Fertilising guide

How to fertilise Butterhead Lettuce (Lactuca sativa var. capitata 'Butterhead')— schedule & NPK

Also called butterhead lettuce, butter lettuce, Boston lettuce.

More about butterhead lettuce

About Butterhead Lettuce

Lactuca sativa var. capitata 'Butterhead' · also called butterhead lettuce, butter lettuce · edible

Butterhead lettuce forms a loose, rounded head of soft, buttery leaves with a mild, sweet flavour. A cool-season crop, it matures in about 45-65 days and is quick and forgiving for beginners. Sow in succession from spring to late summer for continuous picking, and shade in midsummer to prevent bolting.

Growth habit: Low, rosette-forming annual that develops a soft, loose head; bolts upward into a flower stalk once stressed by heat or long days.

Watch for — Tip burn: Brown, scorched leaf margins from calcium not reaching fast-growing tissue, usually due to uneven moisture or heat. Keep watering consistent and avoid heat stress.

What fertiliser butterhead lettuce actually wants — and why

Butterhead Lettuce 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 butterhead lettuce: 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 butterhead lettuce, 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 butterhead lettuce:

Usually needs little feeding in fertile soil. A light balanced or nitrogen-leaning feed early on supports leafy growth; avoid overfeeding, which produces soft, disease-prone 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 butterhead lettuce 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 butterhead lettuce

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

Signs you are over-feeding butterhead lettuce

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

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 butterhead lettuce

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 butterhead lettuce care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

For container-grown butterhead lettuce, 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 butterhead lettuce

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 butterhead lettuce — frequently asked questions

What fertiliser does butterhead lettuce 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. Butterhead Lettuce 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 butterhead lettuce?

Usually needs little feeding in fertile soil. A light balanced or nitrogen-leaning feed early on supports leafy growth; avoid overfeeding, which produces soft, disease-prone leaves. Usually needs little feeding in fertile soil. A light balanced or nitrogen-leaning feed early on supports leafy growth; avoid overfeeding, which produces soft, disease-prone 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 butterhead lettuce?