Salad Crops - Lettuce
Introduction
For most of us lettuce is probably the most familiar salad plant. It is a fairly hardy, cool-weather vegetable that thrives when the average daily temperature is between 60 and 70°F.
Lettuces generally like to grow in partial to full shade.
There are five types of lettuce;
- Leaf - Leaf lettuce, the most widely adapted type, produces crisp leaves loosely arranged on the stalk.
- Cos / Romaine - forms an upright, elongated head
- Crisphead - the iceberg types common at supermarkets all over the country, are adapted to northern conditions and require the most care
- Butterhead - generally small, loose-heading types that have tender, soft leaves with a delicate sweet flavor.
- Stem - forms an enlarged seedstalk that is used mainly in stewed, creamed and Chinese dishes.
The main distinction is between the heading or hearting lettuces (butterheads, cos, romaine and crisphead) and the loose leaf kinds. One thing they have in common is that they all require consistently moist conditions.
Soil
Lettuce likes a partly sunny to shady spot and the soil needs to contain plenty of organic matter - more to retain moisture than for it's nutritional value.
For summer lettuce dig in compost during the winter, rake to a fine tilth before sowing, incorportaing 1 oz per square yard (33g/sq m) of compound fertiliser. Winter lettuce should succeed runner beans or potatoes without additional manuring.
When to Sow
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sow | ||||||||||||
| Harvest |
For an outdoor spring crop, sow in September. For a cloche spring crop sow in early October and cloche immediately.
For crops from June to October, sow at 3 weekly intervals from late March to early July.
Sowing
Sow in drills about 1/2 in (1.25cm) deep and 12 inches (30cms) apart. Bring the soil to a fine tilth, water the drills before sowing in dry weather and firm the surface after sowing. Sow thinly and protect from birds.
Time to Germination
7 - 14 days
Season of Use
Autumn sown: April - June harvested.
Spring and Summer sown: June to October harvested.
Caring for the Crop
Do not thin autumn-sown crops until the spring.
Thin all sowings to a final distance of 9-12 inches (22-30cms) for most varieties but 6-8 inches (15-20cms) for Little Gem and Tom Thumb.
Lettuce does not need a lot of water but it does need to be continuously moist. It is important to make sure your lettuce bed does not dry out as this will cause the lettuce to bolt and become bitter. Growing lettuce in a semi-shaded to shaded location and using a straw mulch around the plants helps retain moisture. When watering concentrate the water at the base of the plant, not on the leaves. Watering the leaves encourages diseases and may damage some varieties of the more delicate lettuces.
Harvesting
Lettuce grows quickly and is ready before flowers appear. The trick to harvesting lettuce is picking it before it is bitter. If flowering stalks appears, the plant is past its prime. Lettuce can be harvested as soon as true leaves appear but let the lettuce plants develop enough so that harvesting 3-4 leaves from the outside of the rosette of each plant will not harm the plant's growth. If you are harvesting the whole lettuce head, wait until it is bigger than the size of your fist and harvest the lettuce before it becomes bitter. If in doubt, try a leaf!
Harvest either the largest, outside leaves or the whole plant. If harvesting tender young lettuce that is tightly spaced use a pair of scissors to cut the lettuce above the soil line.
Lettuce can be started indoors for early planting in the spring or for succession planting. Start lettuce seeds in trays with individual cells. Be careful not to cover the seeds with soil, gently pressing the seeds into the moist starting mix is enough to ensure good germination. For best results, start seeds one month before planting out.
