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Lettuce

Crop profile

Lettuce crop profile

A versatile, quick leafy crop, suited to repeated sowing or transplanting for tender heads over time.

Italiano

Starting method

Direct sowing or transplanting

Direct soil

2 °C

Transplant soil

2 °C

Night minimum

2 °C

Frost buffer

-10 days

Heat stop

28 °C

Harvest

35–60 days

Indoor lead

28 days

Key temperatures

  1. 0
  2. 5
  3. 10
  4. 15
  5. 20
  6. 25
  7. 30
  8. 35
  9. 40 °C
  • Below 2 °CCold risk: slower growth or cold damage.
  • 2 °CMinimum range to start: direct sowing from 2 °C, transplanting from 2 °C.
  • 2–23 °CBest range for growth and production.
  • 23–28 °CPerformance drops and plants move into stress.
  • Above 28 °CPause transplants: heat stress risk.

Lettuce cycle

  1. 1. Start indoors

    Average time:
    28 days

  2. 2. Direct sowing or transplanting

    Soil: at least 2 °C
    Night minimum: at least 2 °C

  3. 3. Growth

    Ideal temperatures 2–23 °C
    Avoid peaks above 28 °C

  4. 4. Harvest

    First harvest around:
    35–60 days after starting

How to start

  • Recommended method: direct sowing or transplanting.
  • Prepare seedlings with mild, steady temperatures.
  • Start when soil and nights are stable above the crop thresholds.

Temperatures to respect

  • Direct-sowing soil: minimum 2 °C.
  • Transplant soil: minimum 2 °C.
  • Night minimum: minimum 2 °C.
  • Heat stop: 28 °C.
  • Suggested frost buffer: -10 days.

Harvest timing

  • Cycle to first harvest: about 35–60 days.
  • Harvest gradually as produce reaches maturity.

Seasonal notes

  • Protect young plants from late frosts and thermal swings.
  • In summer, avoid water stress and heat peaks above 28 °C.
  • Steady growth improves development and harvest quality.

FAQ and sources

When should you sow lettuce?

Lettuce is a cool-season crop and can be sown early: the parameters indicate soil and nights around 2 °C, with a slight margin before the final frost. It grows well in spring and autumn, while peak summer needs heat-tolerant varieties and light shade. You can direct sow or transplant young plants, including seedlings started about 28 days earlier. For continuous harvests, sow small amounts every two weeks instead of one large bed.

Is head lettuce or cut-and-come-again lettuce better?

It depends on use. Head lettuce makes larger, neater heads, but it needs more space and a longer cycle. Cut-and-come-again lettuce is faster and practical for balconies, mixed beds, and frequent harvests: you cut outer or young leaves and let the plant regrow. For continuity, grow both. Harvest usually comes in 35-60 days, but baby leaves can be cut earlier. Keep the soil cool: tender leaves and fast growth depend on water.

Why does lettuce bolt and turn bitter?

Lettuce bolts when it faces heat, drought, long days, or root stress. The practical heat limit is around 28 °C: above this, many varieties speed up flowering and the leaves become bitter. In summer, sow in partial shade, choose summer varieties, water often, and harvest young. Do not leave plants too crowded: they compete for water and light and stress earlier. In strong heat, pause sowing or switch to quick baby leaf crops.

Can lettuce be grown in pots?

Yes. Lettuce is excellent in pots because it has shallow roots and a short cycle. Use containers that are wide rather than deep, with fertile, free-draining compost. Cut-and-come-again types are the easiest: sow fairly close, but not too dense, then harvest gradually. In summer, move the pot where it gets morning sun and shade in the hottest hours. Water is the key point: pots dry fast, and stressed lettuce becomes tough, bitter, and more likely to bolt.

Can lettuce be grown in autumn?

Yes. Lettuce has a good autumn window. With milder temperatures it grows more slowly, but leaves are often sweeter and crisper than in summer. Choose cold-suitable varieties, sow early enough for seedlings to start before the shortest days, and use fleece or a low tunnel in cold areas. In autumn, avoid waterlogging: low light and wet soil encourage rots. Harvest during dry hours and leave space between plants for air movement.

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