Romaine Lettuce in Zone 9B — Florida

Romaine lettuce is a winner in the Florida garden. Its crisp texture and mild flavor make it perfect for salads, wraps, or even a quick grilling. Growing your own means you get to enjoy fresh, flavorful lettuce right from your backyard, without the grocery store markup or questionable freshness.

Florida gardening calendar is different, and summer is the slow season. But with our long, 344-day growing season, we can easily grow romaine during the cooler months. By timing your planting right, you can avoid the worst of the heat and humidity that can cause problems.

Starting Romaine lettuce indoors in Florida isn't strictly necessary, but it can give you a head start. If you want to get a jump on the season, aim to start your seeds indoors in early to late December, about four weeks before you plan to transplant.

Use seed trays or small pots filled with a good seed-starting mix. Keep them in a warm location, around 70°F, and provide plenty of light – a simple grow light works great. Bottom watering is the way to go to avoid damping off. Remember, our spring character is reversed here, so you are trying to get a jump before the temperatures start to rise.

Transplant your Romaine lettuce seedlings outdoors in early January through early February. Before transplanting, 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 your plants 8-10 inches apart in well-drained soil. Be mindful of the Florida weather during this time. We can still get some chilly nights, so be prepared to cover your seedlings if a frost is predicted.

Direct sowing Romaine lettuce is a great option in Florida, especially if you want to avoid the extra step of transplanting. Sow your seeds directly into the garden in late December through mid October.

Prepare the soil by loosening it and adding some compost. Sow the seeds about ¼ inch deep and keep the soil consistently moist. Thin the seedlings to 8-10 inches apart once they emerge. Direct sowing is simple, but you do have to watch out for heavy rains washing away the seeds.

Watering Romaine lettuce correctly is essential for success in Florida's climate. Our wet-summer rainfall doesn't extend to the winter, so you will need to supplement. Aim for consistent moisture, as this helps produce crisp, tender leaves. However, avoid overwatering, which can lead to fungal diseases, especially with our very-high humidity.

During the cooler months, water deeply about once or twice a week, providing around 1 inch of water. 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 months, you may need to water more frequently, but be careful not to overdo it.

Water at the base of the plants to avoid wetting the leaves, which can encourage fungal growth. Overhead watering during our humid months is not ideal. Signs of underwatering include wilting leaves, while overwatering can lead to yellowing and root rot.

Mulching around your lettuce plants with pine straw or wood chips helps retain moisture and suppress weeds. This is especially important in our sandy soil, which tends to drain quickly.

You can expect your first Romaine lettuce harvest in late February through early January, 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.

To harvest individual leaves, simply cut them off near the base of the plant. This allows the inner leaves to continue growing, giving you a continuous harvest. For a whole head, cut it off at the base with a sharp knife.

As late December approaches and the risk of frost increases, harvest any remaining heads to prevent damage. You can also cover your plants with a frost blanket if a freeze is predicted to extend your harvest a bit longer.

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

Bolting in Heat

• 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 warm temperatures above 80°F trigger bolting.
• How to fix/prevent it: Time your plantings for the cooler months (spring/fall). Choose bolt-resistant varieties. Provide shade during warm spells. Mulch to keep the soil cool. Harvest lettuce before it bolts.

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: Rapidly reproducing sap-sucking insects. Populations explode in warm weather.
• How to fix/prevent it: Spray aphids off with a strong stream of water. Encourage ladybugs and lacewings. Use insecticidal soap or neem oil for heavy infestations. 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: Gastropods that feed at night in moist conditions.
• How to fix/prevent it: Use beer traps or iron phosphate bait. Remove hiding spots like mulch and debris. Water in the morning so the soil surface dries out by evening. Apply diatomaceous earth around plants.

Tip Burn

• What it looks like: Brown, dried edges on inner lettuce leaves.
• What causes it: Calcium uptake problem caused by inconsistent watering and 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 weather.

Florida Specific Challenges: The hot heat and very-high humidity in Florida create a perfect environment for fungal diseases and pests. Consistent monitoring and preventative measures are key to keeping your Romaine lettuce healthy. Our wet-summer rainfall patterns can also cause issues with soil moisture, so well-draining soil is essential.

Companion planting can be a great way to improve your Romaine lettuce crop in Florida. Carrots are good companions because they deter lettuce aphids. Radishes help break up the soil and can act as a trap crop for flea beetles.

Strawberries make a good ground cover that helps retain moisture and suppress weeds. Chives and onions can repel certain pests with their strong scent. Avoid planting celery and parsley near lettuce, as they can attract the same pests and compete for nutrients.