Romaine Lettuce in Zone 8B — Florida

Romaine lettuce is a winner in Florida because of its crisp texture and mild flavor. It's fantastic in salads, wraps, or even grilled, and growing your own means you can harvest it fresh throughout much of the year. Plus, it's incredibly satisfying to harvest your own salad ingredients right from your backyard, especially during our mild winters.

Sure, Florida gardening has its quirks – humidity, nematodes, and the occasional hurricane – but with a little planning, you can absolutely enjoy a thriving Romaine lettuce crop. Our long 303-day growing season gives you plenty of opportunities to plant in fall and harvest in winter when the weather is much more favorable.

Starting Romaine lettuce indoors is an option, especially if you want a head start on the season. Begin late December through mid January, about four weeks before you plan to transplant. This gives the seedlings time to develop before the weather warms up too much.

Use seed trays or small pots filled with a good seed-starting mix. Keep the soil consistently moist by watering from the bottom – set the tray in a shallow dish of water until the surface soil is damp. Provide warmth and plenty of light, either from a sunny windowsill or a grow light. Remember, our spring character is reversed, so starting early helps you get ahead of the heat.

Transplant your Romaine lettuce seedlings outdoors early February through early March. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sunlight and temperature changes.

Space the plants about 8-10 inches apart in well-drained soil. Keep an eye on the weather forecast – those early weeks can still bring unexpected cool snaps, so be ready to cover your seedlings if a frost threatens.

Direct sowing Romaine lettuce is a straightforward way to get a crop going, and you can do it Mid January through late September. Prepare your garden bed by loosening the soil and removing any rocks or debris. Romaine lettuce seeds need soil temperatures between 45°F and 75°F to germinate well.

Sow the seeds about ¼ inch deep and 8-10 inches apart. Keep the soil consistently moist until the seedlings emerge. Direct sowing works best in cooler months, as the summer heat can cause the seeds to struggle.

Watering Romaine lettuce properly is key to getting crisp, flavorful leaves, especially with our Florida climate. During the cooler months (fall through spring), aim to water deeply once or twice a week, providing about 1 inch of water each time. Use the finger test: stick your finger about 2 inches into the soil. If it feels dry, it's time to water.

In the hotter, more humid summer months, you might need to water more frequently, but be careful not to overwater. Overhead watering can increase the risk of fungal diseases in our humid environment, so try to water at the base of the plants. Signs of underwatering include wilting leaves, while yellowing leaves and mushy stems indicate overwatering.

Mulching around your lettuce plants with pine straw or wood chips helps retain moisture and keep the soil cool. This is especially important during the warmer parts of the year.

You can expect your first Romaine lettuce harvest late March through late December, about 65 days after planting. Look for outer leaves that are 6-8 inches long, or harvest the entire head when it feels firm and full-sized. The key is to harvest before the center stem starts to elongate, which indicates bolting.

To harvest individual leaves, simply snip them off near the base of the plant, allowing the inner leaves to continue growing. For a whole head, cut it off at the base with a sharp knife. This method encourages continued production.

As our first frost approaches around mid- December, harvest any remaining heads to enjoy before the cold weather sets in. You can also cover the plants with a frost blanket for a little extra protection.

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

Bolting in Heat

• What it looks like: A tall flower stalk emerges from the center of the lettuce, and the leaves become bitter and tough.
• What causes it: Extended warm temperatures above 80°F signal the plant to reproduce.
• How to fix/prevent it: Time your plantings for cooler weather. Choose bolt-resistant varieties. Provide shade with row covers or shade cloth during warm spells. Mulch to keep the soil cool. Harvest leaves as soon as they are ready.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. Sticky honeydew and curled or distorted new growth.
• What causes it: Rapidly reproducing sap-sucking insects thrive in warm weather.
• How to fix/prevent it: Spray them off with a strong stream of water. Encourage natural predators like ladybugs. Use insecticidal soap or neem oil if needed. Avoid excess nitrogen fertilizer.

Slugs

• What it looks like: Irregular holes in leaves, especially on low-growing plants. Silvery slime trails on leaves and soil.
• What causes it: Night-feeding gastropods that love moist conditions.
• How to fix/prevent it: Set out beer traps. Use iron phosphate bait (safe for pets). Remove hiding spots like mulch and debris. Water in the morning so the soil surface dries out by evening. Use copper tape around beds or diatomaceous earth around plants.

Tip Burn

• What it looks like: Brown, dried edges on the inner lettuce leaves, sometimes affecting outer leaves.
• What causes it: Calcium uptake problems due to inconsistent watering, often worsened by high temperatures.
• How to fix/prevent it: Water consistently. Avoid fertilizers high in ammonium nitrogen. Ensure good soil calcium levels. Choose resistant varieties. Provide shade during warm spells.

Florida Specific Challenges: The combination of hot heat, very-high humidity, and our wet-summer rainfall can create the perfect conditions for fungal diseases and bolting in Romaine lettuce. Careful watering practices, proper spacing for air circulation, and choosing the right varieties are essential for success. Nematodes can also be a problem in our sandy soil, so consider soil solarization or using nematode-resistant varieties.

Good companion plants for Romaine lettuce in Florida include carrots, radishes, strawberries, chives, and onions. Carrots and radishes help break up the soil, improving drainage, which is crucial in our sometimes heavy rains. Strawberries make a good ground cover, helping to suppress weeds and keep the soil cool. Chives and onions repel aphids and other pests, protecting your lettuce from infestations.

Avoid planting Romaine lettuce near celery and parsley. Celery competes for nutrients and water, while parsley attracts swallowtail butterflies, whose caterpillars can munch on your lettuce leaves.