Borage in Zone 9A — Northern California

Borage is a fantastic addition to any Northern California garden. The cheerful blue flowers are not only beautiful but also attract pollinators, and the leaves and flowers have a refreshing cucumber-like flavor, perfect for summer salads and drinks. Plus, it's incredibly satisfying to grow something so useful and attractive in our Mediterranean climate.

Our dry summers and occasional water restrictions can present challenges, but Borage is surprisingly adaptable. With a little attention to watering and strategic placement, you can enjoy a bountiful harvest throughout our long, 288-day growing season.

You can transplant Borage seedlings outdoors from early February through early March. This gives them a head start before the warmer weather arrives.

Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Start with a few hours of shade and increase the sun exposure each day. Space the plants 12-18 inches apart to allow for their mature size.

Keep an eye on the weather forecast during this time. We sometimes get late frosts or unexpected temperature swings in February and early March, so be prepared to cover your seedlings if necessary.

Direct sowing Borage is the easiest and most common method, and it works well in our Northern California climate. You can sow seeds directly into the garden from mid February through late September.

Choose a sunny to partially shaded spot with well-drained soil. Borage isn't too fussy, but a little compost mixed in will help get them going. Sow seeds about ½ inch deep and 12-18 inches apart. Keep the soil consistently moist until germination, which usually takes about a week or two.

Borage is known for readily self-seeding, so be prepared to have new plants popping up in unexpected places! If you don't want them everywhere, you can deadhead the flowers before they go to seed.

Borage needs moderate watering, especially during our dry summers. While it's not particularly drought-tolerant, it's generally an easy-going plant that can handle most conditions once established. Getting your watering schedule dialed in is crucial in NorCal, given our unique climate.

During the cooler spring and fall months, you'll only need to water once or twice a week, providing about 1 inch of water each time. In the heat of summer, especially when temperatures are consistently in the 80s, increase watering to 2-3 times a week, ensuring the soil stays consistently moist. 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 fungal diseases in our low-humidity environment. 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 plant will help retain moisture and suppress weeds, which is especially helpful during our long, dry summers.

You can expect your first Borage harvest starting in mid April and continuing through mid December, depending on when you sowed the seeds. Borage is ready to harvest about 55 days after sowing.

Harvest the star-shaped blue flowers when they are fully open. The young leaves are also edible and can be harvested throughout the growing season. They have a mild, cucumber-like flavor.

To harvest, simply snip off the flowers or leaves with scissors or your fingers. Regular harvesting encourages continued production. As our first frost approaches in early December, you can harvest any remaining flowers and leaves to use in teas or salads. The plant will likely die back with the frost, but it may self-seed for the following year.

Here are a few common problems you might encounter with Borage in Northern California:

Self-Seeding Aggressively

• What it looks like: Numerous Borage seedlings popping up in unwanted areas of the garden.
• What causes it: Borage readily self-seeds, especially in our mild climate with a long growing season.
• How to fix/prevent it: Deadhead the flowers before they go to seed to prevent unwanted seedlings. You can also pull up any unwanted plants as they appear. Consider growing Borage in containers to limit its spread.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems. Leaves curl, yellow, and die.
• What causes it: Powdery mildew thrives in warm days, cool nights, and moderate humidity, which can occur in certain microclimates or during specific times of the year in Northern California. Dry leaf surfaces actually favor it.
• How to fix/prevent it: Improve air circulation by spacing plants appropriately and pruning if necessary. Remove affected leaves. Neem oil or potassium bicarbonate sprays can help. Milk spray (1 part milk to 9 parts water) is also effective.

Can Become Leggy

• What it looks like: Long, weak stems with sparse foliage, especially if not getting enough light.
• What causes it: Insufficient sunlight, particularly in shadier microclimates or as the plant matures.
• How to fix/prevent it: Ensure Borage receives at least 6 hours of sunlight per day. Prune back leggy stems to encourage bushier growth. Consider providing support, such as a stake or trellis, if the plant becomes too tall and weak.

Northern California Specific Challenges: Our moderate-to-hot summers, low humidity, and dry-summer rainfall can impact Borage. While the plant is relatively easy to grow, providing adequate water during dry periods and ensuring good air circulation to prevent powdery mildew are essential for success in our region.

Borage is a great companion plant for several vegetables and herbs in your Northern California garden. It attracts pollinators, which benefits tomatoes, squash, strawberries, and cucumbers, increasing their yields. It is thought to deter tomato hornworms. The flowers also attract beneficial insects like lacewings and ladybugs, which prey on aphids and other pests. I haven't noticed any bad companions, but watch out if you have a small garden, it can get big!