December Gardening Tips
Give Them a Bath: If you notice a layer of dust on your houseplant leaves, wash small plants in the sink and wash larger ones in the shower. Use room-temperature water to avoid damaging the leaves.
Note: Regularly washing leaves can help prevent some insect pests such as spider mites.
In the South
Water Garden Beds: If you live in a frost-free climate, don't forget to water garden and landscape beds during dry spells. December often marks the start of the dry season.
Protect Tender Plants from Frost: If frost threatens tender or tropical plants, move them indoors or cover them with a sheet or blanket overnight. Don't use plastic; the plastic may get cold enough to cause cold damage where it touches plant leaves.
Note: Cool-season, frost-hardy plants such as dianthus, snapdragon, kale,and pansies easily survive dips below frost. You don't need to worry about covering tough beauties like these!
Attack Cool-Season Weeds: While summer weeds may be done, there's a new crop of winter weeds ready to sprout. Hand pull weeds before they get large enough to set seeds and apply a thick layer of mulch to keep weed seeds from sprouting.
Get more tips for attacking weeds.
In the North
Deal with Ice: Once winter snows arrive (if they haven't already), use sand or plant-/pet-friendly ice-melting products to keep walkways safe for you and your garden plants. Avoid using products that contain salt (sodium chloride) or calcium chloride; over time, these chemicals can build up in the soil and harm your plants.
Mulch Garden Beds: If you want to apply a winter mulch and the soil is frozen in your area, it's safe to apply several inches of winter mulch. It's best to wait until the soil is frozen; the real value of mulch is that it keeps the soil consistently cold all winter long so your plants don't start to wake up (or heave up) on warm-winter days.
Plant Bulbs: If the soil hasn't frozen in your area, you can still get spring-blooming bulbs such as tulips and daffodils planted in your garden. As long as you can dig a hole, it's all right to plant bulbs. If the soil has frozen, plant bulbs in pots and keep them in a cold place, such as an unheated garage or attic, for the winter. In February, you can bring them to warmer temperatures and force the bulbs to bring a little cheer in late winter.