Lettuce – How to Plant, Care & Pests

Lettuce is one of the most popular and versatile vegetables you can grow in your garden or container. It’s easy to start from seed, grows quickly, and can be harvested throughout the season. Plus, it comes in many different shapes, colors, and flavors, from crunchy iceberg to tender butterhead. Whether you want to make a salad, a sandwich, or a wrap, lettuce is a great ingredient to have on hand.

In this article, we’ll show you how to plant lettuce in your garden or container, and how to care for it until it’s ready to harvest. We’ll also give you some tips on how to choose the best variety for your climate and taste, and how to prevent common problems and pests.

Choosing a Lettuce Variety

There are four main types of lettuce: head, leaf, romaine, and stem. Each type has its own characteristics and preferences, so it’s important to choose the one that suits your needs and preferences.

• Head lettuce forms a tight ball of leaves, like a cabbage. It takes longer to mature than other types, and needs more space and water. It’s also more sensitive to heat and cold, and may bolt (flower and turn bitter) or rot in extreme temperatures. Iceberg and bibb are examples of head lettuce. Click here for more info.

• Leaf lettuce has loose, curly, or frilly leaves that grow in a rosette. It matures faster than head lettuce, and can be harvested leaf by leaf or cut as a whole. It’s more tolerant of heat and cold, and can be grown in small spaces and containers. It’s also more diverse in color and flavor, from green to red, and from mild to spicy. Oakleaf and lollo rosso are examples of leaf lettuce.

• Romaine lettuce has long, upright, and crisp leaves that form a loose head. It’s slower to mature than leaf lettuce, but faster than head lettuce. It needs more space and water than leaf lettuce, but less than head lettuce. It’s more resistant to bolting and rotting than head lettuce, and has a sweet and nutty flavor. Cos and little gem are examples of romaine lettuce.

• Stem lettuce has thick and edible stems that are harvested before the leaves form. It’s also known as asparagus lettuce or celtuce. It matures faster than other types, and can be grown in small spaces and containers. It’s more tolerant of heat and cold than other types, and has a mild and slightly bitter flavor. The stems can be peeled and eaten raw or cooked, and the leaves can be used like other lettuces.

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Sowing Lettuce Seeds

Lettuce is a cool-season crop that grows best in temperatures between 45°F and 75°F (7°C and 18°C). You can sow lettuce seeds directly in the ground or in containers, or start them indoors and transplant them later.

• Direct sowing is the easiest and most common method of planting lettuce. You can sow lettuce seeds in the ground as soon as the soil can be worked in spring, or in late summer or early fall for a fall or winter crop. Sow the seeds 1/8 to 1/4 of an inch deep, and 1 to 2 inches apart, in rows 12 to 15 inches apart. You can also scatter the seeds in a wide row or bed, and thin them later. Keep the soil moist and weed-free until the seeds germinate, which usually takes 7 to 10 days.

• Starting indoors is a good option if you want to get a head start on the season, or if you have limited space or poor soil. You can start lettuce seeds indoors about 4 to 6 weeks before the last spring frost, or 6 to 8 weeks before the first fall frost. Use seed trays or pots filled with a soilless growing medium, and sow the seeds lightly on the surface. Keep the trays or pots in a sunny window or under grow lights, and keep the medium moist but not soggy. The seeds should sprout in 3 to 5 days.

• Transplanting is the next step if you start your lettuce seeds indoors. You can transplant your lettuce seedlings into the garden or containers when they have 3 to 4 true leaves, and when the outdoor temperature is above 40°F (4°C). Harden off the seedlings for a week by exposing them to the outdoor conditions gradually, starting with a few hours a day. Then, plant them 6 to 12 inches apart, depending on the variety, in rows 12 to 15 inches apart. Water them well and protect them from frost if necessary.

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Caring for Lettuce Plants

Lettuce is a low-maintenance crop that doesn’t need much attention once it’s established. However, there are a few things you can do to ensure a healthy and productive harvest.

Watering 

Watering is essential for lettuce, as it’s mostly made of water and has shallow roots. Water your lettuce plants regularly and deeply, especially during hot and dry weather. The soil should be moist but not waterlogged, as too much water can cause root rot and fungal diseases. A drip irrigation system or a soaker hose is ideal for watering lettuce, as it delivers water directly to the roots and prevents wetting the leaves, which can encourage diseases and pests.

Fertilizing 

Fertilizing is optional for lettuce, as it doesn’t need much nutrients to grow. However, if you want to boost the growth and quality of your lettuce, you can apply a balanced organic fertilizer, such as compost, fish emulsion, or seaweed extract, every 2 to 4 weeks. Avoid high-nitrogen fertilizers, as they can cause excessive leaf growth and reduce the flavor and crispness of the lettuce.

Mulching 

Mulching is beneficial for lettuce, as it helps retain soil moisture, suppress weeds, and moderate soil temperature. You can use organic materials, such as straw, grass clippings, or shredded leaves, to mulch around your lettuce plants, leaving a few inches of space around the stems. Mulch also helps prevent soil splash, which can spread diseases and pests to the lettuce leaves.

