How Many Days Is the Lettuce Growing Cycle? A Detailed Explanation from Sowing to Harvest

The growing cycle of head lettuce is 100-120 days, and the growing cycle of non-heading lettuce is 60-90 days. For non-heading lettuce, when seedlings are raised and transplanted in spring and autumn, the seedling stage is about 25 days, and harvest is about 35 days after transplanting; when direct-sown in summer, harvest can be done about 35 days after sowing; when seedlings are raised and transplanted in winter, the seedling stage is about 30 days, and harvest is about 50 days after transplanting.

The growth stages of the lettuce growing cycle

Lettuce goes through 4 stages, namely the germination stage, seedling stage, rosette stage, and heading stage.

1. Germination stage: from seed swelling to the unfolding of the cotyledons, it takes about 8-10 days. The minimum temperature for lettuce seed germination is 4°C, and the optimum temperature for germination is 15-20°C. Below 15°C, germination uniformity is poor; above 25°C, the germination rate drops significantly because the seed coat impedes water uptake; above 30°C, germination is hindered.

2. Seedling stage: from the appearance of true leaves to the unfolding of the 5th leaf of the 1st leaf order, commonly known as “forming a rosette”, it takes about 20-25 days, and the optimum growing temperature is 16-20°C.

3. Rosette stage: from the formation of the rosette to the completion of the 2nd leaf order, when the heart leaves begin to curl inward, it takes about 15-30 days, and the optimum growing temperature is 18-22°C. During this period the leaf area expands rapidly, and it is the key period for the formation of the marketable organ.

4. Heading stage: the heart leaves rapidly curl inward to form a plump head, taking about 35-40 days.