December Garden Checklist: Indoor and Planning

December is the shortest, quietest month in the garden — and the one that separates organized gardeners from everyone else. The ground is frozen or nearly so, the harvest is over, and the temptation is to close the door until March. But December is full of small tasks that make spring dramatically easier: seed orders, indoor starting, tool care, and planning. None of it is urgent, all of it is useful, and it is the perfect work for short days and long evenings.

What You Will Need

• Grow light and trays if you plan to start seeds indoors
• Seed catalogs and your garden journal
• Compost bin or pile — still working through the cold
• Tool-cleaning supplies: wire brush, sharpening stone, oil
• Graph paper and a pencil for the garden map
• Milk jugs or containers if you want to try winter sowing

Step 1: Set Up an Indoor Seed-Starting Corner

December is the month to build your indoor seed-starting setup, before February makes it urgent. You do not need a greenhouse — a table, a shop light or LED grow light, and a tray system are enough for most home gardens. Position the light two to four inches above the seedlings and run it 14 to 16 hours a day on a timer. If you are new to starting seeds, our how-to-start guide covers the basics of light, moisture, and timing.

Step 2: Try Winter Sowing for Hardy Crops

Winter sowing is the December superpower: plant hardy seeds in repurposed milk jugs or covered containers, set them outside, and let snow, cold, and sunshine handle the stratification. Native wildflowers, hardy annuals, and cool-season vegetables like kale and spinach germinate naturally in spring, completely skipping the indoor setup. It is almost zero-effort, requires no lights, and produces tough, well-acclimated seedlings. Cut the jugs, add drainage holes, sow the seeds, tape the jugs shut, and wait.

Step 3: Order Seeds and Supplies Early

If you did not order in November, do it now. Popular varieties — especially new releases and tried-and-true heirlooms — sell out by late winter, and shipping slows down in January. Order seeds, seed trays, potting mix, and grow lights while the selection is full. December orders also arrive before the spring rush, so you can do a germination test at your leisure instead of at planting panic time.

Step 4: Keep Compost Working Through the Cold

A compost pile does not stop in December; it just slows down. Keep adding kitchen scraps, and mix in browns — shredded cardboard, dry leaves, paper — to balance the winter wet. If your pile is frozen solid, do not fight it; let it rest, and turn it when it thaws. A pile that stays roughly balanced through winter breaks down faster in the first warm weeks of spring. Our greens vs. browns guide is the reference for keeping the mix right.

Step 5: Review Notes and Sketch the Garden Map

Pull out your garden journal from this season and read it while the memories are still accurate: which varieties thrived, which disappointed, where the pests hit, which beds stayed soggy. Then sketch next year’s map — crop rotations, new beds, trellis locations, and the succession plan. This hour in December saves hours of confusion in April, and it is the difference between a garden you manage and one that manages you.

Step 6: Sharpen and Oil Your Tools

December is tool-maintenance month. Scrub off caked soil, remove rust with a wire brush, sharpen hoes, shovels, and pruners with a file or sharpening stone, and wipe wooden handles with linseed oil. Lubricate the moving parts of pruners and loppers. Sharp tools cut cleaner, work easier, and stress plants less — and a properly stored tool lasts decades instead of seasons.

December is also the month to treat your compost pile like a winter patient rather than an afterthought. If you have a tumbler, give it a spin every couple of weeks to keep air moving even when it is cold; if you have an open pile, throw a tarp or old carpet over the top to keep winter rain from saturating it into a soggy, oxygen-starved mass. Stockpile browns — dry leaves, shredded cardboard, and paper — near the pile now, so you can balance the winter’s kitchen scraps without trudging around the yard in January. Piles that go into spring balanced and damp-but-not-soggy break down in weeks, not months, and deliver finished compost exactly when the new beds need it. While you are in the yard on mild days, also give perennials one last check: push back any that frost heaving has lifted, and make sure snow sliding off roofs is not burying shrubs in crushing piles. December chores are small, but they are the difference between a garden that emerges from winter intact and one that needs repairs before it can grow again.

FAQ

Do I need a grow light to start seeds in December?

For winter sowing outdoors, no — nature handles it. For indoor starting, yes: a basic LED shop light works, positioned just inches above the seedlings. Windowsill light alone makes seedlings stretch and flop, especially in winter’s low sun.

What seeds can I start indoors in December?

Very few — December is mostly for planning and ordering. Onions and leeks can start in late December or January in many zones, and peppers in late January or February. Check your last frost date and count back the weeks each crop needs before transplanting.

Is it okay to keep adding to the compost pile in winter?

Absolutely. Keep adding kitchen scraps and browns in roughly balanced layers. The pile will slow down or freeze, but it will restart quickly in spring. Avoid adding meat, dairy, or diseased plants regardless of season.

Bottom Line

December is the thinking month: order seeds, set up the light, try winter sowing, keep the compost balanced, review the notes, and sharpen the tools. None of it is heavy labor, and all of it compounds into a spring that starts fast. The garden is resting — you get to be busy in the best way.

As an Amazon Associate, I earn from qualifying purchases.