Borage, an annual herb native to the Mediterranean region also known by its superhero name “star flower,” has been planted and consumed since the time of the Romans. Since being introduced to North America, borage has taken root in many parts of Canada and the northern United States where it can now be found both growing wild and in many a garden. Aside from being aesthetically pleasing with blue, pink, or white flowers, this herb is frequently grown for its edible stalks and leaves that, when added to salads or summer cocktails, offer a refreshing flavor reminiscent of cucumbers. It’s also a wonderful companion plant as it attracts bees and other beneficial insects while repelling pests. This herb has also been used in traditional medicine for hundreds of years in many parts of the world as a tea or tincture for everything from improving heart and lung health to lifting the spirits. Borage is a prolific self-seeder, so although there are many uses for this lovely herb, we suggest trimming it back a few times a season to prevent it from taking over your garden.
Seed Depth: 1/4–1/2″
Space Between Plants: 1″
Space Between Rows: 18–24″
Germination Soil Temperature: 50–70°F
Days for Germination: 5–8
Sow Indoors: Not recommended. Borage has a large tap root and doesn’t like to be transplanted. It’s relatively hardy, so there’s little advantage to planting this herb indoors.
Sow Outdoors: 1 week before average last frost. Ensure that seeds are completely covered as they need total darkness to germinate. Can be continuously sown every month or so throughout the growing season.
Vegetative: Can be propagated from cuttings done in the spring but does best from seed.
Plant in early to mid spring in USDA Zones 5–9 to be harvested throughout the summer. Borage will do best in a sunny and semi-arid environment. In the US, it’s most often found growing wild along much of the coasts, though it doesn’t seem to care for the extreme humidity and heat of tropical climates.
Natural: Full sun to partial shade. While the seeds need total darkness to germinate, once sprouted, the plants prefer sunny spots in the garden.
Artificial: HID or T5 fluorescent lamps will help get your plants growing.
Soil: An unfussy herb, borage will grow well in almost all types of soils and can even be considered to prefer poorer quality, sandy soil. A pH of between 6.0 and 7.0 will keep your plants happy and healthy.
Soilless: Similar to growing a tuber or rhizome, borage has a large dense taproot, so a sand culture or well-rotted manure mixture with perlite will be necessary.
Hydroponics: Can be grown hydroponically using a system such as a deep water culture system that would accommodate its taproot.
Water: Requires low to moderate levels of watering. Thanks to its deep tap root, borage is relatively drought resistant but still doesn’t care for overly dry soil. Aim to give your plants a good soak of about .5″, 1–2 times per week.
Nutrients: Although not a heavy feeder, a potassium-based fertilizer such as kelp meal or hardwood potash can help your plants produce larger flowers.
Pruning: Pinch back and deadhead flowers periodically to promote new growth and reduce self-seeding.
Mulching: Mulch with grass clippings or wood chips to avoid weeds that would compete for moisture.
Other: May require staking due to its top-heavy spray of flowers.
Pest(s): Virtually pest free!
Disease(s): Also virtually disease free!
Companions: Grows particularly well with tomatoes, strawberries, and cabbage but is a good companion plant for almost all species.
Harvest: In late summer to early fall, harvest flowers and/or leaves as needed. Some sources recommend harvesting the leaves before flowering—when its sharp, spiky hairs haven’t yet appeared. These hairs will soften when cooked, however, so this isn’t always necessary and depends on your needs.
Storage: Flowers should be used immediately, while leaves and stems, although best when used fresh, can be refrigerated for 3–4 days in a sealed plastic bag. Leaves and stems may also be frozen. Dry the leaves to use as an herb. To dry, hang upside down by stems in a warm, dry location.
Fun Fact: This herb has been used throughout history for treating every malady from the common cold to mending a broken heart. Perhaps the most interesting use of this herb was by Roman soldiers who used to consume it in wine before battle to lift their spirits and give them courage.
Preserve: You can candy the flowers or preserve the leaves as a dried herb—to use in a tea—in an airtight container in a cool dark cabinet. The flowers may also be frozen in ice cubes for a refreshing summer treat.
Prepare: The leaves and stems have a cucumber-like taste and are great when added to a salad or used as a garnish. They may also be cooked down and used as one would spinach or any other leafy green. The flowers also have a sweet honey taste and are often used to decorate desserts.
Nutritional: A low-calorie herb whose contents include multiple phytochemicals such as calcium, potassium, manganese, copper, zinc, and magnesium, as well as vitamin(s) A, B, and C.
Medicinal: A source of gamma linolenic acid, a concentrated essential oil distilled from the vegetative parts of borage has been used to treat arthritis by restoring joint health. Traditional medicine suggested the use of borage as a cooling agent for fevers and topically for inflammation and swelling.
Warnings: Always read proper ratios and suggested ingestion amounts. Borage promotes more oxygen to the heart (which can be good and bad) and can cause liver damage in excess. Avoid entirely if pregnant.