December To-Do List: Zone 4
- On a warm day, trim back and mulch perennials.
- Collect the seeds from pods and seedheads gathered earlier—wrap up some to give as holiday gifts.
- Check stored veggies—discard any with signs of spoilage.
- Continue harvesting greens from the hoop house or coldframe.
- Try growing salad greens and herbs in pots in a south-facing window.
- Take photos of your property to decide what needs changing before snow cover obscures your view.
December To-Do List: Zone 5
- Cover spinach and other overwintering crops with a row cover, and then top with 8 inches of straw.
- Make holiday decorations from holly and evergreen prunings.
- Wrap trees to protect them from deer and rabbits.
- Force some paperwhite narcissus bulbs: Put them in a bowl with pebbles and water, set the bowl in a bright cool window, then enjoy the show.
- Don't keep a live Christmas tree indoors for more than a week or two—plant it in the hole you dug last month.
- Inspect houseplants for insect pests; treat with insecticidal soap spray, if necessary.
- Use cut Christmas tree limbs to protect tender perennial beds.
December To-Do List: Zone 6
- As weather permits, continue to harvest leeks and kale.
- Keep straw snuggled around any crops still in the garden.
- If using a coldframe to grow greens through winter, rig a plastic tunnel over the frame for extra warmth.
- After the holidays, remove the branches from your cut Christmas tree and lay them over perennials and fall-planted pansies.
- Divide overgrown Boston ferns: Cut the rootball in half with a sharp knife, then repot.
- Cut back asparagus fronds.
- Refill bird feeders as needed.
December To-Do List: Zone 7
- Remember it's your last chance to gather leaves for mulching, composting, or digging into the soil.
- If weather is mild, feed pansies, snapdragons, and other winter flowers.
- Cover strawberries with a floating row cover—they'll fare better over winter and bear earlier next spring.
- Have row covers or burlap ready to protect camellias, Confederate jasmine, and fig trees, if temperature threatens to drop below 20ºF.
- Add a second layer of row cover to protect leafy vegetables, such as spinach, lettuce, and collards (remove the covers during the day, and they'll continue to produce).
- Place a few plastic jugs filled with water between rows to collect heat during the day and radiate it back at night.
- Plant bareroot trees.
December To-Do List: Zone 8
- Continue planting onions, chives, spinach, mustard, peas, beets, and radishes.
- Plant more lettuce in the coldframe.
- Plant petunias, calendulas, annual candytuft (Iberis umbellata), pansies, sweet alyssum (Lobularia maritima), cornflowers (Centaurea cyanus), stocks (Matthiola incana), scabiosa (Scabiosa atropurpurea), verbena, pinks (Dianthus spp.), and daisies.
- Plant bulbs, corms, and rhizomes of iris (Iris danfordiae, I. histrioides, I. reticulata), amaryllis, anemone (Anemone coronaria, A. sylvestris), calla, and liriope.
- Clean up garden debris to eliminate overwintering areas for diseases and insect pests.
- Start to build beds for spring by adding lots of compost.
- Plant bareroot trees, shrubs, roses, and vines.
December To-Do List: Zone 9
- Apply lime-sulfur spray to peaches and nectarines to combat peach leaf curl.
- Apply a dormant oil spray to fruit trees to kill insects and eggs.
- Sow winter cover crops, including annual rye grass (Lolium multiflorum), fava beans (Vicia faba), oats, barley, pearl millet (Pennisetum americanum), or proso millet (Panicum miliaceum).
- At month's end, plant perennials, shrubs, and trees.
- Also at the end of the month, begin to prune established deciduous trees and shrubs to remove crossed and diseased branches and to open up the center to light and air.
December To-Do List: Zone 10
- At the beginning of this month, start cold-loving veggies, such as Brussels sprouts and English peas.
- Most citrus fruits ripen now—remove and compost old fruit or use for slug traps.
- Feed mangoes a shot of compost tea as soon as flower spikes appear.
- If rainfall is scarce, provide at least 1 inch of water per week.
- If frost threatens, be prepared to protect plants with row covers.
- Keep harvesting beans, beets, broccoli, carrots, greens, onions, potatoes, radishes, and melons.