Borage in Zone 5B — Mountain West

Borage is a fantastic addition to any Mountain West garden. Its edible, star-shaped blue flowers and cucumber-flavored leaves add a unique touch to salads and drinks. Plus, it's a bee magnet, which helps pollinate your other crops in our short growing season.

Our high altitude, intense sun, and cool nights present unique challenges, but borage handles them well. With a 149-day growing season, you'll find that direct sowing at the right time makes growing borage in our zone entirely manageable.

While direct sowing is best, you can start borage indoors about 4 weeks before the last expected frost. Harden off your seedlings by gradually exposing them to the outdoors for about a week. This is key to avoid shock from our intense UV.

Transplant borage seedlings outdoors from late April through mid May, spacing them 12-18 inches apart. Keep an eye on the weather forecast; a late frost can still happen in the Mountains. Protect young transplants with row covers if needed.

Direct sowing is the preferred method for borage in our region. Sow seeds directly into well-drained soil from early May through late July. Borage prefers a soil temperature of around 60-70°F for optimal germination.

Prepare the soil by loosening it and amending with compost. Sow seeds about 1/2 inch deep and 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 in subsequent years!

Borage needs moderate watering, especially in our dry Mountain West climate. While it's relatively easy-going, consistent moisture is key for good growth. Our low humidity means you'll need to be more attentive than in other regions.

During the hotter parts of summer, aim to water deeply about once a week, providing around 1 inch of water. 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 foliage, which can help prevent powdery mildew.

Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch around the base of the plants can help retain moisture and regulate soil temperature, which is especially helpful with our intense sun.

You can expect your first harvest of borage flowers and leaves starting in late June and continuing through early October. Borage matures quickly, generally about 55 days after sowing. The star-shaped blue flowers are ready to harvest when they are fully open.

Harvest the young leaves when they are tender and have a good cucumber flavor. Simply snip off the flowers or leaves as needed, being careful not to damage the main plant. Regular harvesting encourages continued production.

As the first frost approaches in early October, harvest any remaining flowers and leaves. You can also let some flowers go to seed if you want borage to self-seed in your garden next year.

Here are common problems you might encounter with borage in the Mountain West:

Self-seeding aggressively

• What it looks like: Numerous borage seedlings popping up everywhere in your garden, even in unwanted areas.
• What causes it: Borage readily self-seeds, and the seeds can remain viable in the soil for several years. This is especially true in our climate, where the seeds can overwinter easily.
• How to fix/prevent it: Deadhead flowers before they go to seed. Pull out unwanted seedlings as soon as you see them. Consider growing borage in containers to limit its spread.

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). Our cool nights and low humidity can create conditions favorable for powdery mildew.
• 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.

Can become leggy

• What it looks like: Tall, spindly plants with sparse foliage and weak stems.
• What causes it: Insufficient sunlight or overcrowding. Borage needs full sun to part shade, and our high altitude sun can be very intense.
• How to fix/prevent it: Ensure plants receive adequate sunlight. Thin out crowded plantings to improve air circulation and light penetration. Prune back leggy stems to encourage bushier growth.

Mountain West Specific Challenges: Our moderate-at-altitude heat, low humidity, and dry rainfall can stress borage plants if they are not watered adequately. The intense UV radiation can also scorch leaves if plants are not properly acclimated. Monitor your plants closely and adjust your watering and care as needed.

Borage is a great companion plant for several vegetables and herbs in our Mountain gardens. It attracts beneficial insects and can even improve the flavor of some crops.

Good companions include tomatoes, squash, strawberries, and cucumbers. Borage attracts pollinators to tomato and squash flowers, increasing fruit set. It also repels tomato hornworms. For strawberries, borage is said to improve their disease resistance. Borage attracts beneficial insects that prey on cucumber pests.

There are no significant bad companions for borage, so plant freely!