December Gardening: More Possible Than You Think
December feels like an off-month for most gardeners, but that depends on where you live. In mild climates, it’s one of the best times of year to grow greens, roots, and brassicas without battling summer heat or pests.
Even if you’re in a cold zone with frozen ground, December isn’t wasted time. Starting seeds indoors, planning beds, and ordering seeds are all productive steps that set you up for a strong spring.
This guide breaks things down by zone group so you can find your situation quickly and know exactly what to do this month.
Zones 3–5: Focus on Indoor Seed Starting and Planning
If you’re in zones 3, 4, or 5, December means cold — often very cold. Outdoor planting isn’t on the table, but that doesn’t mean you stop gardening.
This is a great month to start slow-growing crops under grow lights if you have a long lead time before your last frost. Onions, leeks, and celery all benefit from an early start indoors in December or January.
| Zone | Outdoor Planting | Start Indoors |
|---|---|---|
| 3a / 3b | Not recommended | Onions, leeks (late December) |
| 4a / 4b | Not recommended | Onions, leeks, celery |
| 5a / 5b | Not recommended | Onions, leeks, celery |
If you’re in zone 5 with a cold frame or low tunnel, you may be able to keep established overwintering crops like spinach or mâche alive — but December isn’t the time to start new ones outdoors.
Use this month to order seeds, organize your planting calendar, and check your grow light setup. A little prep now makes February and March much less stressful.
Zones 6–7: Cold Frames Open the Door
Zones 6 and 7 sit in that in-between space — too cold for open-air planting, but manageable with some protection. December is quieter outdoors, but not entirely inactive.
Gardeners with cold frames or low tunnels can maintain hardy overwintering crops planted in fall. Spinach, kale, claytonia, and mâche can survive and even slowly grow under cover in these zones.
| Zone | Outdoor (with protection) | Start Indoors |
|---|---|---|
| 6a / 6b | Maintain existing cold frame crops | Onions, leeks, celery (late Dec) |
| 7a / 7b | Hardy greens under cover; garlic mulching | Onions, leeks, celery |
Direct sowing new crops outdoors in December in zones 6–7 is generally not effective — germination is too slow and unreliable. Focus on protecting what’s already in the ground and starting long-lead crops indoors under lights.
Zones 8–9: Real Outdoor Planting Starts Here
This is where December gardening gets genuinely exciting. Zones 8 and 9 have mild enough winters to grow a solid range of cool-season vegetables right in the ground.
Frost is possible, especially in zone 8, but most cool-season crops handle it well. You can direct sow many things and transplant others started a few weeks earlier.
| Zone | Direct Sow Outdoors | Transplant Outdoors | Start Indoors |
|---|---|---|---|
| 8a / 8b | Spinach, lettuce, radishes, arugula, carrots, beets, peas | Broccoli, cabbage, kale starts | Tomatoes, peppers (late Dec for early spring) |
| 9a / 9b | Lettuce, spinach, carrots, beets, radishes, turnips, peas, cilantro, chard | Broccoli, cauliflower, cabbage, onion transplants | Tomatoes, peppers |
Zone 8 gardeners should keep row cover on hand for frost nights. Zone 9 is reliable enough that most cool-season crops will grow steadily through winter without much intervention.
Zones 10–11: Year-Round Growing Season
In zones 10 and 11, December is a productive month — sometimes one of the most comfortable for gardening, since the intense summer heat has passed. Cool-season crops thrive in these mild winter conditions.
You can plant a wide variety of vegetables directly in the ground this month. The key is knowing which crops prefer cooler temps and which ones need a bit more warmth to thrive.
| Zone | Direct Sow Outdoors | Notes |
|---|---|---|
| 10a / 10b | Lettuce, spinach, kale, chard, carrots, beets, radishes, peas, beans, cucumbers, squash | Warm-season crops possible in 10b with monitoring |
| 11a and above | Most vegetables year-round; tomatoes, peppers, beans, greens, root vegetables | Watch for heat if temperatures spike |
If you’re in zone 10 or 11, check out the detailed seed starting guides for zone 10b and zone 11a for month-by-month planting breakdowns specific to your area.
What to Plant in December: A Crop Quick-Reference
Some crops come up again and again across multiple zones in December. Here’s a quick look at the most common ones and where they fit.
- Lettuce: Best in zones 8–11 outdoors; start indoors in zones 6–7 under lights
- Spinach: Hardy enough for zones 7–11 outdoors with some protection in zone 7
- Carrots: Direct sow in zones 8–11; soil must be workable and not frozen
- Beets: Good for zones 8–11 in December
- Onions: Start from seed indoors in all zones; transplants go out in zones 8–11
- Peas: Direct sow in zones 8–11; earlier than most gardeners expect
- Broccoli and cabbage: Transplant established starts in zones 8–11
- Garlic: Can still go in the ground in zones 7–10 in early December
Indoor Seed Starting in December: What’s Worth the Effort
Even in cold zones, December indoor seed starting makes sense for certain slow-growing crops. The goal is to have transplants ready to go out as soon as your soil is workable in spring.
Onions and leeks have a long growing season and benefit from an early start — even in January or February they’re not too early. Starting them in late December in zones 3–6 is reasonable if you have good light.
Celery and celeriac are also candidates for a December indoor start in colder zones — they need a long lead time and don’t transplant well if rushed. Keep expectations realistic about germination speed in cool indoor environments.
Frequently Asked Questions
Can I plant vegetables outside in December?
Yes, if you’re in zones 8–11. Cool-season crops like lettuce, spinach, carrots, and beets can be direct sown outdoors in mild winter climates. In colder zones, outdoor planting in December isn’t practical without heavy protection infrastructure already in place.
What can I start indoors in December?
Onions, leeks, and celery are the most common crops to start indoors in December across all zones. Gardeners in zones 8 and warmer can also start tomatoes and peppers indoors in late December for early spring transplanting.
Is it too late to plant garlic in December?
In zones 7–10, early December is still a workable window for garlic. The cloves need time to establish roots before a hard freeze, but not top growth. In zones 3–6, December is generally too late unless the ground is still workable and a hard freeze hasn’t hit.
What should I do in the garden in December if I can’t plant anything?
Order seeds for the coming season, clean and organize tools, test your grow light setup, and map out your spring beds. Cold-zone gardeners often get a head start on the season simply by being prepared before February rolls around.
Do I need a grow light to start seeds indoors in December?
For most crops, yes. A sunny south-facing window rarely provides enough light intensity during the short days of December. A basic LED grow light on a timer will give you much better germination and stockier seedlings than a windowsill alone.
Free tools for every gardener
Stop guessing. Start growing with confidence.
Whether you’re a seasoned grower or just getting started, mysimpleseed has you covered — from timely email alerts for your zip code to a personalized beginner plan built around your space and budget.
Gardening Alerts
Get email reminders for seed starting, sowing, transplanting, watering, and harvesting — timed to your exact location.
Free Beginner Plan
Enter your zip code, space, and budget. We’ll pick 2–4 easy crops and send you personalized alerts to grow them successfully.