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Growing lettuce

Introduction

Lettuce is a cool temperature crop but can be grown all year round in the greenhouse if you choose the correct varieties. Always check the correct sowing time on the packet to ensure success. Some varieties do better in winter and will bolt (go to seed) if sown in the summer and vice-versa.

If selecting lettuce for planting between September and late February select a short day variety, for planting from March to August select a long day variety. 

There are many different types of lettuce available and suited to different uses. Available types include Lollo Rossa, Oak leaf, Cos, Romaine, Butterhead and Loose leaf.

Sowing

  • Seeds can be sown in cell trays and the plants can be transplanted into their final position.
  • Sow indoors in the cooler times of the year and outdoors if weather is very hot in the height of summer. Fill cells evenly with good quality seed and potting compost. Sow one seed per cell and very lightly cover.
  • If using pelleted seeds dib a hole in each cell about 0.5cm deep and drop the pellet in and water well to enable the seed coat to split or break down. Covering is not essential. Keep evenly watered and germination will take place in 4-5 days. If temperatures rise above 20 degrees move seed trays to a cooler spot.

Soil preparation

  • Dig over the soil removing any perennial weed roots.
  • Incorporate well-rotted compost well in advance of planting. Incorporate 50-60 grams of general garden fertiliser into the soil and rake to provide an even bed.

Planting out

  • Transplant into final position when the seedlings have developed 4-5 true leaves and the roots have grown through the compost.
  • Plant lettuce plug plants on the bed surface in winter to prevent the plant sitting in wet conditions which will encourage disease and slightly deeper in summer to ensure it gets sufficient moisture. Plant in rows 20-25cm apart and space 20cm apart in the row.
  • Keep evenly watered.