Borage
Borago officinalis
Also known asStarflower · Bee bush · Cool tankard · Borraja · Bourrache
Environment
The bounded range this crop tolerates.
Climate and zones
- USDA zones
- 3–10 (winter low around -40°C)
- Frost
- tolerates light frost
- Season
- cool (spring/fall)
Growing systems
Root mass: moderate.
Growing media
| Medium | pH effect | Retention | Bacterial surface |
|---|---|---|---|
| Soil-based mix (Potting soil) | varies | high | high |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
Nutrient demand by stage
NPK ratios are relative weights. EC targets shift through the plant's life.
| Stage | N | P | K | EC (mS/cm) |
|---|---|---|---|---|
| seedling | 1 | 1 | 1 | 0.6 |
| vegetative | 2 | 1 | 2 | 1.3 |
Aquaponics suitability
Compatible
Fish waste provides enough nitrogen for healthy growth. Supplemental potassium, calcium, and iron may still be needed depending on fish stocking density.
Care notes
A productive hydroponic herb grown mainly for its edible flowers. Hold EC around 1.0-1.6 mS/cm and pH 6.0-7.0. It is a cool-season annual, best at 15–25°C; heat over 28°C sends it to bolt and drops flower quality. Give moderate to high light, 14-22 mol/m2/day. Plants reach 40–80 cm and spread, so space them generously, and deep water culture or media beds suit the substantial root system. First flowers come about six to eight weeks from seed, and each plant flowers for four to eight weeks before declining. Pick individual flowers daily as they open, using them fresh or frozen; frozen borage flowers in ice cubes are a popular cocktail garnish. Young leaves, before the hairs stiffen, can go into salads or be cooked like spinach, though only in moderation given the alkaloid content. Outdoors it self-seeds aggressively, which is not an issue in a soilless system.