Borage in Zone 10B — Desert Southwest

Borage is a fantastic addition to any Desert Southwest garden. The star-shaped blue flowers are edible and beautiful in salads, plus the young leaves have a refreshing cucumber-like taste. It's a rewarding plant to grow, providing both culinary interest and attracting beneficial pollinators to your garden.

While our extreme heat and arid conditions present challenges, the extended growing season in our Zone 10B Desert Southwest climate gives you ample time to enjoy borage. With our 349-day growing season, you can easily grow borage in the cooler months, avoiding the worst of the summer heat.

You can transplant borage seedlings outdoors in early to late January. Make sure to harden them off first. This means gradually exposing the seedlings to outdoor conditions for about a week before transplanting.

Space the plants 12-18 inches apart. Keep an eye on the weather forecast. Even in January, we can experience temperature swings, so protect young transplants from unexpected cold snaps if needed.

Direct sowing borage is the recommended method in our climate. You can direct sow from mid January through late October, giving you a wide window to work with. Soil temperatures between 60-70°F are ideal for germination.

Prepare your garden bed by loosening the soil and amending with compost. Sow seeds about ½ inch deep, spacing them 12-18 inches apart. Keep the soil consistently moist until seedlings emerge. Borage is easy to direct sow and self-seeds readily, so be prepared for volunteers!

Borage needs moderate watering, especially during our hot, dry months. While it's fairly easy-going, it's definitely not drought-tolerant. In the Desert Southwest, a consistent watering schedule is key.

During the cooler months (late fall, winter, early spring), water deeply once a week, providing about 1 inch of water. The "finger test" is a good guide—if the top 2 inches of soil are dry, it's time to water. During our extreme heat, increase watering to 2-3 times per week, ensuring the soil doesn't completely dry out between waterings. Water at the base of the plant to avoid wetting the foliage, which can contribute to powdery mildew in our arid climate.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to root rot, indicated by yellowing leaves and a generally unhealthy appearance. A layer of mulch around the base of the plants helps retain moisture in our dry air and regulates soil temperature.

You can expect your first harvest of borage flowers and leaves starting in mid March and continuing through early January. The star-shaped blue flowers are ready to harvest when they are fully open. The young leaves are best harvested when they are tender and about 4-6 inches long.

To harvest, gently snip the flowers or leaves with scissors or pruners. Avoid pulling or tearing, which can damage the plant. Regular harvesting encourages continued production.

As our first frost approaches in late December, you can still harvest any remaining flowers and leaves. Consider letting some plants go to seed to ensure a supply of volunteers for the following season.

Here are some common problems you might encounter growing Borage in the Desert Southwest:

Self-Seeding Aggressively

• What it looks like: Numerous borage seedlings popping up in unwanted areas of your garden.
• What causes it: Borage readily self-seeds, especially in our mild winter climate.
• How to fix/prevent it: Deadhead spent flowers before they go to seed. Remove unwanted seedlings as soon as you see them. Consider growing borage in a contained area.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems, and sometimes fruit. Leaves curl, yellow, and die.
• What causes it: Various fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it.
• 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.

Can Become Leggy

• What it looks like: Long, weak stems with sparse foliage.
• What causes it: Insufficient sunlight or overcrowding.
• How to fix/prevent it: Ensure borage receives at least 6 hours of sunlight per day, especially in our less intense winter sun. Provide support if needed. Prune back leggy stems to encourage bushier growth.

Desert Southwest Specific Challenges: Our extreme heat and intense sun can stress borage, making it more susceptible to powdery mildew. The monsoon moisture can also contribute to fungal issues. Make sure to provide adequate shade during the hottest part of the day and ensure good air circulation to combat these challenges.

Borage is a great companion plant for several reasons. It attracts beneficial pollinators, which can improve the yield of nearby plants like tomatoes, squash, strawberries, and cucumbers. It can also deter certain pests.

Avoid planting borage near plants that are susceptible to powdery mildew, as it can potentially spread the disease.