Fertilising guide

How to fertilise Red Romaine Lettuce (Lactuca sativa var. longifolia 'Rouge d'Hiver')— schedule & NPK

Also called Rouge d'Hiver lettuce, red winter lettuce, red romaine.

More about red romaine lettuce

About Red Romaine Lettuce

Lactuca sativa var. longifolia 'Rouge d'Hiver' · also called Rouge d'Hiver lettuce, red winter lettuce · edible

'Rouge d'Hiver' is a French heirloom red romaine with upright, bronze-red tinged leaves and crisp green hearts. It is unusually cold-hardy for a romaine, making it a reliable autumn, overwintered and early-spring crop. Cool weather and bright light deepen the red colouring; heat and long days fade the colour and push it to bolt and turn bitter.

Growth habit: Annual leafy crop forming an upright, elongated romaine head of self-folding leaves. Bolts into a tall flower stalk under heat and long summer days.

Watch for — Tipburn: Brown, scorched leaf margins come from erratic watering and calcium uptake stress in fast growth or heat. Keep soil evenly moist and avoid moisture swings.

What fertiliser red romaine lettuce actually wants — and why

Red Romaine 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 red romaine 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 red romaine 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 red romaine lettuce:

Feed lightly and steadily. Incorporate compost at planting and, if growth is slow, apply a balanced or nitrogen-leaning liquid feed every 2-3 weeks for fast, tender 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 red romaine 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 red romaine lettuce

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

Signs you are over-feeding red romaine lettuce

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for red romaine 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 red romaine 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 red romaine lettuce care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

For container-grown red romaine 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 red romaine 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 red romaine lettuce — frequently asked questions

What fertiliser does red romaine 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. Red Romaine 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 red romaine lettuce?

Feed lightly and steadily. Incorporate compost at planting and, if growth is slow, apply a balanced or nitrogen-leaning liquid feed every 2-3 weeks for fast, tender leaves. Feed lightly and steadily. Incorporate compost at planting and, if growth is slow, apply a balanced or nitrogen-leaning liquid feed every 2-3 weeks for fast, tender 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 red romaine lettuce?