Rosemary in Zone 7A — Texas

Rosemary is a fantastic addition to any Texas garden. Its pungent, piney flavor elevates countless dishes, and its evergreen foliage provides year-round interest. Plus, the satisfaction of snipping fresh rosemary sprigs, even during our mild winters, is hard to beat.

While the Texas heat and unpredictable weather can be challenging, rosemary is surprisingly well-suited to our climate if you get the timing right. With our long, 245-day growing season, you can enjoy rosemary for years to come.

Starting rosemary from seed indoors is possible, but let's be honest, it's not the easiest route for Texas gardeners. Rosemary seeds have a reputation for erratic germination and slow growth, so unless you're up for a challenge, you might consider buying established plants.

If you're determined to start from seed, begin in late December through mid January. Use seed trays with a well-draining seed-starting mix. Keep them consistently warm (around 70-75°F) and provide plenty of light, either from a sunny window or a grow light. Bottom watering can help prevent damping-off. Remember, with our early spring, you'll want to get a jump start.

Transplanting rosemary outdoors is best done in late March through mid April, after the danger of any late freezes has passed. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Plant rosemary 24-36 inches apart in a sunny spot with well-draining soil. Keep an eye on the weather forecast. Even in late March and April, we can still get some unpredictable temperature swings, so be prepared to cover your young plants if a cold snap threatens. Since rosemary is slow and difficult from seed, consider buying established plants from your local nursery.

Rosemary thrives on neglect when it comes to watering, which is a good thing, considering our unpredictable rainfall here in Texas. Once established, it's very drought-tolerant and prefers dry conditions. Overwatering is the quickest way to kill rosemary.

During the hottest parts of the Texas summer, from mid-June through August, water deeply about once every 1-2 weeks if we haven't had significant rainfall. Use the "finger test" – stick your finger about 2 inches into the soil. If it feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or irrigation. Water at the base of the plant to avoid creating a humid environment around the foliage, which can encourage fungal diseases.

Signs of underwatering include wilting or drooping leaves. Overwatering can cause yellowing leaves and, eventually, root rot. A layer of mulch around the base of the plant helps retain moisture and suppress weeds, but be sure to keep the mulch away from the stem to prevent rot.

Rosemary requires minimal pruning, which is great for busy Texas gardeners. Lightly prune after flowering to maintain its shape and encourage bushier growth.

Avoid cutting into the old, woody parts of the plant, as it may not regrow from those areas. In the spring, you can shape the plant to your liking. As the first frost approaches in mid- November, you don't need to do any special pruning. Just let the plant go dormant and resume pruning in the spring.

You can start harvesting rosemary in late June through early August, about 90 days after transplanting. The best time to harvest is in the morning, after the dew has dried but before the heat of the day sets in.

Harvest 4-6 inch stem tips. Never take more than one-third of the plant at a time to avoid stressing it. The woody stems are generally too tough to eat, so stick to the newer growth. Regular harvesting encourages continued production.

As the first frost approaches in mid- November, harvest any remaining sprigs you want to use and dry or freeze them for later. The plant itself will usually survive our winters without any special protection.

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

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting, and eventually, the entire plant collapses. The roots will be brown and mushy.
• What causes it: Overwatering and poor drainage. Our heavy clay soils, combined with unpredictable rainfall, can easily lead to waterlogged conditions.
• How to fix/prevent it: Plant rosemary in well-draining soil or raised beds. Water sparingly, allowing the soil to dry out between waterings. Avoid overwatering, especially during periods of heavy rainfall.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems. Leaves curl, yellow, and die. Reduces plant vigor.
• What causes it: Various fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it (unlike most fungi).
• How to fix/prevent it: Improve air circulation through spacing and pruning. Remove affected leaves. Neem oil or potassium bicarbonate sprays help. Milk spray (1 part milk to 9 parts water) is surprisingly effective.

Spider Mites

• What it looks like: Fine stippling on leaves (tiny white dots). Fine webbing on leaf undersides and between stems. Leaves turn bronze or yellow.
• What causes it: Tiny arachnids that thrive in hot, dry conditions. Populations explode in drought stress.
• How to fix/prevent it: Strong water spray (daily for a week) is the best treatment. Increase humidity around plants. Neem oil or insecticidal soap.

Texas Specific Challenges: The combination of hot-to-extreme heat, variable humidity, and unpredictable rainfall can create ideal conditions for both overwatering and fungal diseases. Monitor your plants closely and adjust your watering schedule accordingly. Also, fire ants can sometimes build mounds around rosemary plants, so be sure to keep them under control.

Rosemary makes a great companion plant for several vegetables and herbs in your Texas garden. Sage, thyme, and lavender all share similar growing requirements (full sun, well-draining soil) and can create a beautiful and fragrant herb garden together. Green beans benefit from rosemary's ability to repel bean beetles. Carrots also appreciate rosemary as it deters the carrot rust fly.

Avoid planting rosemary near mint. Mint is incredibly invasive and can quickly outcompete rosemary for resources. Plus, mint prefers consistently moist soil, which is the opposite of what rosemary needs.