Romaine Lettuce in Zone 7A — Texas

Romaine lettuce is a must-grow for Texas gardeners. Its crisp texture and mild flavor make it perfect for salads, wraps, and even grilling. Plus, you can often get two harvests – one in spring and another in fall.

Our unpredictable weather can be a challenge, but Romaine is relatively cold-hardy, giving you a good window to grow it. With our long 245-day growing season, you can enjoy fresh lettuce from your garden for a good portion of the year.

Starting Romaine indoors is an option, especially if you want a head start on the spring season. Begin in late January through mid February, giving you about 4 weeks to get seedlings ready for transplanting. This can be helpful to get ahead of the Texas heat.

Use seed trays or small pots with a good seed-starting mix. Keep them warm and provide plenty of light – a grow light works wonders. Don't forget to water from the bottom to encourage strong root growth and prevent damping off.

Transplant your Romaine seedlings outdoors in early to late March. Before you do, harden them off for about a week by gradually exposing them to outdoor conditions. This helps them adjust to the Texas sun and wind.

Plant them 8-10 inches apart in well-drained soil. Keep an eye on the forecast for any late freezes, and be prepared to cover them if needed. Those temperature swings can be brutal on young plants.

Direct sowing Romaine is easy and works well in our climate. Sow seeds from mid February through late August, giving you plenty of options for spring and fall crops. For a fall harvest, late August through late September is ideal.

Prepare the soil by loosening it and adding compost. Sow seeds about ¼ inch deep and keep the soil consistently moist until they germinate. Thin seedlings to 8-10 inches apart once they have a few true leaves.

Romaine needs consistent moisture to produce crisp, tender leaves. Aim for about 1 inch of water per week, adjusting for rainfall. Remember, our rainfall can be unpredictable, so don't rely on it.

Check the soil moisture by sticking your finger in about 2 inches deep. If it feels dry, it's time to water. Water at the base of the plants to avoid wetting the leaves, which can encourage disease, especially with our variable humidity.

Underwatering leads to bitter, tough leaves, while overwatering can cause root rot. Signs of underwatering include wilting and yellowing leaves. Signs of overwatering include yellowing leaves and stunted growth. Mulching around your plants helps retain moisture and keeps the soil cool, which is crucial during our hot summers.

You can expect your first harvest of Romaine in late April through late November. Start harvesting outer leaves when they reach 6-8 inches in length, or harvest the whole head when it's firm and full-sized. It's best to cut it before the center stem starts to elongate, as this indicates bolting.

To harvest, simply cut the outer leaves with a sharp knife, leaving the inner leaves to continue growing. This allows for continuous harvest throughout the season. As the first frost approaches in mid- November, harvest any remaining heads to prevent damage.

Here are some common problems you might encounter with 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 above 80°F. Our Texas heat can trigger bolting quickly.
• How to fix/prevent it: Time your plantings for cooler parts of the year (spring and fall). Choose bolt-resistant varieties. Provide shade during the hottest part of the day. Mulch to keep the soil cool. Harvest 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. Curled or distorted new growth.
• What causes it: Rapidly reproducing sap-sucking insects. Warm weather encourages their population growth.
• How to fix/prevent it: Knock them off with a strong spray of water. Encourage natural predators like ladybugs. Use insecticidal soap or neem oil for heavy infestations.

Slugs

• What it looks like: Irregular holes in leaves, especially on low-growing plants. Silvery slime trails on leaves and soil.
• What causes it: These pests feed at night in moist conditions.
• How to fix/prevent it: Use beer traps. Apply iron phosphate bait. Remove hiding spots like mulch and debris. Water in the morning so the soil surface dries out by evening.

Tip Burn

• What it looks like: Brown, dried edges on inner lettuce leaves.
• What causes it: Calcium uptake problems due to inconsistent watering and high temperatures.
• How to fix/prevent it: Water consistently and deeply. Ensure good soil calcium levels. Provide shade during warm weather.

Texas Specific Challenges: The extreme heat, variable humidity, and unpredictable rainfall in Texas can make growing Romaine challenging. Consistent watering is key, but avoid overwatering, especially during periods of high humidity. Be prepared to provide shade during the hottest parts of the summer to prevent bolting.

Companion planting can help your Romaine thrive. Carrots are good companions because they deter lettuce root aphids. Radishes break up the soil and deter pests. Strawberries provide ground cover and attract beneficial insects. Chives and onions deter aphids and other pests with their strong scent.

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