How to Grow Stevia
Stevia rebaudiana
Stevia is a tender, warmth-loving herb grown for its intensely sweet leaves. Start seeds indoors at 20–25°C on the surface of moist compost — seeds need light to germinate. Transplant outdoors only after all frost risk has passed and nights stay above 12°C. Pinch out flower buds the moment they appear; flowering sharply reduces leaf sweetness. Harvest leaves regularly before any flowers open for the best flavour. A light feeder — fortnightly liquid feed is plenty. Can be overwintered on a bright indoor windowsill by cutting back and reducing water.
When to Start
Start seeds indoors 5 weeks before your last frost date. Transplant outdoors once night temperatures stay above 11°C and soil has warmed to at least 18°C.
Don't know your frost date? Find it here →
Growth Stages
Approximate days from start
Care Essentials
- Light liquid feed every 2–3 weeks. Stevia is a light feeder — overfeeding reduces leaf sweetness.
- Stevia is a frost-sensitive perennial grown as an annual in temperate climates. It needs warmth and humidity similar to basil. Short days trigger flowering, which reduces leaf sweetness — keep plants in long-day conditions as long as possible. Can be overwintered indoors on a bright windowsill.
Growing Conditions
- Min. soil temperature
- 18°C+
- Germination temperature
- 20–25°C
Pet Safety
- Sow indoors
- —
- Transplant out
- —
- First harvest
- —
Want your full season plan with reminders? Try Leaftide free
Spacing & Planting
| Plant spacing | 30 cm |
| Row spacing | 45 cm |
| Sow depth | 0 cm |
| Mature height | 60 cm |
| Mature spread | 40 cm |
Allows good air circulation and room for bushy growth. Space closer only if harvesting very frequently.
Pests & Diseases
Pest Aphids
Identification: Small soft-bodied insects clustering on new growth and shoot tips; sticky honeydew residue on leaves
- Insecticidal soap spray
- Strong water spray to dislodge
- Encourage ladybirds and lacewings
- Approved systemic insecticides
Pest Whitefly
Identification: Tiny white flying insects on undersides of leaves; leaves become sticky and yellowed
- Yellow sticky traps
- Insecticidal soap spray
- Biological control (Encarsia formosa in greenhouse)
- Approved contact insecticides
Disease Powdery Mildew Various species
Symptoms: White powdery coating on leaves and stems, more common in warm dry conditions with poor air circulation
Treatment: Improve air circulation, remove affected leaves, apply sulphur-based fungicide if severe
Prevention: Good ventilation, avoid overcrowding, water at soil level, avoid wetting foliage
Disease Root Rot Pythium spp.
Symptoms: Wilting despite moist soil, yellowing leaves, dark mushy roots
Treatment: Improve drainage, reduce watering, remove affected plants
Prevention: Well-draining compost, avoid waterlogging, do not overwater
Growing Conditions
| Min. soil temperature | 18°C |
| Germination temperature | 20–25°C |
| Base growth temperature | 11°C |
| Photoperiod sensitivity | short day |
Frequently Asked Questions
- How far apart should I plant Stevia?
- Plant Stevia 30cm apart with 45cm between rows.
- When can I harvest Stevia?
- Stevia is ready to harvest approximately 60 days after transplanting.
- Is Stevia frost hardy?
- Stevia is classified as Tender.
