Common Borage
Borago officinalisUSDA | Grow Zone
3-10Outdoors all year in zones 3 to 10. Anywhere colder, keep it as a houseplant. Protect it below 40°F.
- Light
- Full sun, 6-8 hours
- Water
- Deeply once a week
- Humidity
- Average household humidity
- Temperature
- 60-75°F (15-24°C)
- Difficulty
- Beginner
- Growth
- Moderate
- Mature size
- 2-3 ft tall, 1-2 ft wide
Common Borage, known for its vibrant blue flowers and culinary uses, is a delightful addition to any garden. Originating from the Mediterranean, this herb attracts pollinators and adds beauty to your landscape.
Ask Vesper about Common Borage
Ideal temperature
60-75°F is where it grows fastest. Below 40°F cold damage starts.
Spacing and harvest
- Mature size
- 2-3 ft tall, 1-2 ft wide
- Plant apart
- 12-24 in
- Frost
- Half hardy: light frost only
- First harvest
- 60-90 days from planting
Everything it needs
9 essentials at a glance
Watering
Borage prefers consistently moist soil but can tolerate short periods of drought.
Water the plant deeply once a week, allowing the top inch of soil to dry out between waterings. In hot weather, increase frequency to twice a week. Signs of over-watering include yellowing leaves and root rot, while under-watering may cause wilting and browning leaf edges.
Light
Common Borage thrives in full sun, requiring at least 6-8 hours of direct sunlight daily.
Ideal placement includes a south-facing garden bed or container that receives ample light. While it can tolerate partial shade, reduced light may lead to leggy growth and fewer flowers.
Soil
Borage prefers well-draining soil rich in organic matter, with a pH range of 6.0 to 7.0.
A mix of potting soil, compost, and perlite or sand is recommended to ensure good drainage. Avoid heavy clay soils that retain water, as this can lead to root rot.
Humidity
Borage is not particularly sensitive to humidity levels and can adapt to average household humidity.
However, if grown indoors, consider increasing humidity by misting the leaves or placing a humidifier nearby. Signs of low humidity stress include browning leaf tips and wilting.
Temperature
Borage grows best in temperatures between 60-75°F (15-24°C) and is hardy in USDA zones 3-10.
It can tolerate light frost but should be protected from extreme heat above 85°F (29°C) to prevent bolting. During colder months, provide some protection if temperatures drop significantly.
Fertilizing
Use a balanced, all-purpose fertilizer with an NPK ratio of 10-10-10 or similar.
Fertilize every 4-6 weeks during the growing season, starting in early spring. Signs of nutrient deficiency include yellowing leaves (nitrogen deficiency) and poor flowering (phosphorus deficiency).
Pruning
Prune borage to encourage bushier growth and more blooms.
Use clean, sharp scissors or pruning shears to remove spent flowers and any dead or damaged leaves. This can be done throughout the growing season, but avoid heavy pruning in late summer as the plant prepares for dormancy.
Repotting
Repot borage every 1-2 years or when it becomes root-bound.
Choose a pot that is 1-2 inches larger in diameter than the current one. Signs it needs repotting include roots growing out of the drainage holes or stunted growth. To repot, gently remove the plant from its current pot, loosen any tightly bound roots, and place it in fresh potting mix.
Propagation
Borage can be propagated through seeds or division.
For seed propagation, sow seeds directly into the garden in spring after the last frost or start indoors 4-6 weeks prior. Ensure seeds are lightly covered with soil and kept moist until germination. Division can be done in early spring or fall when the plant is actively growing.
When it's unhappy
Yellow leaves
Why it happens
Usually caused by over-watering or nutrient deficiency.
How to fix it
Check soil moisture levels and adjust watering accordingly. Fertilize with a balanced fertilizer if nutrient deficiency is suspected.
Root rot
Why it happens
Occurs due to poor drainage or over-watering.
How to fix it
Ensure the pot has adequate drainage holes and reduce watering frequency. If root rot is severe, consider repotting into fresh, dry soil.
Leggy growth
Why it happens
Insufficient light can lead to weak, elongated stems.
How to fix it
Move the plant to a sunnier location to ensure it receives at least 6-8 hours of sunlight daily.
Pest infestations (aphids, spider mites)
Why it happens
Pests are attracted to stressed plants or those with poor air circulation.
How to fix it
Regularly inspect plants, and if pests are found, treat with insecticidal soap or neem oil. Ensure good air circulation around the plant.
Bolting
Why it happens
Occurs when temperatures rise too high or days become too long.
How to fix it
Provide some shade during the hottest part of the day and harvest leaves regularly to encourage continued growth.
Care through the year
Spring
In spring, sow seeds directly into the garden or start indoors. Fertilize with a balanced fertilizer and ensure consistent watering as the plant begins to grow.
Summer
During summer, monitor for pests and water regularly, especially in hot weather. Prune spent flowers to encourage more blooms and bushier growth.
Fall
In fall, reduce watering as the plant prepares for dormancy. Consider harvesting leaves for culinary use before the first frost.
Winter
In winter, protect outdoor plants from frost and cold temperatures. If grown indoors, reduce watering and maintain a cooler environment.
Toxicity & Safety
Borage is generally considered non-toxic to pets and humans. However, excessive consumption of borage leaves may cause gastrointestinal upset. Pregnant women should avoid borage due to potential liver toxicity from pyrrolizidine alkaloids present in the plant.
Good to know
How often should I water my Common Borage?
Water Common Borage deeply once a week, allowing the top inch of soil to dry out between waterings. Increase frequency in hot weather.
What type of soil is best for Borage?
Borage thrives in well-draining soil rich in organic matter, with a pH range of 6.0 to 7.0. A mix of potting soil and compost works well.
Why are my Borage leaves turning yellow?
Yellowing leaves can indicate over-watering or a nutrient deficiency. Check soil moisture and consider fertilizing if needed.
Can I grow Borage indoors?
Yes, Borage can be grown indoors as long as it receives adequate sunlight, ideally 6-8 hours a day. Ensure good drainage and proper watering.
How do I propagate Borage?
Borage can be propagated from seeds or division. Sow seeds directly in spring or start indoors 4-6 weeks prior to the last frost.
What pests should I watch for on Borage?
Common pests include aphids and spider mites. Regularly inspect your plants and treat infestations with insecticidal soap or neem oil.
When should I prune my Borage plant?
Prune Borage throughout the growing season to remove spent flowers and encourage bushier growth. Avoid heavy pruning in late summer.
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