Here are a few tips on what to do and not to do to as the harsh winter weather approaches:
Bring in tropicals.
Boston ferns, tropical bananas, begonias, ficus, tender succulents like kalanchoe and jade trees, and any other houseplants that spent the warm seasons on the patio must be brought indoors pre-frost. Check for hitchhikers, and spray both sides of the leaves with insecticidal soap if you spot critters you’d rather not invite indoors. Water deeply with Thuricide solution if you suspect bugs are keeping house in the potting soil.
Once inside, position plants where they will receive indirect, bright light for at least five hours a day. Protect them from cold drafts, and mind the heating vents. Remember to place saucers or old plates underneath the pots to save your floors and tabletops. Water sparingly. Houseplants fare much better if kept on the dry side, especially in the winter when most are not actively growing.
Cover container gardens.
Anything planted in a pot above ground is more vulnerable to the effects of frost because the roots aren’t insulated underground.
Protect against frost damage to roots and trap any residual heat rising from the soil by covering all planted containers with frost cloth that goes all the way to the ground. Secure with something heavy so it doesn’t blow off.
Water.
Watering deeply before a freeze is beneficial in two ways: it provides valuable moisture that the plants won’t have access to should the ground freeze solid for an extended period; and, through evaporation, it helps raise the ambient air temperature immediately surrounding the plant. This rule applies to plants in the ground and in pots. The only exception is succulents. Keep them as dry as possible during cold weather, and protect them from snow and ice with a heavy cardboard box.
Post-Freeze:
Clean up the garden.
After the first hard freeze, herbaceous perennials (those that die to the ground and then reemerge in the spring) will all turn brown. Post-frost is the time to cut back perennials like upright Phlox, Baptisia, Amsonia, and Canna as well as hostas and non-evergreen ferns such as Athyrium nipponicum (Japanese painted fern).
Steer clear of silver and salvias.
In general, salvia and anything with silvery foliage (Artemisia, Buddleia, and Peroskia, for example) should be pruned in very late winter. Cut them back too early and you rob the plant of important insulation and stored sugars needed to feed it through the winter. Plus, these plants have hollow stems, and pruning exposes that inner tube to the elements. Once rainwater builds up inside, freezing temps can cause the stems to rupture. Keep these plants in good shape by pruning them at the beginning of March when the weather is beginning to warm up.
Go natural with grasses.
Just as your summer tan is starting to fade, ornamental grasses like Panicum (Panicum virgatum ‘Northwind’, right), Muhlenbergia, and Miscanthus are turning nice and bronzy. Leave these straw-hued beauties up throughout the season so birds can eat the seed and have a warm home for the night.
Plus, grasses cut too early are prone to rot at the growth point. Wait until late February to cut them back to just a few inches above the ground. This side-steps crown rot and avoids letting last year’s tan stems get tangled up in the fresh new green growth.
Postpone major pruning until mid- to late-January.
Pruning activates dormant buds in plants that aren’t in full hibernation. Cut pre-frost and the plant could push tender new growth that will get clobbered by freezing temps. Do your pruning in mid-winter when plants are fully dormant.
And don’t forget, frost isn’t all bad. It will shut down the mosquitoes, cabbage moths, and aphids that plagued us all fall, and it adds a touch of sweetness to kale and other winter greens. It also puts plants into full dormancy, giving them a chance to rest and rejuvenate for a fantastic spring show.
