Description
Lettuce is an annual plant most often grown as a leaf vegetable and used for salads. It comes in a range of varieties with flavors from buttery and mild to nutty and slightly bitter; textures from delicate to crunchy; and colors from pale to dark green and burgundy. Lettuces have a wide range of shapes and textures, from the dense heads of the iceberg type to the notched, scalloped, frilly or ruffly leaves of leaf varieties.
Planting requirements
Planting season: Can be grown year-round in Upcountry Wet and Upcountry Intermediate Zones of Sri Lanka. In lowland areas, best planted during the dry season May to September
Planting conditions:
| Propagation | Seed |
|---|---|
| Planting method | Prepare raised beds about 1 m wide, apply well-decomposed organic manure. Sow seeds in rows at 10 cm spacing in nursery beds. Transplant seedlings after three weeks, spacing plants 30 cm between rows and 15 cm between plants. In upcountry areas, direct seeding is possible |
| Soil | Well-drained sandy loam soil with a loose structure and rich in organic matter. pH should be between 6 and 7 (add lime if soil is too acidic) |
| Water | Water regularly, especially during dry periods. Ensure soil remains moist but not waterlogged |
| Light | In upcountry areas, full sun is acceptable. In lowland areas, partial shade during the hottest part of the day is beneficial |
Growing conditions:
| Temperatures | Optimal growth at less than 20Β°C. In lowland areas, provide shade or grow during cooler months to prevent bolting and bitter taste |
|---|---|
| Soil | Loose, well-draining soil enriched with organic matter. Maintain pH between 6 and 7 |
| Water | Water daily in the first few days after planting. After two weeks, water every four days according to rainfall. In dry zones, more frequent watering may be necessary |
| Pruning | Remove outer leaves as needed for consumption. This promotes continued growth. Remove any yellowing or diseased leaves promptly |
| Weed Control | Maintain proper growth by keeping the field weed-free. Hand weeding is advisable |
Harvesting
Can be harvested 50-60 days after transplanting. At harvest, the entire plant can be removed and the roots cut off. A well-grown plant should weigh about 200 β 400 g. In home gardening, the leaves can be cut separately and used for consumption as required.
Curing
Lettuce does not require a curing stage.
Storage
Store lettuce in a cool, humid place. In areas without refrigeration, wrap in damp cloth and keep in a cool spot. If available, refrigerate at 0Β°C to 4Β°C for up to a week.
Protecting your plants
Pest control
Pest type:
- Root-eating caterpillars
- Cutworms
- Aphids
- Slugs and Snails
Symptoms:
- Root-eating caterpillars: Larvae damage roots and lower stem parts.
- Cutworms: Caterpillars cut seedlings at the base.
- Aphids: Curled or distorted leaves.
- Slugs and Snails: Holes in leaves.
Control method:
- Root-eating caterpillars: Capture adults using yellow or blue sticky traps.
- Cutworms: Inspect crop and apply recommended pesticides for severe damage.
- Aphids: Use neem oil or soap sprays.
- Slugs and Snails: Set up beer traps or use wood ash barriers.
Maintain field hygiene and remove weeds regularly.
Disease Control
Disease type:
- Soft rot
- Sclerotium rot
- Damping off
- Downy mildew
Symptoms:
- Soft rot: Rotting starts from lower leaves and moves upwards.
- Sclerotium rot: White mold growth under humid conditions.
- Damping off: Seedling collapse.
- Downy mildew: Yellowing leaves with white fuzzy growth.
Management:
- Soft rot: Proper spacing and preventing lower leaves from touching the soil. Apply polythene mulch to reduce infection.
- Sclerotium rot: Improve drainage and maintain proper spacing.
- Damping off: Use well-draining soil and avoid overwatering.
- Downy mildew: Ensure good air circulation and avoid overhead watering.
Sources
In addition to our General List of Sources (link), we used these specific references:
- https://www.gardenia.net/guide/best-worst-companions-for-lettuce
- https://www.gardeningknowhow.com/edible/vegetables/lettuce/companion-plants-for-lettuce.htm
- http://farmer.gov.lk/index.php?option=com_content&view=article&id=123&Itemid=76
- https://www.doa.gov.lk/HORDI/index.php/en/crop-recommendations/1103-lettuce
- https://fdc.nal.usda.gov/fdc-app.html#/food-details/169249/nutrients
