Borage is an easy, fast-growing, annual herb with vivid blue flowers and the flavor and scent of cucumbers. While it is considered an herb, it's often grown as a flower in vegetable gardens, where it is considered a good companion plant for tomatoes, squash, and strawberries. It’s even supposed to deter tomato hornworms and improve the flavor of tomatoes growing nearby.
Borage is a somewhat gangly plant, but you barely notice that because the star-shaped flowers hanging in downward-facing clusters are so vibrant. It also boasts a greenish-gray stem and leaves that are covered in a prickly fuzz, which acts as a deterrent for insects. Borage should be planted in the early spring. While people do eat the leaves, technically they are toxic both to people and pets.
|Common Name||Borage, starflower, tailwort|
|Botanical Name||Borago officinalis|
|Plant Type||Annual, herb|
|Size||1–3 ft. tall, 9–18 in. wide|
|Sun Exposure||Full sun, partial sun|
|Soil pH||Acidic, neutral, alkaline (4.5–8.5)|
|Hardiness Zones||2–11 (USDA)|
|Toxicity||Toxic to people, toxic to pets|
How to Plant Borage
When to Plant
Plant borage in the garden in the early spring after the threat of frost has passed. Or start seeds indoors three to four weeks before your area's projected last frost. Transplant seedlings into the garden once the soil has warmed, making sure to harden them off first (gradually acclimate them to outdoor conditions).
Selecting a Planting Site
Borage can tolerate a variety of soil conditions as long as there is good drainage. Make sure to select a spot that gets at least four hours of direct sunlight on most days, watching out for taller plants nearby that might shade the borage as they grow in the spring. Borage also can be grown in containers.
Spacing, Depth, and Support
Borage is most commonly planted from seeds, as nursery plants aren't typically available. Plant seeds 1/4 to 1/2 inch deep. Thin seedlings when they are 6 to 8 inches tall to a spacing of 18 to 24 inches apart. A support structure won't be necessary.
Borage will grow in full sun to partial shade. However, growing borage plants in full sun will give you the best chance at a plant with lots of blooms and stocky stems.
Borage can thrive even in dry, nutrient-poor soils. However, it prefers a moderately moist, well-drained soil. It also can tolerate a fairly wide soil pH range, though it likes a slightly acidic soil. Amending your soil with organic matter, such as compost, will help to give your plants a nutritional boost.
As your borage is growing from seed and getting established in your garden, water it at least every few days to keep the soil evenly moist but not soggy. Once the plant is mature, you can allow the soil to dry out between waterings.
Temperature and Humidity
Borage is a particularly hardy herb, able to withstand temperatures on both ends of the spectrum. However, while it is tolerant of both heat and cool weather, it won't be able to withstand a hard frost. It has no special humidity needs.
Borage plants in poor soil will benefit from periodic feeding with any fertilizer labeled for use on edible plants, following label instructions. Fertilizer that's high in phosphorous will help the plants to flower.
Borage self-pollinates and tends to attract bees and other pollinators to the garden.
Types of Borage
Most gardeners plant the pure species plant, Borago officinalis. However, there are two common cultivars, as well as a closely related species:
- Borago officinalis ‘Variegata’ has white mottling on the green leaves. Its flowers are less intense than common borage.
- Borago officinalis ‘Alba’, also called white borage, blooms later in the season than the blue varieties with lovely white flowers. 'Alba' is a sturdier plant than common borage.
- Creeping borage (Borago pygmaea) is a sprawling species with pale blue flowers that bloom from late spring to late fall. It is a short-lived perennial species.
Borage vs. Comfrey
Borage and comfrey are both flowering plants from the Boraginaceae family. They look similar to one another when they’re not in bloom. However, their flowers can be used to tell them apart. Borage flowers are typically blue while comfrey flowers are pink, purple, and white. In addition, comfrey generally grows in clumps while borage can be more sprawling.
Borage will reach maturity in about eight weeks after planting, at which point you can harvest the leaves and flowers as needed. The plants will start to decline if they are not deadheaded and are left to go to seed. Staggering your planting times will give you a longer bloom period, along with a longer harvest time.
Simply pick off the leaves and flowers you need by hand, or use garden scissors. They are best eaten fresh after harvesting, though you also can keep them in the refrigerator for a few days. Borage can add a bit of cucumber flavor and color to salads, soups, dips, beverages, and ice cubes. Chop the leaves finely for use in cooking. The young stalks are also edible; prepare them as you would celery or similar vegetables.
How to Grow Borage in Pots
Growing borage in a pot is a great option if you don’t have the garden space for it. Use a container that’s at least 12 inches deep with ample drainage holes. An unglazed clay container is ideal because it will allow excess soil moisture to escape through its walls. Note that container-grown plants will typically need more frequent watering than those grown in the ground, though you shouldn't allow the soil to become soggy.
Regularly deadheading the plants, or removing the spent blooms, will encourage them to keep blooming for several weeks. Also, if you prune back borage by one-half in the midsummer, it will grow tender new leaves for a late summer harvest.
Borage is typically propagated via seeds, but it also can be grown from volunteer plants that sprout up after a mature plant has self-seeded. This is a quick and inexpensive way to cultivate new plants. Here's how:
- Gently dig up a volunteer seedling when it's at least 6 inches tall, keeping its roots as intact as possible. Wetting the soil around it first can help to slide out the roots.
- Replant the seedling at the same depth it was previously growing in a suitable growing site.
- Water to moisten the soil.
How to Grow Borage From Seed
Borage plants produce lots of black seeds, which can be collected to plant the following spring. Simply shake the seeds from the flowers as the blooms degrade, and store them in an airtight container. Then, once the weather has warmed in the spring, shake them over the soil in your preferred growing site, and cover them with 1/4 to 1/2 inch of soil. Water to keep the soil lightly moist but not soggy.
Potting and Repotting Borage
A well-draining, all-purpose potting mix will do for container-grown borage. The plant doesn't take well to transplanting, so aim to pot in a large container to make repotting unnecessary.
Borage is an annual that completes its life cycle in one season, so overwintering isn't a concern. It self-seeds very freely, so if you don't want lots of volunteer plants, it's best to pull the plants from the ground at the end of the season. Borage also rots easily, so it makes a great addition to compost heaps.
Common Pests and Plant Diseases
There are few pest or disease problems with borage. Powdery mildew can occur, especially in subpar growing conditions. Making sure there is air circulation around the plants and that they are properly watered can help to prevent the fungal disease.
Is borage easy to grow?
Borage is an easy grower in many different conditions, and it typically doesn't have pest or disease issues.
How long does it take to grow borage?
Borage will mature in about eight weeks after planting.
Will borage come back every year?
Borage is an annual, completing its life cycle in one growing season.