Leptospermum, also called tea tree, is a bush prized for its fine leaves and its many small star-shaped flowers, white, pink or red. Flowering usually occurs from May to July. In the garden, it thrives in sun in a light, free-draining, fairly poor soil, acidic to slightly calcareous, but can also be grown in a large pot or container. Resistant to sea spray, drought and pollution, Leptospermum is nevertheless fairly tender (down to around -6°C). In this guide we explain how to protect it in winter, whether you grow it in the ground or in a pot!
For full details on how to grow it, consult our complete sheet: "Tea tree, Leptospermum: plant, prune and maintain"
Leptospermum, a not very hardy bush
Leptospermum is an evergreen bush native to Australia and New Zealand. Fairly tender, it tolerates temperatures of about -5°C to -10°C depending on variety. However, growing conditions can affect its cold resistance: growing in a pot, exposure to wind or insufficient drainage do reduce plants' hardiness.
It is therefore important to choose the right site for Leptospermum before planting: place it in sun, in a sheltered spot, for example against a south-facing wall, and plant it in a free-draining, light growing medium. If necessary, mix some coarse sand and gravel into the planting soil.
How to protect a Leptospermum grown in the ground?
If you live in an area with a mild climate, such as the Mediterranean coast or the Atlantic coast, you can grow Leptospermum in the ground. We nevertheless advise protecting it:
- Ensure your Leptospermum is planted in a spot sheltered from wind. A sunny location during the day is ideal to keep warmth around the plant.
- Lay a good layer of mulch around the base of the bush to insulate its roots from cold. You can use dead leaves or straw, to a thickness of about ten centimetres.
- In case of severe frost, cover your Leptospermum with a winter fleece. Remember to ventilate from time to time by removing the fleece during mild daytime weather.
- Reduce watering in winter, as the plant has lower water needs. Excess moisture could cause roots to rot.
How to protect a Leptospermum grown in a pot?
Leptospermum grown in pots are more sensitive to cold, but can easily be moved to shelter.
- From November onwards, move the plant into an unheated greenhouse or a conservatory if possible, in a bright spot sheltered from frost. Temperature should not exceed 10°C.
- Check your Leptospermum regularly for any sign of stress or disease. Healthy leaves are a good indicator of plant health.
- You can put it back outside in spring, around May, once risk of frost has passed.
- If you cannot bring the pot under shelter, place a thick layer of mulch on the growing medium and wrap the pot with insulating materials such as bubble wrap, hessian or an old blanket. Also raise the pot off the ground, for example using wooden blocks, to help protect the roots from cold.
- Water sparingly. Wait until the surface of the potting mix is dry before watering again. To maintain humidity, mist the leaves regularly with water.
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