How to Grow Lettuce and Salad Greens
By: Julie Day
Lettuce is an easy to grow cool-weather crop.
Lettuce and salad greens are favorites in the spring and fall garden. They’re easy to grow and work exceptionally well in raised beds, cold frames, and containers. And with a little planning, you can keep the harvest going throughout much of the year.
Here’s what you need to know about growing lettuce in your garden.
The many varieties of lettuce are usually divided into four categories:
- Leaf Lettuce: From red to green leaf and many varieties in between, leaf lettuce is the most popular and easiest to grow of all lettuces. It forms a loose bunch of leaves growing out of a central stalk, and it can be repeat harvested. It’s the most heat-tolerant type and is easily grown from seed.
- Cos (Romaine) Lettuce: This type has the texture similar to leaf lettuce but grows upright on a firmer stalk that can be harvested as a head.
- Head (Crisphead) Lettuce: Like the familiar iceberg you see in the supermarket, head lettuce requires a long season of cool weather and is usually grown in northern climates. In warmer areas, the season usually isn’t long enough to grow it from seed. Head lettuce is the most challenging type of lettuce to grow, with only one head produced per plant.
- Butterhead Lettuce: Buttercrunch and Bibb lettuce are the most popular varieties of butterhead lettuce. The tender, sweet leaves grow in an open, loose-head shape.
Lettuce Growing Conditions
- Climate: Lettuce is a cool-season vegetable that thrives when daytime temperatures are in the 60s to 70s and can tolerate a very light frost. It can be grown in spring and fall, and even over the winter in a greenhouse. The midsummer heat spells trouble for lettuce – causing it to go to seed (bolting) and loose flavor.
- Light: Lettuce requires five hours of sunshine a day. Because it doesn’t like the heat, lettuce does well with an eastern exposure with some afternoon shade.
- Soil: Lettuce prefers a light, rich soil with plenty of organic matter to hold moisture, and a pH around 6.5. Lettuce only needs 6” – 8” of soil, so it’s great for containers and raised beds.
- Water: Water content is the secret to producing tender, crisp leaves. Lettuce must be kept evenly watered or it will become tough.
- Maturity: If grown from seed, leaf lettuce can be harvested in about two months while head types take three months.
Lettuce getting a head start in a cold frame.
Lettuce Planting Tips
- Direct Seeding: Lettuce is most popularly grown from seed directly in the garden.
- Timing: Plant lettuce seeds or transplants about 2-4 weeks before your last frost date in spring, or about 6-8 weeks before your first frost date in the fall. Continue planting every two weeks, but take a break at least a month before hot summer weather arrives in your area.
- Planting: Plant lettuce seeds 1/4”-1/2” deep. Once they sprout, thin your plants so that they aren’t crowded. Leaf lettuces should be 4” apart, Cos and Butterhead about 8” apart, and Head lettuce about 12” apart. Use the thinnings in a baby green salad!
- Harvesting: To keep from being overwhelmed by your lettuce harvest, do successive plantings every two weeks, and you’ll have salad all season.
- Starting Seeds Indoors: You can also start seeds over the winter indoors or in a greenhouse. This is a great way to get a head start on your harvest before the weather gets too hot. Because lettuce can be difficult to transplant, use biodegradable peat pots that can be planted directly in the garden.
- Cold Frame: Lettuce is also perfect for cold frames, and you can take advantage of sunny days in late winter to get a head start on the spring season.
- Plants: If you decide to buy plants instead of seeds, choose ones in plantable pots, or buy preplanted containers for your patio.
Consistent watering is very important with lettuce.
Lettuce Growing Tips
- Water: Watering will make (or break) your lettuce harvest. Keep seedlings and plants evenly moist (but not soggy), and be prepared to irrigate your lettuce as the season warms. Lettuce does best with frequent light watering, rather than a “drought-and-flood” approach. Water in the morning to prevent overnight dampness and mold growth.
- Fertilizer: If you’ve focused on giving your lettuce the light, rich soil it loves, it won’t require much fertilizer.
- Diseases and Pests: The most common problems with lettuce are downy mildew and gray mold (caused by cool, wet weather), rot (common in hot, humid climates), aphids, greenflies, slugs, and critter damage (deer and rabbits). Brown tips on lettuce leaves, know as tipburn, usually indicates uneven watering. Clipping off the dead leaves and watering lightly and more frequently to cure.
Red leaf lettuce.
- Leaf Lettuce: Harvest any time the leaves are of desirable size. Use scissors, or carefully pinch off leaves. For extended harvest, just cut part of the leaves, leaving the plant to produce more.
- Head Lettuce: Harvest when the head is fully formed and firm. Use shears or a sharp knife to cut the stalk and harvest the entire head.
- Bolting: Bolting, or going to seed, happens when the weather gets hot. The stalk grows taller and, eventually, a flowering seed head will form. If your lettuce is starting to bolt, harvest it immediately. Once the flower stalk has formed, most people throw away the plants, although you can use the stalks in soups.
- Preserving: Lettuce is a fresh-only vegetable; it can’t be frozen, canned, or otherwise preserved. Plan your harvest to keep a steady supply throughout the season.
- Storage and Serving: Store fresh dry lettuce in the fridge; the cooler the better, but don’t let it freeze. Wash and pat dry just before serving. For best results, tear your lettuce into bite-size pieces, rather than cutting it, since cut edges quickly discolor.
- Vegetable Gardening: Growing Cool-Season Vegetables
- How to Plant a Fall Vegetable Garden
- Lettuce (University of Illinois Extension)
- How To Grow Lettuce (vegetablegardenguide.com)