Mint in Zone 7B — Desert Southwest

Mint is a must-grow for us here in the Desert Southwest! Its refreshing flavor elevates everything from iced tea to summer salads, and there's real satisfaction in growing your own fragrant leaves. Plus, it's surprisingly adaptable to our unique climate, bringing a burst of green to your garden.

Desert gardening has its challenges, from the extreme heat to our alkaline soil, but with smart timing and a few tricks, you can absolutely grow mint successfully. Our long, 245-day growing season gives us a great advantage, and mint is one of those plants that can thrive with a little extra care.

Starting mint indoors gives you a jumpstart on the season, but honestly, it's often easier to buy a start from a local nursery or grab a division from a friend. However, if you're set on starting from seed, aim for mid January through early February, about eight weeks before you plan to transplant. Use seed trays with a good seed-starting mix, provide warmth (a heat mat helps), and ensure bright light, ideally under grow lights.

Remember to water from the bottom to avoid damping off. Place the tray in a shallow dish of water and let the soil soak it up. This is especially helpful in our dry air because it keeps the seedlings from drying out too quickly.

Transplant your mint outdoors from mid March through mid April, after the danger of any late frost has passed. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This prevents transplant shock.

Space your plants about 18-24 inches apart, or better yet, plant them in containers! Mint is notorious for spreading aggressively, and a container will keep it contained. When transplanting, remember that we can still get some unexpected cold snaps in the spring, so keep an eye on the weather and be ready to cover your plants if needed.

Watering is key to happy mint, especially with our extreme heat and arid climate. Mint likes consistently moist soil, so aim to water deeply whenever the top two inches feel dry to the touch – use the finger test.

During the hottest part of the summer, that might mean watering every other day, giving each plant about an inch of water per week. In the spring and fall, you can usually back off to twice a week. Focus on watering at the base of the plant to avoid getting the leaves wet, which can encourage fungal diseases.

Watch for wilting leaves as a sign of underwatering. Yellowing leaves, on the other hand, can indicate overwatering. A good layer of mulch, like shredded bark or straw, will help retain moisture and keep the soil cooler.

Pruning mint is simple. The most important thing is to cut it back aggressively to control its spread. Harvest entire stems regularly throughout the growing season. This encourages new growth and prevents the plant from flowering.

You can prune mint anytime it looks overgrown or leggy. Don't be afraid to cut it back hard – it will bounce back quickly. As the first frost approaches around mid- November, give your mint one final haircut, removing any dead or dying foliage. This will help it overwinter and be ready to go again in the spring.

You can expect your first harvest of mint around mid May through early July, about 60 days after transplanting. The best time to harvest is before the plant starts to flower, as the leaves are most flavorful then.

Simply pinch or cut off stems as needed, leaving a few inches of growth. Regular harvesting encourages continued leaf production, so don't be shy! Pinch off any flower buds as they appear to keep the plant focused on producing leaves.

As the weather cools down in late fall, harvest as much mint as you can before the first frost. You can dry the leaves for later use or make mint extract. Even if the plant dies back in winter, it will usually return in the spring.

Mint is generally easy to grow, but here are a few problems you might encounter in the Desert Southwest:

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 thrive in 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. Avoid broad-spectrum pesticides.

Invasive Spreading

• What it looks like: Mint popping up everywhere you don't want it!
• What causes it: Mint spreads via underground runners (rhizomes) and can quickly take over a garden bed.
• How to fix/prevent it: Plant mint in containers or raised beds to contain its spread. If planting in the ground, bury a barrier around the plant to prevent the runners from escaping. Regularly pull up any unwanted shoots.

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.

Desert Southwest Specific Challenges: The extreme heat of our summers can stress mint, making it more susceptible to pests and diseases. Our arid humidity means spider mites are a constant threat. While the monsoon season provides welcome moisture, it can also create conditions that favor fungal diseases. Be vigilant about watering and monitoring your plants, and take action quickly if you spot any problems.

Mint can be a great companion plant for several vegetables. It's said to deter pests from tomatoes and peppers, while also attracting beneficial insects. Cabbage and broccoli also benefit from mint's pest-repelling properties.

Avoid planting mint near parsley or chamomile. Mint can inhibit the growth of parsley, and chamomile prefers drier conditions than mint. Since we're gardening in the Desert Southwest, remember that intense sun is a big factor. If you're pairing mint with sun-loving plants like tomatoes, be sure to provide some afternoon shade to protect the mint from sunscald.