Romaine Lettuce in Zone 7A — Southeast

Romaine lettuce is a fantastic addition to any Southeast garden. Its crisp texture and slightly bitter flavor elevate salads, sandwiches, and even grilled dishes. Plus, growing your own means you get to enjoy fresh, flavorful lettuce without the wilt and potential bitterness that comes from store-bought varieties that have been shipped from far away.

While our hot and humid summers can present challenges, the long 225-day growing season gives you plenty of opportunities to grow Romaine successfully. By timing your plantings right, you can avoid the worst of the heat and enjoy a steady supply of delicious lettuce from spring through fall.

Starting Romaine lettuce indoors is optional, but it can give you a head start, especially for the spring crop. If you want to get a jump on the season, sow your seeds indoors from early to late February, about four weeks before you plan to transplant them outside.

Use seed trays or small pots filled with a good seed-starting mix. Keep the soil consistently moist by bottom watering – set the tray in a shallow container of water and let it soak up from the bottom. This helps prevent damping off. Place the trays under grow lights or in a sunny window. Our spring weather can be moderate, so having the option to start indoors is a great way to get ahead.

Transplant your Romaine lettuce seedlings outdoors from mid March through early April, once the danger of a hard frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Choose a spot that gets full sun to partial shade. Space the plants 8-10 inches apart. Keep an eye on the weather forecast. While Romaine is semi-hardy, a late cold snap could still damage young transplants, so be ready to cover them if needed.

Direct sowing is a great option for Romaine lettuce, especially for succession planting throughout the growing season. Sow seeds directly into the garden from late February through mid August. You have about a 6-month window.

Prepare the soil by loosening it and adding compost. Make shallow furrows and sow seeds about ½ inch deep, spacing them 8-10 inches apart. Thin seedlings as needed. Direct sowing is less work than starting indoors, but you'll need to keep the soil consistently moist, especially during germination.

Consistent watering is key for growing crisp, tender Romaine lettuce in the Southeast. Aim to keep the soil consistently moist, but not waterlogged. Our wet-summer rainfall can make this tricky.

In the spring and fall, when temperatures are cooler, you may only need to water once or twice a week, providing about 1 inch of water each time. During the hot and humid summer months, you may need to water more frequently, especially if we're experiencing a dry spell between afternoon thunderstorms. Stick your finger about 2 inches deep into the soil to check moisture levels. If it feels dry, it's time to water.

Water at the base of the plants to avoid wetting the leaves, which can increase the risk of fungal diseases in our humid climate. Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to root rot and yellowing leaves. A layer of mulch, like pine straw or shredded leaves, can help retain moisture and suppress weeds.

You can expect your first Romaine lettuce harvest from early May through mid November, depending on when you planted. Romaine lettuce is ready to harvest when the outer leaves are 6-8 inches long, or when the entire head feels firm and full-sized.

To harvest individual leaves, simply snap off the outer leaves as needed, leaving the inner leaves to continue growing. For a whole head harvest, cut the stem at the base of the plant. To encourage continued production, avoid letting the center stem elongate, which indicates the plant is bolting.

As the first frost approaches in early November, harvest any remaining mature heads or cover the plants with a frost blanket to extend the season a bit longer.

Here are some common problems you might encounter growing Romaine lettuce in the Southeast:

Bolting in Heat

• What it looks like: A tall flower stalk emerges from the center of the lettuce head. The leaves become tough and bitter.
• What causes it: Extended periods of warm temperatures, especially when days consistently exceed 80°F, trigger bolting.
• How to fix/prevent it: Time your plantings for cooler weather in spring and fall. Choose bolt-resistant varieties. Provide shade during the hottest part of the day with shade cloth. Mulch to keep the soil cool. Harvest lettuce before bolting progresses.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: These sap-sucking insects thrive in warm weather and can quickly multiply.
• How to fix/prevent it: Blast aphids off plants with a strong stream of water. Encourage natural predators like ladybugs and lacewings. Apply insecticidal soap or neem oil for heavy infestations.

Slugs

• What it looks like: Irregular holes in leaves, especially on lower leaves. Silvery slime trails on leaves and soil.
• What causes it: Slugs are nocturnal pests that thrive in moist conditions.
• How to fix/prevent it: Set out beer traps (shallow dishes of beer sunk into the soil). Use iron phosphate bait (pet-safe). Remove hiding spots like mulch and debris. Water in the morning so the soil surface dries out by evening.

Tip Burn

• What it looks like: Brown, dried edges on the inner lettuce leaves.
• What causes it: Calcium deficiency due to inconsistent watering or high temperatures.
• How to fix/prevent it: Water consistently to maintain even soil moisture. Avoid fertilizers high in ammonium nitrogen. Ensure good soil calcium levels. Choose tip burn-resistant varieties. Provide shade during hot spells.

Southeast Specific Challenges: The combination of hot heat, humid humidity, and wet-summer rainfall creates ideal conditions for fungal diseases and pest infestations. Careful monitoring, proper watering techniques, and proactive pest control measures are essential for successful Romaine lettuce growing in our region.

Companion planting can help you grow healthier Romaine lettuce in the Southeast.

Good companions:

• Carrots: Carrots help deter lettuce root aphids.
• Radishes: Radishes are fast-growing and can help break up the clay soil we often have. They also deter flea beetles.
• Strawberries: Strawberries act as a living mulch, helping to keep the soil cool and moist.
• Chives: Chives deter aphids and other pests.
• Onions: Onions also deter aphids and other pests.

Bad companions:

• Celery: Celery competes with lettuce for nutrients and water.
• Parsley: Parsley attracts aphids, which can then spread to your lettuce.