USDA Zone 10b Vegetable Planting Calendar for December

March 22, 2026

December is one of the best months to be a gardener in USDA Zone 10b. While most of the country is putting gardens to bed, zone 10b growers are hitting their stride — planting cool-season vegetables, harvesting warm-season holdovers, and building out a full winter planting schedule that would make northern gardeners jealous.

This guide is your complete zone 10b vegetable planting calendar for December. Whether you’re in southern Florida, the Hawaii lowlands, or the frost-free stretches of coastal Southern California and the Rio Grande Valley, December gardening is active, productive, and genuinely exciting.

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What Is Zone 10b, and Why December Is Prime Growing Time

Zone 10b covers areas with average annual extreme minimum temperatures between 35°F and 40°F. In practical terms: you rarely see frost, and when you do, it’s a brief, anomalous event. The bigger challenge isn’t cold — it’s summer heat.

That flips the gardening calendar upside down. Your “cool season” is winter, and December sits right in the heart of it. Daytime highs typically run 70–80°F, nights dip into the 55–65°F range, and the combination is nearly perfect for leafy greens, root vegetables, and brassicas. The same crops that struggle in zone 10b’s brutal summer heat absolutely thrive in December.

If you’ve been coasting since October’s heat broke, now is the time to get serious. Use our free planting calendar to get dates customized to your exact zip code — especially useful if you’re in a microclimate that runs a bit warmer or cooler than the zone average.

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December Planting Schedule: What to Plant Now

Direct Sow Outdoors in December

These crops can go straight from seed to garden bed — no indoor starts needed.

Leafy Greens (peak season)

• Lettuce — All types: romaine, butterhead, looseleaf, crisphead. Succession-plant every 2–3 weeks for continuous harvest. Germination is fast at 65–70°F soil temperatures.
• Spinach — True baby spinach is possible now. Start harvesting outer leaves at 5–6 weeks.
• Arugula — Fast (30 days to harvest), prolific, and reseeds readily. Plant thickly and cut-and-come-again.
• Swiss chard — A zone 10b staple. Start now for January/February peak harvest.
• Mustard greens — High-yield, quick-growing, and thrives in December conditions.
• Kale — Lacinato/dinosaur kale is especially productive; harvest outer leaves to keep plants going.
• Collard greens — Extremely well-suited to zone 10b. December direct sow gives you 3–4 months of harvest.

Root Vegetables

• Radishes — Fast turnover (25–30 days). Plant a short row every 10 days for a steady supply.
• Carrots — Sow thickly in loose, deeply worked soil. ‘Nantes’ and ‘Chantenay’ types do well in warm-climate conditions. Expect 70–80 days to harvest.
• Beets — Both for roots and greens. ‘Detroit Dark Red’ and ‘Chioggia’ are reliable performers.
• Turnips — Often overlooked in zone 10b, but December is their sweet spot. Ready in 45–60 days.
• Kohlrabi — Plant now for February harvest. Unusual but productive.

Legumes

• Bush beans — Yes, in December. Zone 10b’s mild winter allows a late-season bean planting that wraps up before heat returns. Expect 50–55 days.
• Snow peas and snap peas — Cool weather is exactly what peas need. Provide a simple trellis and plant now for February–March harvest. This is one of the most reliable December wins in zone 10b.

Herbs

• Cilantro — Plant now and plant often. It bolts in heat, so December is a narrow but prime window.
• Dill — Same logic as cilantro. Multiple successions, 2 weeks apart.
• Parsley — Slow to establish but long-lasting. December starts will produce through spring.

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Transplant Starts in December

These crops are best started from transplants either purchased from a local nursery or started from seed 4–6 weeks earlier (October/November).

Brassicas (peak transplant time)

• Broccoli — One of December’s best performers in zone 10b. Transplant now for February–March heads.
• Cabbage — Set out transplants in early December for late-winter harvest.
• Cauliflower — Timing is tight; cauliflower needs consistent temperatures to head properly. Get transplants in early December.
• Bok choy — Fast-maturing (45–50 days from transplant), excellent stir-fry crop.
• Broccoli raab (rapini) — Prolific, cold-tolerant, and underused in zone 10b gardens.

