Spider mites
Almost invisible without a hand lens. Pale yellow to red-orange specks on the underside of the silvery needle-like leaves. Container lavender baking in hot dry afternoon sun is the classic trigger. In-ground lavender is rarely affected.
Silver-grey foliage turns dull and dusty, then bronzes and crisps from the tips inward. Fine webbing strung between the woody stems and along leaf clusters in heavy infestations. Drought-stressed plants defoliate fastest. The plant can recover but often loses its compact shape for the season.
Hose down the foliage every 3 days for 2 weeks
Take container lavender outside or hold a hose nozzle 12 inches from in-ground plants. Spray cool water through the foliage and along the woody stems for 30 seconds. Mites can't reattach quickly when knocked off. Lavender's oily leaves shed water well and tolerate the rinse. Repeat every 3 days for 2 weeks. Water in the morning so foliage dries fast.
Move container lavender out of afternoon heat
Spider mites breed fastest on heat-stressed plants. Move pots into morning sun with afternoon shade for the rest of summer. Check soil moisture every 2 to 3 days because terracotta dries out fast and a wilting plant draws mites in.
Neem oil rinse, every 5 days for 3 rounds
Mix 2 tablespoons cold-pressed neem oil and 1 teaspoon dish soap per gallon of water.
Spray the underside of the foliage and into the woody stem joints in early evening, never in full sun on lavender's oily leaves.
Repeat every 5 days for 3 rounds to cover the egg-to-adult cycle.
