Stevia
Stevia rebaudiana
Also known as: Sweet leaf, Sugar leaf, Candyleaf, Yerba dulce
Quick facts
- Category
- herbs soft
- Difficulty
- intermediate
- Days to harvest
- 90 to 150 days
- Harvest type
- cut leaves, plant regrows for repeated harvests
- Spacing
- 30 cm between plants
Environment
- Temperature
- 18–30°C
- pH
- 6 to 7.5
- EC (hydroponic)
- 1.2 to 1.8 mS/cm
- Daily light
- 16 to 24 mol/m²/day
Climate and zones
- USDA zones
- 9 to 12 (winter low around -7°C or warmer)
- Frost tolerance
- frost sensitive (dies at first frost)
- Season
- year-round tropical (needs consistent warmth)
Viable growing environments:
- outdoor in growing season (annual)
- heated greenhouse
- indoor (heated home)
- indoor hydroponics under grow lights
USDA zone bounds reflect outdoor year-round survival. Anywhere outside the bounded zone range, this crop still grows as an annual in the warm months (outdoor_seasonal), under cover (greenhouse), or indoors under lights.
Growing systems
Stevia works in:
- deep water culture (rafts)
- NFT channels
- media bed (ebb and flow)
- wicking bed
- soil bed
Growing media
The substrate the roots sit in. Choice depends on the system (clay pebbles don't fit NFT channels; rockwool isn't used in media beds) and the crop (stevia works in the media listed below).
| Medium | pH effect | Water retention | Bacterial surface |
|---|---|---|---|
| Rockwool (Mineral wool) | alkaline until pre-soaked | very high | low |
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
| Net pot, no medium (Bare-root) | - | - | - |
| Soil-based mix (Potting soil) | varies by source | high | high |
Bacterial surface area matters for aquaponics: clay pebbles, lava rock, and pumice double as biofilter substrate. Low-surface media (rockwool, perlite, pea gravel) work in hydroponics but need a separate biofilter in aquaponics.
Nutrient demand by stage
NPK ratios are relative weights at each growth stage; the nutrient mix calculator scales them to absolute grams or ml. EC targets shift through the plant's life: seedlings need a much lighter solution than fruiting adults.
| Stage | N | P | K | EC target (mS/cm) |
|---|---|---|---|---|
| seedling | 1 | 1 | 1 | 0.6 |
| vegetative | 3 | 1 | 2 | 1.5 |
Aquaponics suitability
Compatible with typical aquaponics nutrient profiles. Fish waste provides enough nitrogen for healthy growth; supplemental potassium, calcium, and iron may still be needed depending on fish stocking density.
Care notes
An easy, compact perennial herb for hydroponic systems. EC 1.0-2.0 mS/cm. pH 5.5-7.0. Temperature: 18–30°C (subtropical origin; frost-sensitive, but tolerates moderate heat). Moderate to high light (DLI 14-22 mol/m2/day; sweetness concentration increases with strong light). NFT, DWC, Kratky, or container systems. From transplant to first harvest: 6-8 weeks (propagation from seed is slow and erratic; stem cuttings or purchased plants are more practical). Harvest by cutting stem tips; the plant branches and regrows. The sweetness is concentrated in the leaves; stems have less flavor. For tea sweetening: add 2-3 fresh leaves to a cup of tea (the sweetness is intense; start small). For dried stevia powder: dehydrate leaves at 40–50°C, crush to powder, use sparingly. The dried powder has a slight herbal aftertaste that some find objectionable; the fresh leaves have a cleaner sweet flavor. A single stevia plant provides enough sweetener for a household's tea and herb-tea consumption.
Verified against: rhs-uk, university-of-florida-ifas. Last reviewed 2026-05-15.