Fertilising guide

How to fertilise Cabbage (Brassica oleracea var. capitata)— schedule & NPK

Also called summer cabbage, autumn cabbage, savoy cabbage.

About Cabbage

Brassica oleracea var. capitata · also called summer cabbage, autumn cabbage · edible

Cabbage is a cool-season brassica grown for dense leafy heads. Successional varieties cover spring, summer, autumn, and winter slots. Heavy feeders that suffer the same pest pressure as kale and broccoli. Toxic to pets in large amounts.

Cabbage is the heading (Capitata Group) form of Brassica oleracea, selected from wild Mediterranean cabbage for tightly overlapping leaves that curve inward to form a dense head.

A heavy nitrogen feeder; nitrogen is typically split between transplanting and the start of heading to size up firm heads.

Growth habit: Biennial grown as an annual

Sources: hgic.clemson.edu, plants.ces.ncsu.edu, pmc.ncbi.nlm.nih.gov

What fertiliser cabbage actually wants — and why

Cabbage is grown entirely for its leaves, so nitrogen is the priority — steady, nitrogen-leaning feeding keeps it growing fast, tender and unbolted.

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 cabbage: 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 cabbage, 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 cabbage:

A balanced feed at planting; nitrogen side-dressing once heads start forming. In practice: a balanced or compost-rich start, then a nitrogen side-dress or liquid feed every 3-4 weeks through the cropping period in the main season (spring through early autumn).

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

Use the vegetable-feed label rate for cabbage. Steady availability matters more than a strong dose — a check in growth makes leaves tough and can trigger bolting.

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

Signs you are over-feeding cabbage

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

Very soft, floppy, dark-green growth that attracts aphids.
Excess leafy growth at the expense of hearts/heads in cabbage and the like.
Salt crust and scorched leaf edges in containers; nitrate-heavy leaves.

Signs you are under-feeding cabbage

Pale, yellow-green leaves, oldest first, and slow growth.
Small, tough, bitter leaves and premature bolting.
Weak, stunted heads in cabbage, broccoli and cauliflower.

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

Flushing and leaching the salts

For container-grown cabbage, water until it drains freely each time and flush pots monthly with plain water to stop nitrogen salts accumulating; in the ground, good compost levels naturally buffer this.

Organic vs synthetic feeds for cabbage

Organic options

Well-rotted manure or compost dug in, plus nitrogen-rich liquid feeds like diluted chicken-manure pellets or nettle feed. UK: pelleted chicken manure or Westland; US: Espoma Garden-tone or blood meal. Steady and soil-building.

Synthetic / liquid feeds

A balanced feed at planting then a high-nitrogen liquid or granular side-dress — UK: Growmore then a nitrogen feed or Phostrogen; US: a 10-10-10 then a high-N (e.g. 21-0-0) side-dress or Miracle-Gro.

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 cabbage — frequently asked questions

What fertiliser does cabbage need?

A nitrogen-leaning feed (higher first number) or compost-rich soil — nitrogen drives the fast, tender leafy growth this crop is grown for. Phosphorus and potassium matter far less here than for fruiting crops. Cabbage is grown entirely for its leaves, so nitrogen is the priority — steady, nitrogen-leaning feeding keeps it growing fast, tender and unbolted.

How often should I feed cabbage?

A balanced feed at planting; nitrogen side-dressing once heads start forming. A balanced feed at planting; nitrogen side-dressing once heads start forming. In practice: a balanced or compost-rich start, then a nitrogen side-dress or liquid feed every 3-4 weeks through the cropping period in the main season (spring through early autumn).

What strength of feed for cabbage?