefore also used.