What's Wrong with My English Lavender?

English Lavender evolved on the rocky, fast-draining hillsides of the Mediterranean where the roots never sit in standing water. Heavy clay, a wet winter, or a warm humid summer all lead to the same end. The roots suffocate and a soil-borne water mold moves in, and the plant can look fine right up until it collapses. The base of the stems often turns dark and soft at the crown once the rot reaches that far.

Lavender's fine, shallow roots need air between waterings. When the soil stays damp, the roots stop functioning and the plant pulls back from the oldest stems first, turning them yellow. Clay soil is a common trigger even with careful watering because it never drains fast enough.

Lavender naturally sheds old foliage from the woody interior of the plant as new growth pushes out from the tips. If the yellowing is concentrated deep inside the canopy on the oldest wood and the stem tips look silver-green and healthy, this is normal turnover, not a watering problem.

English Lavender blooms on the energy it gathers from full sun. In a spot with less than six hours of direct sun daily, the plant stays green but puts almost nothing into flower production. Even partial shade from a nearby fence or tree can cut the bloom significantly.

Lavender blooms on new wood. Without annual pruning right after flowering, the plant becomes increasingly woody at the base and puts less and less energy into producing fresh flower-bearing stems. An unpruned lavender that is a few years old often looks large but blooms sparsely.

A newly planted lavender spends its first growing season building roots rather than flowers. Sparse or no blooms in the first year are normal and are not a sign that anything is wrong.

English Lavender is a subshrub that naturally converts its lower stems to hard, brown wood each year. Without pruning, the green flower-bearing zone retreats higher and higher up the plant until the center is a mass of dead wood with a sparse tuft of growth on top. This is the most common reason lavenders look ugly after a few years.

Botrytis is a gray fuzzy mold that attacks lavender flower spikes and stems in wet, humid weather, especially when airflow is poor. The disease colonizes spent flowers and moves into stems if the conditions stay wet. Lavender's dense, upright flower spikes trap moisture and create the damp surface Botrytis needs to spread.

Soft, pale green or gray aphids cluster on lavender's new shoot tips and emerging flower buds, sucking sap and curling the tender growth. Lavender's aromatic oils repel many insects but do not deter aphids, which target the non-aromatic new tissue before the oils concentrate in mature stems.