Fertilising guide
How to fertilise Black Medick (Medicago lupulina)— schedule & NPK
Also called Black Medick, Black Medic, Hop Clover, Nonesuch, Yellow Trefoil.
More about black medick
About Black Medick
Medicago lupulina · also called Black Medick, Black Medic · flowering
Medicago lupulina is a low-growing annual or short-lived perennial legume native to grasslands, roadsides, and disturbed ground across Europe, Asia, and northern Africa, widely naturalised in North America and Australasia. It thrives in full sun on poor to moderately fertile, well-drained soils and, as a legume, fixes atmospheric nitrogen through root nodules — so avoid nitrogen-rich fertilisers. The tiny yellow clover-like flowers turn into distinctive black coiled seed pods that give the plant its common name. It is not considered toxic to cats or dogs.
Growth habit: Low-growing, spreading annual or short-lived perennial with trifoliate leaves and prostrate to ascending stems.
What fertiliser black medick actually wants — and why
Black Medick is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for black medick: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed black medick, and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For black medick:
Do not fertilise — this nitrogen-fixing legume performs best on poor soils; added nitrogen suppresses nodule activity and encourages weedy competition. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
The dormant-season rule matters more than the exact interval: skip feeding entirely when black medick is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for black medick
Half strength is the safe default for black medick — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
Feeding always goes onto already-damp soil, never dry roots — water black medick first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the black medick watering schedule.
Signs you are over-feeding black medick
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for black medick:
- Brown, crispy leaf tips and edges with no sign of underwatering.
- A white, crusty salt deposit on the soil surface or pot rim.
- Weak, pale, stretched new growth that flops.
- Lower leaves yellow and drop while the soil is correctly watered.
Signs you are under-feeding black medick
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full black medick care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of black medick with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Organic vs synthetic feeds for black medick
Organic options
A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.
Synthetic / liquid feeds
A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising black medick — frequently asked questions
What fertiliser does black medick need?
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Black Medick is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
How often should I feed black medick?
Do not fertilise — this nitrogen-fixing legume performs best on poor soils; added nitrogen suppresses nodule activity and encourages weedy competition. Do not fertilise — this nitrogen-fixing legume performs best on poor soils; added nitrogen suppresses nodule activity and encourages weedy competition. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
What strength of feed for black medick?
Half strength is the safe default for black medick — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding black medick look like?
Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding black medick year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.
Should I flush the soil of black medick?
Flush the pot of black medick with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Keep reading
- Black Medick care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water black medick — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise eryngium giganteum 'silver ghost'
- How to fertilise helenium 'rotgold'
- How to fertilise helenium autumnale 'pumilum magnificum'
- All 10153 fertilising guides in the Growli library