How do you harvest and keep English lavender over winter?
Temperature and watering
In the northern half of the US, lavender is pruned in spring if your plant is in the ground. Growth that will be trimmed off in spring, provide an extra measure of winter protection for cold climates. In late fall, cover the plants loosely with chopped leaves or straw in zones 5 and 6. For lavender in containers, pruning/harvesting leaves can be done in fall. Either store them at 40 F. and water sparingly or bring indoors to a sunny window. Flowers are harvested early in the day just as they start to open. https://www.gardeningknowhow.com/edible/herbs/lavender/growing-lavender-in-pots.htm