Fertilising guide

How to fertilise Sea Rocket (Cakile maritima)— schedule & NPK

Also called Sea rocket, European sea rocket, European searocket.

More about sea rocket

About Sea Rocket

Cakile maritima · also called Sea rocket, European sea rocket · edible

Cakile maritima is a fleshy-leaved annual or biennial native to Atlantic and Mediterranean coastlines, where it colonises open sandy beaches and strandlines in full sun. It is a classic halophyte — salt-tolerant and adapted to nutrient-poor, shifting sand — and demands excellent drainage above all else. Its young leaves, flowers, and seed pods are edible raw or cooked with a pungent, peppery, mustard-like flavour similar to horseradish. It is considered non-toxic to pets.

Growth habit: Sprawling, branched annual or biennial with fleshy, pinnately lobed leaves and distinctive two-jointed seed pods.

What fertiliser sea rocket actually wants — and why

Sea Rocket 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 sea rocket: 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 sea rocket, 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 sea rocket:

Little to none required — feed very lightly with a balanced fertiliser once in the growing season; excess nitrogen promotes soft, pest-prone growth with reduced flavour in the leaves. 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 sea rocket 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 sea rocket

Use the vegetable-feed label rate for sea rocket. 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 sea rocket first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the sea rocket watering schedule.

Signs you are over-feeding sea rocket

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

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 sea rocket

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 sea rocket care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

For container-grown sea rocket, 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 sea rocket

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 sea rocket — frequently asked questions

What fertiliser does sea rocket 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. Sea Rocket 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 sea rocket?

Little to none required — feed very lightly with a balanced fertiliser once in the growing season; excess nitrogen promotes soft, pest-prone growth with reduced flavour in the leaves. Little to none required — feed very lightly with a balanced fertiliser once in the growing season; excess nitrogen promotes soft, pest-prone growth with reduced flavour in the leaves. 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 sea rocket?