Important notes
ingestion of larger amounts by pets: Per ASPCA, toxic to cats, dogs and horses — the essential oils can cause vomiting and diarrhea in larger amounts. Safe for humans. ↗
planted in open ground / beds: Spearmint spreads by underground runners (rhizomes) and quickly takes over whole beds. Always keep it in a pot or crate — or sink the pot as a root barrier. ↗
Light
Part shade to full sun; most aromatic in sun. Indoors a bright spot; avoid harsh midday sun behind glass.
Watering
Likes evenly moist soil but no waterlogging. Water more in summer and in pots — let the surface dry, then water thoroughly.
Temperature
Grows best at 15–26 °C; very hardy (survives hard frost and re-sprouts in spring).
Humidity
Normal room/outdoor humidity (50–65%) is fine. Very dry air invites spider mites.
Target values by method & stage
| Stage | pH | EC (mS/cm) | Water °C | Air °C | Humidity % | Light h | Duration (days) |
|---|---|---|---|---|---|---|---|
| Germination | 6–7 | — | — | 18–24 | 60–70 | 14 | 14 |
| Vegetative | 6–7 | — | — | 15–26 | 50–65 | 14 | 60 |
| Stage | pH | EC (mS/cm) | Water °C | Air °C | Humidity % | Light h | Duration (days) |
|---|---|---|---|---|---|---|---|
| Vegetative | 5.8–6.2 | 1.6–2.4 | 18–22 | 18–24 | 50–65 | 14 | 50 |
| Stage | pH | EC (mS/cm) | Water °C | Air °C | Humidity % | Light h | Duration (days) |
|---|---|---|---|---|---|---|---|
| Vegetative | 5.8–6.2 | 1.6–2.2 | 18–22 | 18–24 | 50–65 | 14 | 50 |
Common problems
Spreads and crowds out neighbours (keep in pots). Mint rust (orange pustules) and mildew in crowded, damp conditions. Spider mites in dry indoor air. Leggy growth in too little light.
Space & Size
- Final height
- 60 cm
- Final width
- 60 cm
- Spacing
- 30 cm
- Root depth
- 20 cm
- Min. container (Soil)
- ≥ 5 L
- Min. container (DWC)
- ≥ 4 L
Pests & diseases
| Pest / Disease | Symptom | Organic treatment |
|---|---|---|
| Aphids | sticky, curled shoot tips | rinse off, beneficials, neem |
| Spider mites | fine webbing, speckled leaves (in dry air) | raise humidity, hose off, predatory mites |
| Mint leaf/flea beetle | shot-hole feeding on leaves | hand-pick, insect netting |
| Mint rust | orange-brown pustules on leaf undersides | remove infected shoots, improve airflow, cut back hard in spring |
| Powdery mildew | white, powdery coating on leaves | space out for airflow, avoid overhead watering |
Edible parts
- Leaves · edible from Vegetative — main harvest — tea, cooking, cocktails
- Flowers · edible from Flowering — edible as garnish; leaves get milder at flowering
Yield techniques
Harvest/pinch the shoot tips regularly — keeps the plant bushy and delays flowering. Leaves get milder at flowering; harvest before for strong flavour. Cut back hard in spring for fresh, healthy regrowth.
Propagation & pollination
- Method
- cutting
- Germination time
- 14 days
- Germination temp
- 18-24 °C
- Sowing depth
- 0 cm
- Pollination
- cross
- Hand pollination needed
- no
Very easy: cut a stem below a node, strip lower leaves, root in water in 1–2 weeks. Also by rhizome division. Seed is slow and not true to type.
Companion planting
🟢 Good neighbours: Tomato
🔴 Bad neighbours: Parsley
Not yet linked: Brassica oleracea var. capitata, Pisum sativum, Matricaria chamomilla
Flavor
sweet and fresh, grassy, clearly milder than peppermint (low menthol)
Storage
In the fridge: stems in a glass of water or wrapped in damp paper. Dries and freezes well.
History
Mint is ancient: Greeks and Romans already used it to flavour and cleanse. The genus name traces back to the nymph Minthe. Spearmint is the classic mint for mint sauce, tea and mojitos.
Nutrition
Low in calories, provides some vitamin A and C plus minerals; traditionally aids digestion.
Sources
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