Borage in Zone 9B — Southern California

Borage is a fantastic addition to any Southern California garden. Its cucumber-flavored leaves and beautiful blue, star-shaped flowers are edible and add a unique touch to salads and drinks. Plus, it attracts beneficial pollinators to your garden, which is always a win in our mild climate.

We all know SoCal gardening comes with its own set of challenges, from water restrictions to summer heat inland. But with a long growing season like ours, around 334 days, and a little planning, you can easily grow borage and enjoy its benefits for months.

You can transplant borage seedlings outdoors from mid January through early February in our area. Make sure you harden them off first by gradually exposing them to the outdoors for about a week. Start with an hour or two of shade and increase the time and sun exposure each day.

Space your borage plants about 12-18 inches apart to give them plenty of room to grow. Keep an eye on the weather forecast around transplant time. We sometimes get unexpected cold snaps, so be ready to cover your young plants if necessary.

Direct sowing is the recommended method for borage, and it's super easy! You can sow seeds directly into your garden bed from late January through mid October. Borage germinates best when the soil temperature is around 60-70°F, so aim for a time when the soil has warmed up a bit, especially for later sowings.

Prepare your soil by loosening it and mixing in some compost. Sow seeds about 1/2 inch deep and 12-18 inches apart. Keep the soil consistently moist until the seedlings emerge. Borage is known to self-seed readily, so be prepared for volunteer plants in the future.

Borage needs moderate watering, which means being mindful of our SoCal climate. During our hotter, drier months, especially inland, you'll need to water more frequently than during the winter-wet season.

A good rule of thumb is to water deeply once or twice a week, providing about 1 inch of water each time. Use the finger test to check the soil moisture before watering – if the top 2 inches feel dry, it's time to water. Watering at the base of the plant is generally best, but with our low-to-moderate humidity, overhead watering in the early morning is usually fine too.

Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to root rot, so watch out for yellowing leaves and a generally unhealthy appearance. Mulching around your borage plants with a few inches of organic mulch helps retain moisture and regulate soil temperature, which is especially helpful during the summer heat inland.

You can expect your first borage harvest around late March through early January, about 55 days after sowing. Look for the star-shaped blue flowers to be fully open. These are edible and make a beautiful garnish.

The young leaves are also edible and have a refreshing cucumber-like flavor. Harvest them regularly to encourage continued production. Simply snip off the leaves or flowers as needed, being careful not to damage the main stem.

As we approach late December and the possibility of our first frost, continue to harvest as usual. Borage is fairly hardy, but a hard frost can damage the leaves. Even if the plant dies back, it will likely self-seed, giving you a head start for next year.

Here are a few common problems you might encounter with borage in Southern California:

Self-Seeding Aggressively

• What it looks like: Numerous borage seedlings popping up in unwanted areas of your garden.
• What causes it: Borage is a prolific self-seeder, and our long growing season in SoCal allows it to produce seeds for much of the year.
• How to fix/prevent it: Deadhead flowers before they go to seed. Remove unwanted seedlings 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, and sometimes flowers. Leaves may curl, yellow, and die.
• What causes it: Powdery mildew thrives in warm days, cool nights, and moderate humidity, which we often experience, especially near the coast. Dry leaf surfaces actually favor it.
• How to fix/prevent it: Improve air circulation by spacing plants appropriately and pruning if needed. Remove affected leaves promptly. Treat with neem oil or potassium bicarbonate sprays. A milk spray (1 part milk to 9 parts water) can also be effective.

Can Become Leggy

• What it looks like: Tall, sparse growth with fewer leaves, especially towards the base of the plant.
• What causes it: Insufficient sunlight or nutrient deficiencies can cause borage to become leggy.
• How to fix/prevent it: Ensure your borage plants receive at least 6 hours of sunlight per day. Amend the soil with compost or a balanced fertilizer to provide essential nutrients. Prune back leggy stems to encourage bushier growth.

Southern California Specific Challenges: Our hot summer heat inland can stress borage plants, making them more susceptible to powdery mildew and leggy growth. Santa Ana winds can also dry out the soil quickly, so consistent watering is crucial. While borage isn't particularly drought-tolerant, mulching and careful watering can help it thrive even during water restrictions.

Borage is a great companion plant for several vegetables and herbs in our Southern California gardens. It attracts pollinators, which benefits tomatoes, squash, strawberries, and cucumbers by increasing fruit production. It's also said to deter tomato hornworms.

I haven't noticed any truly *bad* companions for borage, but avoid planting it too close to anything that prefers very dry soil, as borage needs moderate moisture.