Black medick

How to recognise it

Growth habit

Annual or short-lived perennial with sprawling to ascending, finely hairy stems of 10–50 cm.

Leaf

Three-parted, the middle leaflet clearly stalked. The leaflets are obovate, 0.5–2 cm, finely toothed towards the tip, with a tiny point in the middle of the tip.

Flower

Dense, rounded heads of 3–8 mm with 10–50 small, bright yellow pea flowers of 2–3 mm, on long stalks from the leaf axils. From May to October.

Fruit/Seed

Small, kidney-shaped pods of 2–3 mm with curved veins, each with one seed. When ripe they are black, so the head looks like a little cluster of black beads.

Roots

Taproot with root nodules, in which bacteria fix nitrogen.

Confused with

Lesser trefoil looks very similar, but its leaflets have no point at the tip, and the withered brown flowers stay around the pods. Hop trefoil has larger, pale yellow heads. Bird’s-foot trefoil has much bigger flowers. Black medick: a point on the leaflet and black, kidney-shaped pods.

Flowering: May–October · Pruning: June and September

Why grow it?

• Honeybees, bumblebees and small wild bees collect nectar and pollen from the yellow heads, from May into October.
• Food plant for the caterpillars of the common blue and of the clouded yellow and pale clouded yellow.
• Fixes nitrogen from the air through nodules on its roots: a pioneer on poor, bare soil and a well-known green manure.
• Flowers low to the ground too, below mowing height: ideal in a flowering lawn.
• The seeds are eaten by finches and other seed-eating birds.

Black medick: where does it grow best?

• In the wild on verges, dykes and embankments, in grassland, lawns, dunes, quarries and on waste or stony ground.
• Full sun; in shade it grows and flowers poorly.
• Dry to moderately moist, well-drained soil, often chalky, sandy or stony; poor to moderately fertile.
• In the garden it suits a flowering lawn, a short wildflower meadow, a gravel garden, path edges or a green manure on an empty vegetable bed.

Goes well with

• Bird’s-foot trefoil: Another yellow legume and the main food plant of the common blue.
• White clover: Together they make a lawn that feeds bees all summer.
• Daisy: Flowers almost all year in the same short lawn.
• Selfheal: Purple flowers low in the grass, also below mowing height.
• Salad burnet: Fine leaves and round heads on the same dry, chalky soil.

Black medick: when and how to plant it?

1. Buy seed of native origin from a nursery or seed supplier for wild plants, on its own or in a flowering-lawn mix.
2. Sow in April–May or in September on loosened, weed-free soil, or in bare patches in your lawn.
3. The seed has a hard coat: rubbing it lightly between sandpaper or soaking it overnight helps germination.
4. Rake the seed in lightly, about 0.5 cm deep, and firm the soil well.
5. Keep the soil moist until the seedlings are up; after that watering is no longer needed.
6. Never dig up plants from the wild: seed works much better and faster.

Care

Water

Only when sowing and for young plants; after that it copes well with drought.

Feeding

Don’t. It takes its own nitrogen from the air, and fertiliser makes the grass so strong that it crowds it out.

Mowing

In a flowering lawn, mow every 3–6 weeks at 5–8 cm; it simply keeps flowering below the mower. In a wildflower meadow, mow in June and September and remove the cuttings.

Spreading

In the vegetable patch or border it can self-seed freely. Pull unwanted plants before the pods turn black.

Letting it seed

Let it set seed in a meadow or edge: that way it stays, even when the old plants die after a year or two.

Tip: For a flowering lawn, mow a bit higher, at 5–8 cm, and stop feeding: black medick, white clover and selfheal often appear by themselves, and the bees follow.

Pruning and mowing

Pruning months: June and September.

When: In a wildflower meadow, mow in June and September; in a lawn, mow every 3–6 weeks.

How:

• Mow at 5–8 cm, so that the low stems and heads stay and quickly flower again.
• At the June cut, leave a strip standing here and there for the bees and caterpillars.
• Remove the cuttings after a few days of drying: this keeps the soil poor and the meadow full of flowers.
• As a green manure, cut it before flowering and work it lightly into the top layer of soil.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

In August–September cut off the black heads, dry them and rub out the seed. Sow in autumn or spring; rubbing the hard seed helps it germinate.

Self-seeding

Let some of the plants drop their seed. It stays viable in the soil for a few years.

Black medick: how does it get through the winter?

Hardy to −25 °C.

• Annual plants die in autumn; short-lived perennial plants overwinter as a low, green plant.
• Autumn seedlings overwinter as a small rosette and flower early the next year.
• Fully hardy; the seed survives the winter in the soil.

Diseases and pests

• Too much in the vegetable patch: On bare soil it likes to self-seed. Weed early, mulch the beds, or keep it as a green manure.
• Disappears in tall grass: It needs short, open vegetation. Mow regularly and don’t feed.
• Pea leaf weevils: Small weevils bite half-moon notches out of the leaf edges. Harmless; leave them be.
• Powdery mildew: A white film on the leaflets in dry late summers. No problem: the plant keeps flowering.

Through the year

• March: Overwintered rosettes start growing.
• April: Sow in bare patches of the lawn or in a wildflower meadow.
• May: First yellow heads.
• June: Flowering. First cut of the wildflower meadow, leaving a strip standing.
• July: Flowering. Look out for the common blue.
• August: Black pods. Collect seed.
• September: Second cut. You can sow.
• October: Last flowers.

Did you know?

• The name lupulina means ‘little hop’: the rounded heads look like tiny hop cones. The Dutch name hopklaver, ‘hop clover’, refers to the same thing.
• The name black medick refers to the pods, which turn black when ripe.
• In Ireland black medick is sometimes sold as shamrock on Saint Patrick’s Day, alongside lesser trefoil and white clover.