Romaine Lettuce in Zone 10B — Florida

Romaine lettuce is a fantastic addition to the Florida garden, offering a crisp, refreshing taste in salads, wraps, and even grilled preparations. Nothing beats the satisfaction of harvesting your own fresh greens during our mild winters, a welcome change from the summer heat.

While our subtropical climate presents challenges like humidity and nematodes, Romaine lettuce thrives during our reversed growing seasons. With careful timing and attention, you can enjoy a continuous harvest of this versatile vegetable throughout much of our 360-day growing season.

Starting Romaine lettuce indoors gives you a head start, especially if you want to maximize your winter harvest. Begin sowing seeds from mid-November through early December, about four weeks before you plan to transplant them. Use seed trays with a good seed-starting mix and keep them consistently moist, using bottom watering to prevent damping off.

Maintain a warm environment and provide ample light, either from a sunny window or a grow light. Remember our spring character is reversed, so getting seedlings established early is key.

Transplant your Romaine lettuce seedlings outdoors from late December through mid-January. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Florida sunshine and temperature swings.

Space the seedlings 8-10 inches apart in well-drained soil. Be mindful of unexpected cold snaps that sometimes hit us during this time of year and have frost cloth ready to protect your young plants.

Direct sowing Romaine lettuce is a viable option, especially for a continuous harvest. Sow seeds from early December through mid-October, ensuring the soil temperature is between 60-70°F for optimal germination. Prepare the soil well, ensuring it's loose and fertile.

Thin seedlings to 8-10 inches apart once they emerge. Keep in mind that direct-sown lettuce might take slightly longer to mature than transplants, but it eliminates the need for indoor setup.

Romaine lettuce needs consistent moisture to produce crisp, tender leaves. In Florida's climate, where we often swing between dry spells and heavy rainfall, monitoring soil moisture is crucial. Stick your finger about two inches deep into the soil; if it feels dry, it's time to water.

During our drier fall and winter months, aim for about 1 inch of water per week, either through rainfall or irrigation. Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our humid environment. Overwatering can lead to root rot, while underwatering causes wilting and tip burn. A good layer of mulch, like pine straw, helps retain moisture and suppress weeds.

In our wet summer, you may not need to water much at all, but ensure that the plants have good drainage.

Expect your first Romaine lettuce harvest from mid-February through early January, about 65 days after planting. You can harvest outer leaves as needed when they reach 6-8 inches in length, or harvest the entire head when it feels firm and full-sized. Cut the head at the base, leaving the root intact if you want it to potentially regrow.

To encourage continued production, avoid letting the center stem elongate, as this signals the plant is bolting. As late December approaches and our first frost looms, harvest any remaining mature heads to avoid frost damage.

What it looks like: A tall flower stalk emerges from the center of the lettuce head. The leaves become bitter and tough. What causes it: Extended periods of warm temperatures, a common occurrence even during our "cool" season in Florida. How to fix/prevent it: Time your plantings to avoid the hottest months. Choose bolt-resistant varieties. Provide shade with row covers during warm spells. Harvest lettuce promptly as it matures.

What it looks like: Clusters of tiny green, black, or white insects on stems and undersides of leaves. Sticky honeydew and distorted growth. What causes it: Rapid reproduction in warm, humid conditions. Ants often protect them. How to fix/prevent it: Blast aphids off with a strong stream of water. Introduce ladybugs. Apply insecticidal soap or neem oil.

What it looks like: Irregular holes in leaves, especially at night. Silvery slime trails. What causes it: These pests thrive in moist conditions and are abundant after rainfall. How to fix/prevent it: Use beer traps. Apply iron phosphate bait. Remove debris where slugs hide. Water in the morning. Use diatomaceous earth.

What it looks like: Brown, dried edges on inner lettuce leaves. What causes it: Calcium deficiency due to inconsistent watering, exacerbated by high temperatures. How to fix/prevent it: Water consistently. Ensure good soil calcium levels. Provide shade.

Florida Specific Challenges: Our hot, humid summers make Romaine lettuce a cool-season crop only. The extreme humidity encourages fungal diseases, so proper spacing and watering at the base are crucial. Even in winter, warm spells can trigger bolting, so monitor the weather and be ready to harvest early.

Good companions for Romaine lettuce in Florida include:

• Carrots: They deter some pests that might bother lettuce and their roots loosen the soil.
• Radishes: They germinate quickly, marking rows and breaking up the soil, plus they deter flea beetles.
• Strawberries: They provide ground cover and benefit from the lettuce's shade.
• Chives and Onions: Their strong scent repels aphids and other pests.

Avoid planting Romaine lettuce near:

• Celery: Both compete for the same nutrients in the soil.
• Parsley: It can attract aphids that will then spread to your lettuce.