Thinning 

Thinning is necessary for lettuce, as it allows the plants to have enough space and air circulation to grow. You can thin your lettuce plants by removing the weakest or smallest seedlings, or by cutting them at the soil level with scissors. You can thin your lettuce plants several times, until they reach the final spacing of 6 to 12 inches apart, depending on the variety. You can eat the thinned seedlings as baby greens, or add them to salads or sandwiches.

Harvesting 

Harvesting is the most rewarding part of growing lettuce, as you get to enjoy fresh and crisp lettuce from your own garden or container. You can harvest lettuce in different ways, depending on the type and your preference.

• Leaf by leaf harvesting is suitable for leaf and romaine lettuce, as they produce new leaves from the center of the plant. You can harvest individual leaves from the outer part of the plant, leaving the inner part intact. This way, you can extend the harvest period and enjoy fresh lettuce for several weeks.

• Cut and come again harvesting is another option for leaf and romaine lettuce, as well as for head lettuce that hasn’t formed a tight head yet. You can harvest the whole plant by cutting it about an inch above the soil level, leaving the roots and the base of the stem in the ground. The plant will regrow new leaves from the base, and you can harvest it again in a few weeks.

• Head harvesting is the final option for head and romaine lettuce, as well as for leaf lettuce that has grown too large or started to bolt. You can harvest the whole head by cutting it at the soil level, or by pulling it out with the roots. You can store the head in the refrigerator for up to a week, or eat it right away.

Preventing Problems and Pests

Lettuce is generally a trouble-free crop, but it can sometimes encounter some problems and pests that can affect its growth and quality. Here are some common issues and how to prevent or treat them.

• Bolting is the term for when lettuce plants start to flower and produce seeds, which makes the leaves bitter and tough. Bolting is triggered by high temperatures, long days, or stress. To prevent bolting, choose heat-tolerant or slow-bolting varieties, sow lettuce seeds in succession, provide adequate water and mulch, and harvest lettuce regularly. If your lettuce plants start to bolt, you can either harvest them as soon as possible, or let them flower and collect the seeds for next season.

• Tipburn is the term for when the edges of the lettuce leaves turn brown and dry, which reduces the quality and appearance of the lettuce. Tipburn is caused by calcium deficiency, which is often related to uneven water supply or high humidity. To prevent tipburn, provide consistent water and good drainage, avoid overhead watering, and use calcium-rich fertilizers or amendments, such as lime or gypsum.

• Rotting is the term for when the lettuce plants develop soft and mushy spots, which can affect the roots, stems, or leaves. Rotting is caused by fungal or bacterial diseases, such as damping-off, bottom rot, or soft rot. To prevent rotting, use disease-resistant varieties, practice crop rotation, avoid planting lettuce in wet or poorly drained soil, and remove and destroy infected plants.

• Slugs and snails are the most common pests that attack lettuce, as they feed on the tender leaves and create holes and slimy trails. Slugs and snails are more active at night or during rainy weather, and hide under mulch, debris, or pots during the day. To prevent slugs and snails, use copper tape, diatomaceous earth, or eggshells around your lettuce plants, remove any hiding places, and handpick and dispose of them regularly. You can also use organic baits or traps, such as beer, yeast, or iron phosphate, to lure and kill them.

• Aphids are small, soft-bodied insects that suck the sap from the lettuce leaves and stems, causing them to curl, wilt, or turn yellow. Aphids can also transmit viral diseases and secrete honeydew, which attracts ants and fungal growth. Aphids are usually found on the undersides of the leaves, in clusters or colonies. To prevent aphids, use reflective mulch, row covers, or companion plants, such as marigolds, nasturtiums, or garlic, to repel or confuse them. You can also spray them with a strong jet of water, or use insecticidal soap, neem oil, or horticultural oil to kill them.

• Caterpillars are the larvae of various moths and butterflies that chew holes in the lettuce leaves and stems, or tunnel into the heads. Caterpillars can be green, brown, black, or striped, and vary in size and shape. Some of the most common caterpillars that attack lettuce are cabbage loopers, cutworms, armyworms, and corn earworms. To prevent caterpillars, use row covers, netting, or collars to exclude them from your lettuce plants, and inspect and remove them by hand regularly. You can also use biological controls, such as Bacillus thuringiensis (Bt), a bacteria that kills caterpillars, or beneficial insects, such as parasitic wasps, lacewings, or ladybugs, that prey on them.

Lettuce is a delicious and nutritious vegetable that you can easily grow in your garden or container. By choosing the right variety, sowing the seeds properly, caring for the plants, and harvesting them at the right time, you can enjoy fresh and crisp lettuce throughout the season. You can also prevent or treat common problems and pests that may affect your lettuce, and ensure a healthy and productive crop. Lettuce is a versatile and rewarding crop that you can use in many dishes, or simply enjoy on its own. Happy gardening!