Iceberg Lettuce in Zone 10B — Florida

Iceberg lettuce gets a bad rap, but homegrown, it's surprisingly flavorful and crisp. Plus, in Florida, growing your own means you can have fresh lettuce during the cooler months when store-bought prices often spike. The satisfying crunch of a homegrown Iceberg harvested from your own garden in February is hard to beat!

Sure, Florida gardening has its quirks. We know our summers are brutal, and pests are a constant battle. But with a little planning, you can absolutely grow Iceberg lettuce here. Our long, 360-day growing season gives us a great window to plant in fall and harvest in the winter.

Starting Iceberg lettuce indoors in Florida is possible, but honestly, it's usually not necessary. Direct sowing works just fine during our cooler months. However, if you want a head start, especially after an unusually hot late-fall, you can start seeds indoors from mid-November through early December, about four weeks before you plan to transplant.

Use seed trays and a good seed-starting mix. Keep the soil consistently moist, bottom watering is a great way to do this. You'll need supplemental light, as our reversed spring character means shorter days. A simple shop light works well.

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

Space the plants about 12 inches apart to give them room to form those nice, tight heads. Keep an eye on the weather forecast; even in January, a sudden warm spell can stress young transplants. Water them well after transplanting to help them settle in.

Direct sowing Iceberg lettuce seeds is a perfectly viable option in Florida, and often easier than starting indoors. You can direct sow from early December through early October. Prepare your soil by loosening it and amending with compost. Lettuce needs well-draining soil, even with our sandy conditions.

Sow seeds about ¼ inch deep and keep the soil consistently moist until they germinate. Thin seedlings to about 12 inches apart once they have a few true leaves. Direct sowing works best when soil temperatures are consistently cool.

Consistent moisture is absolutely key for Iceberg lettuce in Florida. Unlike some other leafy greens, Iceberg is more sensitive to water stress, and fluctuating moisture levels can lead to problems like tip burn. During our drier fall and winter months, aim to give your lettuce about 1 inch of water per week, either from rainfall or irrigation.

The "finger test" is your best friend. Stick your finger about 2 inches deep into the soil near the base of the plant. If it feels dry, it's time to water. Water at the base of the plant to avoid wetting the leaves, which can encourage fungal diseases in our humid environment.

Avoid overhead watering, especially in the evenings. Our high humidity means that wet leaves are prone to fungal problems. Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to root rot, so make sure your soil drains well. A good layer of mulch, like pine straw, helps retain moisture and keeps the soil cooler, which is especially helpful during those occasional warm spells.

You can expect your first Iceberg lettuce harvest from mid-February through early January, about 70 days after planting. The biggest challenge with Iceberg is knowing when it’s ready. You're looking for a firm, compact head that feels similar in size and density to what you'd find at the grocery store.

To harvest, simply cut the head at the base with a sharp knife. Once you harvest the main head, that's it – Iceberg isn't a cut-and-come-again type of lettuce. As our first frost approaches in late December, harvest any remaining heads that are close to maturity. They might not get much bigger, but they'll still be delicious in a salad.

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

Tip Burn

• What it looks like: Brown, dried edges on the inner lettuce leaves, sometimes spreading to the outer leaves.
• What causes it: Inconsistent watering is the main culprit, leading to a calcium uptake problem, similar to blossom end rot in tomatoes. High temperatures make it worse.
• How to fix/prevent it: Water consistently, especially during dry spells. Avoid fertilizers high in ammonium nitrogen. Make sure your soil has good calcium levels by amending with lime if needed. Provide shade during warm weather with shade cloth. Choose tip-burn-resistant varieties.

Bolting in Heat

• What it looks like: The lettuce plant sends up a flower stalk, and the leaves become tough and bitter.
• What causes it: Extended warm temperatures. Iceberg is a cool-season crop, and when temperatures consistently exceed its comfort zone, it bolts.
• How to fix/prevent it: Time your plantings carefully to take advantage of our cooler months. Choose bolt-resistant varieties. Provide shade during warm spells. Mulch to keep the soil cool. Harvest the lettuce as soon as it's ready to prevent bolting.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. Sticky honeydew residue and curled or distorted new growth.
• What causes it: Rapidly reproducing sap-sucking insects that thrive in warm weather.
• How to fix/prevent it: Knock them off with a strong spray of water. Encourage natural predators like ladybugs and lacewings. Use insecticidal soap for heavy infestations. Neem oil can also be effective. Avoid excess nitrogen fertilizer, which attracts aphids.

Slugs

• What it looks like: Irregular holes in the leaves, especially on low-growing plants. Silvery slime trails on leaves and soil.
• What causes it: Slugs are gastropods that feed at night in moist conditions.
• How to fix/prevent it: Use beer traps (shallow dishes of beer sunk into the soil). Apply iron phosphate bait, which is pet-safe. Remove hiding spots like mulch and debris. Water in the morning so the soil surface dries out by evening. Copper tape around beds and diatomaceous earth around plants can also help.

Florida Specific Challenges: Our hot, humid climate and wet-summer rainfall pattern can make growing Iceberg lettuce challenging. The high humidity encourages fungal diseases, and the heat can cause bolting and tip burn. Careful watering practices, good air circulation, and choosing the right varieties are essential for success.

Companion planting can be a great way to improve your Iceberg lettuce crop in Florida. Carrots are excellent companions because they deter lettuce root aphids. Radishes also help deter pests and act as a trap crop for flea beetles. Strawberries make a good ground cover, helping to keep the soil cool and moist. Chives and garlic are natural pest repellents, keeping aphids and other unwanted visitors away.

Avoid planting celery and parsley near your Iceberg lettuce. Celery attracts whiteflies, which can also infest your lettuce. Parsley can stunt the growth of lettuce. By choosing the right companions, you can create a healthier and more productive lettuce patch in your Florida garden.