Fertilising guide

How to fertilise Kidney Vetch (Anthyllis vulneraria)— schedule & NPK

Also called Kidney Vetch, Lady's Fingers, Woundwort.

More about kidney vetch

About Kidney Vetch

Anthyllis vulneraria · also called Kidney Vetch, Lady's Fingers · flowering

Anthyllis vulneraria is a low-growing perennial or biennial legume native to calcareous grasslands, cliffs, and coastal dunes across Europe, North Africa, and western Asia. It bears dense, woolly heads of yellow, orange, or red flowers from June to September and fixes atmospheric nitrogen through root nodule bacteria. The most important care fact is excellent drainage on infertile, alkaline soil: rich or waterlogged conditions cause rapid decline. The plant is not known to be toxic to pets.

Growth habit: Low-growing, spreading perennial or biennial with pinnate, silky-hairy leaves forming loose mats; erect flower stems produced in summer.

What fertiliser kidney vetch actually wants — and why

Kidney Vetch flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.

Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency.

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 kidney vetch: 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 kidney vetch, 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 kidney vetch:

Do not fertilise; as a nitrogen-fixing legume it thrives in nutrient-poor conditions and feeding promotes weak, leafy growth at the expense of flowers. In practice: no routine feeding at all for kidney vetch — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.

The dormant-season rule matters more than the exact interval: skip feeding entirely when kidney vetch 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 kidney vetch

None is the correct answer for kidney vetch. The flower-versus-foliage trade-off is the whole point: hold back and you get the display.

Feeding always goes onto already-damp soil, never dry roots — water kidney vetch first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the kidney vetch watering schedule.

Signs you are over-feeding kidney vetch

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for kidney vetch:

Abundant leafy growth and very few flowers (the classic over-rich symptom).
Soft, floppy stems and a sprawling, leafy habit.
Scorched edges and salt crust if it has been fed in a container.

Signs you are under-feeding kidney vetch

Effectively never an issue — these plants flower on poverty.
Only on genuinely dead soil: weak, thin growth and few blooms.
A short-lived plant in completely spent container compost.

If the symptoms point at watering, light or roots rather than nutrition, the full kidney vetch care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

If kidney vetch has accidentally been fed and is all leaf, a plain-water flush plus a move to leaner soil resets it; otherwise no flushing is needed because you are not feeding it.

Organic vs synthetic feeds for kidney vetch

Organic options

A thin compost mulch for soil structure is the absolute most; mostly, give it nothing. UK/US: leave it lean — no manure, no liquid feed. Poor soil is the active ingredient here.

Synthetic / liquid feeds

None. Synthetic feeds, particularly anything with appreciable nitrogen, directly suppress flowering in kidney vetch.

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 kidney vetch — frequently asked questions

What fertiliser does kidney vetch need?

Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency. Kidney Vetch flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.

How often should I feed kidney vetch?

Do not fertilise; as a nitrogen-fixing legume it thrives in nutrient-poor conditions and feeding promotes weak, leafy growth at the expense of flowers. Do not fertilise; as a nitrogen-fixing legume it thrives in nutrient-poor conditions and feeding promotes weak, leafy growth at the expense of flowers. In practice: no routine feeding at all for kidney vetch — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.

What strength of feed for kidney vetch?