Give Houseplants a Bath
Rinsing off houseplant foliage can keep both the dust and pesky insects at bay. Set pots in the shower for a few minutes or rinse them in the sink. With plants too heavy to move, wipe off the leaves with a damp cloth.
Mulch Before Snow
There's a window of opportunity for mulching because you want to wait until the ground freezes so you don't give rodents a hiding place too soon, but if you don't mulch before the snow accumulates, it won't get done. If we could rely on constant snow cover, mulching would be less necessary, but in the absence of that protection, we need to provide a winter blanket.
Set Out Water for Birds
If you keep birds around by feeding them, you should also provide water for them. The only realistic way to do that in winter is to use an electric birdbath heater that plugs into an outdoor outlet. They keep the water just above freezing and don't endanger the birds.
Save Evergreen Prunings
Save any leftover holiday greens or branches that you prune off your Christmas tree to lay around shrubs that need extra insulation, such as rhododendrons.
Cut Back Geraniums
If you brought in your Pelargonium geranium plants this fall and are growing them indoors this winter, chances are they've gotten very leggy by now. The cloudy, short days of November and December don't provide enough light for these plants to thrive. Cut back the plants to about 1 foot tall. They will resprout and grow bushier in the longer days of late winter.