Romaine Lettuce in Zone 9B — Texas

Romaine lettuce is a fantastic addition to any Texas garden, offering crisp, flavorful leaves perfect for salads, wraps, and even grilling. Its upright growth habit also means it takes up less space than some other lettuce varieties. Plus, with our long growing season, you can enjoy two harvests – one in spring and another in the fall.

Sure, we've got our share of challenges with the Texas heat and unpredictable weather. But with careful timing and a few tricks, you can successfully grow Romaine lettuce and enjoy fresh salads almost year-round. Our 308-day growing season gives you plenty of opportunities!

Starting Romaine lettuce indoors makes sense if you want a head start on the spring growing season. Sow seeds indoors from mid December through early January, about four weeks before you plan to transplant them outside. Use seed trays filled with a good seed-starting mix and keep them in a warm spot with plenty of light – a sunny windowsill or under grow lights works well.

Water from the bottom by placing the tray in a shallow dish of water until the soil surface is moist, then removing it. This encourages strong root growth. Because our spring can arrive early, starting indoors gives you a jump on getting those first leaves.

Transplant your Romaine lettuce seedlings outdoors in late January through mid February. Before you plant, harden them off by gradually exposing them to outdoor conditions for about a week. Start with an hour or two of shade, then slowly increase the sun exposure each day.

Plant seedlings 8-10 inches apart in well-drained soil. Keep an eye on the weather forecast – those late freezes can still happen, so be prepared to cover your seedlings if necessary.

Direct sowing Romaine lettuce is an easy option, especially for your fall garden. Sow seeds directly into the garden from early January through late September. Choose a spot with well-drained soil and prepare the bed by loosening the soil and adding compost.

Keep the soil consistently moist until the seeds germinate. Thin seedlings to 8-10 inches apart once they have a few true leaves. Direct sowing is great for getting a continuous harvest, but remember the soil temperature needs to be cool enough for germination.

Consistent watering is key to growing crisp, delicious Romaine lettuce in Texas. With our unpredictable rainfall, you can't rely on Mother Nature alone. During the spring and fall, when temperatures are milder, aim to water deeply once or twice a week, providing about 1 inch of water each time.

Stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. In the heat of summer, you may need to water daily, especially if the humidity is low. Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our variable humidity.

Underwatering can lead to bitter leaves and tip burn, while overwatering can cause root rot. Yellowing leaves are a sign of overwatering. Mulching around your plants with straw or shredded leaves helps retain moisture and keep the soil cool, which is crucial during the Texas heat.

You can expect your first Romaine lettuce harvest starting in mid March and continuing through mid December. Romaine lettuce is ready to harvest about 65 days after planting. Look for outer leaves that are 6-8 inches long, or harvest the whole head when it feels firm and full-sized.

To harvest individual leaves, simply snip them off from the outside of the plant, 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, don't let the center stem elongate, which signals bolting.

As our first frost approaches in early December, harvest any remaining heads to enjoy before the cold weather sets in. You can also try covering your plants to extend the harvest a bit longer.

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

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 periods of warm temperatures, especially when days consistently exceed 80°F. This is common in Texas as spring transitions to summer.
• 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 well 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 and curled or distorted new growth.
• What causes it: Rapidly reproducing sap-sucking insects that thrive in warm weather. Fire ants may even protect them!
• How to fix/prevent it: Blast aphids off plants with a strong stream of water. Encourage ladybugs and lacewings. Use insecticidal soap or neem oil for heavy infestations. Avoid over-fertilizing with nitrogen.

Slugs

• What it looks like: Irregular holes in leaves, especially on lower leaves. Silvery slime trails on leaves and soil. Damage is worse at night.
• What causes it: Slugs are gastropods that feed at night in moist conditions. They hide under mulch and debris during the day.
• How to fix/prevent it: Use beer traps (shallow dishes of beer sunk into the soil). Apply iron phosphate bait (pet-safe). Remove hiding spots like rocks and boards. Water in the morning so the soil surface dries out by evening. Sprinkle diatomaceous earth around plants.

Tip Burn

• What it looks like: Brown, dried edges on the inner lettuce leaves. In severe cases, it can affect the outer leaves.
• What causes it: A calcium uptake problem caused by inconsistent watering, worsened by high temperatures.
• How to fix/prevent it: Water consistently, especially during hot, dry spells. Avoid fertilizers high in ammonium nitrogen. Ensure good soil calcium levels. Choose resistant varieties. Provide shade during warm weather.

Texas Specific Challenges: The extreme heat, variable humidity, and unpredictable rainfall in Texas can all contribute to these problems. Careful watering, appropriate variety selection, and diligent monitoring are key to success.

Companion planting can help your Romaine lettuce thrive in Texas. Carrots are good companions because they deter lettuce root aphids. Radishes break up the soil and deter flea beetles. Strawberries act as a living mulch, keeping the soil cool and moist. Chives and onions repel aphids and other pests.

Avoid planting Romaine lettuce near celery or parsley. Celery competes for nutrients and water, while parsley can attract aphids. By choosing the right companions, you can create a healthier and more productive garden.