Now is the time for attention to shrubs such as Azalea, Rhododendron, Holly, and Boxwood, according to an article in the “Gardening Gazette” of Cornell Cooperative Extension of Livingston County.
If these plants have been mulched with peat moss or any other medium, they may not develop mature stem tissue where they are in contact with the mulch. Serious injury can follow an early frost. This is especially true if the plantings are in low areas or frost pockets.
For these plants to become sufficiently hardened to withstand early frost damage, move the mulch material two to three inches away from the base of the stems in mid-August. This will allow time for the bark and wood of the plant to dry and mature before early fall frost can cause injury.
Replace the mulch around the basal stems in the autumn after leaves fall from the trees, and add new mulch to maintain a three-inch layer throughout the planting.