Here are some tips to help your shrubs and trees enter the coldest season in their best possible condition.
Late November/early December is a good time to give any perennials, shrubs, or trees planted this past growing season one last thorough soaking. Even though plants appear to be dormant, their roots are still growing and taking up water. Established evergreens would also benefit from a last watering. Evergreens, in particular, never get a reprieve from harsh drying winds and sun. Once the ground is frozen, their roots cannot take up water to replace what is lost through the leaves. It is important that evergreens of all types, but especially broadleaf evergreens like holly, rhododendron, azalea, and boxwood are well hydrated as they enter the winter season. Broadleaf evergreens have a larger leaf surface that is more prone to drying out especially in windy locations. Once the ground is frozen, their roots are not able to take up the water that is lost through the foliage. Watering now can minimize or even eliminate the unsightly browning that often occurs in winter with these species.
In very windy locations, it may be prudent to apply an anti-transpirant such as Wilt-Pruf to your evergreens. An anti-transpirant will coat the shrub’s leaves providing protection against drying winds. A burlap screen erected around your plants will also be effective.
Shallow rooted plants such as perennials, roses, and azaleas will benefit from having an extra layer of mulch applied after the ground has frozen. This mulch is applied to keep the ground from thawing and then refreezing. The thaw/freeze cycle causes plants’ roots to tear and heave out of the ground leaving them exposed to drying winds. This extra mulch can be in the form of bark products, oak leaves, straw, evergreen boughs, etc. Don’t use anything that will get mushy and smother the crown of the plants. Remove the extra mulch by the end of March. Periodically throughout the winter and especially after a thaw/freeze cycle, check roots for heaving. Lightly tamp back in place.