Why Did Frost Damage My Lavender Plant?

Frost damage on lavender typically manifests in one of two ways: either the soft new growth that emerged in early spring is blackened and wilted after a late frost, or an established plant develops split or cracked stems after a particularly severe freeze. Understanding which type of damage has occurred determines how to respond and how much lasting harm has been done. In most cases, frost damage to otherwise healthy lavender in a suitable climate is recoverable and does not kill the whole plant, but it does require prompt action to prevent secondary infection through the damaged tissue.

Spring frost on new growth

Lavender often begins putting on soft new growth in late February or March during mild spells, and this tender growth is highly vulnerable to a hard frost that arrives in April or even May. Affected shoots turn black and limp within 24 hours of a frost event. This damage, while dramatic-looking, is usually limited to the current season's new tips and does not affect the older, more frost-hardened wood beneath. Wait for warmer, settled weather, then cut the blackened growth back to healthy, firm wood below the damaged zone.

Stem splitting from severe freeze

In a very hard or prolonged freeze, ice crystals forming inside the woody stems can physically rupture the cell walls, causing the bark to split longitudinally. This creates open wounds through which fungal pathogens — particularly Phomopsis, the shab disease organism — can enter. Any split stem should be assessed: if the split is superficial and the wood beneath is healthy, wrap the stem lightly with biodegradable grafting tape and it may callus over. Deep splits that have exposed a significant length of interior wood are best removed to prevent disease entry.

The wait-and-see approach

After a damaging winter or late frost, resist the urge to immediately cut back the whole plant. Lavender can look entirely dead in early spring and still recover from basal buds. Leave the plant until late April, check for green tissue by scratching stems at multiple points, and then prune selectively back to the highest living growth. Premature pruning sometimes removes the only viable growing points.

Protecting lavender before frost

A layer of horticultural fleece thrown over the plant on nights when a hard frost is forecast provides significant protection for soft spring growth. Remove it during the day so the plant receives light and airflow. Mulching around the base with grit or bark insulates the root zone against penetrating cold in autumn, which is often more damaging than brief surface frosts.

Frost-tender varieties

French lavender (L. stoechas) and related species with butterfly bracts are significantly less frost-tolerant than English lavenders. Move container specimens under glass or into a frost-free porch before the first autumn frosts and keep them there until the risk of hard frost has passed in late spring.