Lettuce is one of the world’s favourite salad crops, and something that can be easily grown either from seed or seedlings. There is an amazing range of lettuce, from one-serve meal types such as the butter and mignonette varieties, to ones with ornate and decorative leaves like radicchio, ‘Red Coral’ and oak leaf lettuces. Lettuces with large, firm hearts such as ‘Iceberg’ and cos (sometimes known as ‘Romaine’) store well in the fridge and their large leaves can be pulled off as required.
Lettuce can be purchased either as seed which takes approximately seven days to germinate, or seedlings which mature within six to eight weeks after planting depending on the variety.
Where to plant lettuce
Lettuce is a quick crop which should be consumed when it is still young and tender, and therefore it is important that all its growing requirements are met for best results. Dig the soil well to a depth of 250mm, banging out any clumps with the spade or fork. Spread a generous layer (approximately 2cm) of 5 IN 1 Organic Fertiliser over the top and dig in again. Lettuce are greedy feeders so it’s also a good idea to scatter on some granular fertiliser such as Searles Garden & Vegetable Plant Food to give them a good start. The soil should be worked until it’s fine and loose enough for the shallow roots of the young lettuce plants to establish rapidly. By enriching it with compost the soil is able to retain moisture between applications of water.
Acid soils (those with a pH of less than 6.5) should be neutralised with lime at the suggested application rate, and dug and watered well at least a week prior to planting.
Good drainage, to prevent waterlogging, is essential. Lettuce prefers sun or partial shade, but should be sheltered from excessive wind and summer heat to avoid wilting.
The smaller varieties of lettuce grow superbly well in containers, either companioned with herbs and other small vegetables, or on their own using a ‘combo’ type lettuce seed or seedling mix.
How to plant lettuce
Avoid sowing seed or transplanting seedlings in very hot or windy weather as they are susceptible to high temperatures and desiccation. If you are sowing seed, lightly rake the soil over and make a furrow with the tip of the rake handle.
Planting the seeds in ‘stations’ of a few seeds scattered closely together, with the stations spaced at approximately 30cm apart is helpful; once the seedlings emerge this method facilitates the thinning out process. Cover the row of seeds with a fine layer of sand, seed raising mix or vermiculite. Lettuce seed are very fine so check the packet so ensure you cover them to the correct depth as different plants have different requirements. Water the seed bed well with a fine spray and continue to water regularly until the seedlings are approximately 3cm high and ready to transplant.
The best time to transplant seedlings is after 3pm when the day begins to cool, to allow the plants to recover during the night. Before transplanting your seedlings, water them with a weak solution of liquid seaweed to minimise the shock. Seedlings should be gently removed from the seed bed or punnet and planted individually into a shallow depression, approximately 30cm apart, so just the roots are covered with soil. Again, water well with a fine spray and keep them slightly moist at all times.
Succession planting of your lettuce crops will ensure a constant supply of fresh, tasty leaves.
How to maintain lettuce crop
Ensure that the lettuce bed is free of weeds as they will rob the lettuce of a large percentage of available water and nutrients. Irregular watering will produce bitter leaves. Plants should be watered regularly, especially in hot and windy weather, preferably in the morning to enable the plants to dry out before the cool night air settles.
Lettuce has shallow roots, so a generous layer of mulch (along with regular watering) is important. Keep lettuce crisp and sweet by growing it fast. To do this, make sure it is kept moist and feed it every two weeks with Searles Flourish Tomato & Vegetable Soluble Plant Food (or SeaMax Fish & Kelp, for an organic option).
Pick leaves young and often for a sweeter taste and to promote new leaf growth.
Pests and diseases affecting lettuce
Lettuces are relatively pest and disease free. Fungal infection can be a problem in very humid weather, and should be treated by thinning out the plants to improve air circulation around the remaining lettuces. If aphids appear on any fresh, young growth treat with an organic solution, Ecofend Vegetable & Garden spray. Watch out for chewing pests such as snails and caterpillars. Spray caterpillars and aphids on contact with Searles Bug Beater.