Answer: Lavender plants can be difficult to overwinter successfully, especially in a location with heavy soil or in a spot that is anything except perfectly well drained.
Mulching would be limited to several inches of organic mulch spread over the root zone but not allowed to touch the stems. This mulch should be in place year round.
Some gardeners may add a layer of evergreen boughs laid lightly over top of the plants in midwinter, as well. This should be removed in early spring to promote air circulation.
Since they are somewhat woody, lavenders should not be pruned at all until very late spring. They may suffer some winter dieback but also leaf out late, so be very patient before pruning out any wood that is truly dead.
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