Why did my lavender die over winter?

Lavender is hardy to well below the temperatures a British winter produces, so cold on its own rarely kills English lavender. What kills it is weeks of cold, saturated soil around the roots and crown, which is precisely what a wet winter on clay delivers. Understanding that changes what you do about it entirely — the answer is drainage, not protection.

Step by step

1. Wait until May before writing the plant off.Lavender looks dead in March in a normal year. Scratch a stem with a thumbnail: green underneath means it is alive. Give it until growth is properly underway before removing anything.
2. Look at the base of the plant.Blackened, soft or slimy stems at ground level, and a crown that comes away when you pull gently, mean rot. Grey, brittle, dry stems that snap cleanly mean the plant has died back rather than rotted, which points more towards cold or old age.
3. Assess the drainage honestly.Does water sit on the surface after rain? Is the soil heavy clay? Was the plant in a low spot or at the bottom of a slope? If the answer to any of these is yes, that is almost certainly your cause.
4. Check what was mulched around it.A thick compost or bark mulch heaped against the stems holds moisture at exactly the point where the plant is most vulnerable. Gravel or grit is the correct mulch for lavender, and it should be kept slightly clear of the stems themselves.
5. Consider whether it was the wrong species.Lavandula stoechas, the one with the ear-like petals, is considerably less hardy than English lavender and is the type most often lost over winter. If your plant had ears, the species is a large part of the answer.
6. Check whether it was cut back in autumn.Cutting lavender hard in autumn provokes soft growth that cannot harden before the cold and leaves fresh wounds through the wet months. The main cut belongs in August, after flowering.
7. Replant on a mound.Raise the planting position 100 to 150mm above the surrounding soil, work grit through the planting area, and set the plant so water runs away from the crown. On heavy clay this is the single most effective change available.
8. Or move it to a pot or a raised bed.On genuinely wet ground, growing lavender in a large container of gritty compost, or in a raised bed, works far better than fighting the soil. Make sure the pot drains freely and stands on feet through the winter.
9. Give it full sun and stop feeding it.Shade and rich feeding both produce soft growth that is much less able to come through a wet winter. Poor, dry, sunny and unfed is what lavender wants.
10. Take cuttings each summer as insurance.Lavender roots very easily from semi-ripe cuttings taken in summer. Three or four rooted cuttings in a cold frame means a lost plant costs you nothing.

Tips

• Lavender is a short-lived plant. Eight to ten years is a good life even for a well-grown one, and a plant that dies at that age has not necessarily been mistreated.
• A row of lavender where the plants at the low end of the run died and the ones at the top survived is a drainage diagnosis by itself.
• Snow is not the problem — it insulates. It is standing water and saturated ground for weeks that kills.
• Do not attempt to save a rotted plant by cutting it back. There are no dormant buds in the bare wood and the crown is already gone.

Common mistakes

• Mulching lavender with compost or bark — It holds moisture against the crown all winter, which is exactly the condition that rots the plant. Use grit or gravel.
• Cutting it back hard in autumn to tidy the border — It provokes soft growth at the worst possible time and opens wounds through the wet season.
• Assuming the winter was unusually cold — English lavender tolerates far lower temperatures than a British winter produces. Wet is the killer in almost every case.
• Replanting a new lavender in exactly the same spot with no change — The same conditions produce the same result. Improve the drainage or move the plant.

Questions people ask