Mint in Zone 9A — Texas

Mint is a fantastic herb to grow in Texas, offering a refreshing flavor that complements both sweet and savory dishes. Imagine a cool mint julep on a hot summer day or fresh mint in your tabbouleh. Plus, the satisfaction of harvesting your own herbs, especially in our long growing season, is hard to beat.

Our unpredictable weather and the potential for extreme heat can be challenging, but with a little planning, you can successfully grow mint. Our long 293-day growing season gives you plenty of time to establish your mint and enjoy multiple harvests.

Starting mint from seed indoors is an option, though most Texas gardeners find it easier to propagate from cuttings or divisions. If you want to start indoors, begin in mid December through early January, giving the seedlings about 8 weeks to develop before transplanting. Use seed trays 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.

Remember to water from the bottom to avoid damping off. With our early spring character, you want to be ready to get those seedlings in the ground as soon as the weather allows.

Transplant your mint outdoors mid February through mid March. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Texas sunshine and temperature swings.

Plant them 18-24 inches apart. Mint spreads aggressively, so consider planting it in a container to keep it from taking over your garden. You can also get starts or divisions from another gardener.

Mint thrives in moist soil, which can be a bit of a challenge with our unpredictable rainfall and hot-to-extreme summer heat. During the spring and fall, when temperatures are milder, aim to water deeply about once a week, providing about 1 inch of water.

In the heat of summer, you may need to water every other day, or even daily, depending on rainfall and how well your soil retains moisture. Use the finger test: stick your finger about 2 inches into the soil. If it feels dry, it's time to water. Water at the base of the plant to avoid wetting the leaves, especially with our variable humidity, which can encourage fungal diseases.

Signs of underwatering include wilting leaves and dry, brittle stems. Overwatering can lead to yellowing leaves and root rot. A layer of mulch around your mint plants will help retain moisture and regulate soil temperature, which is especially helpful in our Texas climate.

Pruning mint is essential to keep it from taking over your garden and to encourage healthy growth. Regularly harvest entire stems, cutting them back to just above a leaf node. This encourages the plant to branch out and produce more leaves.

Throughout the growing season, pinch off any flower buds that appear to keep the plant focused on leaf production. Towards the end of the season, as the first frost approaches in early December, you can cut the plant back to the ground. It will likely return in the spring.

You can expect your first harvest of mint from mid April through early June, about 60 days after transplanting. The leaves are most flavorful before the plant flowers, so harvest regularly to encourage continued leaf production.

Harvest by snipping off stems with scissors or pruning shears. Avoid pulling the leaves off, as this can damage the plant. You can harvest mint continuously throughout the growing season. As the first frost approaches in early December, harvest as much mint as you can and dry or freeze it for later use.

Here are some common problems Texas gardeners encounter with mint:

Rust

• What it looks like: Rusty orange, yellow, or brown pustules on leaves and stems, mostly on undersides. Leaves yellow and drop prematurely.
• What causes it: Various rust fungi that spread via wind-borne spores. Favored by warm, humid conditions with moisture on leaves.
• How to fix/prevent it: Remove affected leaves. Avoid overhead watering. Improve air circulation. Apply sulfur or copper fungicide. Don't work among wet plants. Rotate crops.

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. Release predatory mites (Phytoseiulus persimilis). Avoid broad-spectrum pesticides that kill predators.

Invasive Spreading

• What it looks like: Mint popping up everywhere in your garden where you don't want it.
• What causes it: Mint's aggressive growth habit, sending out runners both above and below ground.
• How to fix/prevent it: Plant mint in containers or raised beds to contain its spread. Regularly monitor and remove any runners that escape.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems, and sometimes fruit. 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. Plant resistant varieties.

Texas Specific Challenges: The combination of hot-to-extreme heat, variable humidity, and unpredictable rainfall in Texas can create conditions that favor both fungal diseases and pests. Be vigilant about monitoring your mint plants and take action quickly to address any problems. Also, watch out for fire ants when you're working in your garden!

Mint is a great companion plant for several vegetables in your Texas garden. It repels pests like aphids and cabbage moths, making it a good choice for planting near tomatoes, peppers, cabbage, and broccoli. The strong scent of mint can also deter flea beetles from attacking your cabbage and broccoli.

Avoid planting mint near parsley and chamomile. Mint can inhibit the growth of parsley, and chamomile prefers drier conditions than mint.