Alliums

• Onion transplants or sets — December is the window. Short-day onion varieties are essential for zone 10b: ‘Granex’, ‘Texas Early Grano’, and ‘Burgundy’ are proven performers. Plant sets or transplants now for April–May harvest.
• Garlic — Plant cloves now (zone 10b garlic goes in late November through December). Soft-neck varieties perform better than hard-neck in warm climates.
• Green onions/scallions — Direct sow, harvest in 60 days.

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What to Keep Harvesting in December

If you planted in September or October, you may already be in harvest mode. Keep working these:

• Tomatoes — Fall-planted tomatoes often produce through December in zone 10b. Watch for overnight chill damage below 50°F on blossoms.
• Peppers — Warm-season peppers don’t die back in zone 10b winters. They slow down, but established plants will continue producing in mild weather.
• Eggplant — Same as peppers — established plants keep going. Don’t pull them yet.
• Sweet potatoes — If you planted in summer, December is often harvest time as vines begin to slow.
• Herbs — Basil may be winding down; shift focus to cool-season herbs like cilantro, parsley, and dill that are now starting up.

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Zone 10b December Planting Schedule: At a Glance

Week	What to Do
Week 1	Direct sow lettuce, arugula, radishes, cilantro; transplant broccoli, cabbage, onion sets
Week 2	Direct sow carrots, beets, spinach, peas; succession-sow radishes
Week 3	Direct sow bush beans, kale, chard, dill; transplant cauliflower, bok choy
Week 4	Succession lettuce and arugula; plant garlic if not already done; assess warm-season holdovers

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Winter Gardening Tips for Zone 10b

Irrigation matters more than cold protection. December in zone 10b is typically drier. Cool-season crops still need consistent moisture — wilting stress makes greens bitter and slows root development. Water deeply 2–3 times per week rather than shallow daily watering.

Mulch for soil temperature. Even though you’re not fighting frost, 2–3 inches of organic mulch regulates soil temperature swings and conserves moisture. This is especially important for carrots and beets, which crack in inconsistent soil conditions.

Watch for aphids on brassicas. Cool-season crops bring cool-season pests. Check the undersides of broccoli, kale, and cabbage leaves weekly. A strong spray of water dislodges most infestations before they establish.

Frost contingency plan. Zone 10b isn’t frost-free — it’s near-frost-free. When an unusual cold snap dips below 32°F, leafy greens and herbs are most vulnerable. Keep a roll of lightweight frost cloth handy. You won’t need it often, but December is one of the months where a rare frost is actually possible.

Succession planting is the zone 10b superpower. You have 3–4 months of productive cool-season growing. Don’t plant everything at once — stagger sowings of fast crops like lettuce, radishes, and arugula every 2–3 weeks for continuous harvest rather than a glut followed by a gap.

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Internal Links: More Zone Planting Resources

For zone-specific timing on seed starting, the Complete Seed Starting Guide covers when to start indoors for every zone — useful if you’re planning your January transplants now.

When your cool-season December plantings wrap up in late winter, the What to Plant in April by Zone guide will help you transition to warm-season crops — especially relevant for zone 10b, where the heat returns faster than anywhere else.

And for companion planting strategies that work in zone 10b’s year-round growing environment, the Companion Planting Guide for Vegetables covers which crops to grow together for pest control and yield benefits.

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Your Zone 10b December Planting Calendar Starts Here

December gardening in zone 10b is a genuine advantage — a second spring that most of the country can’t access. The key is not wasting it. Get cool-season crops in early December to maximize your growing window before March heat returns.

For your personalized zone 10b planting schedule with exact seed-starting and transplant dates based on your zip code, use our free planting calendar — it pulls your local frost data and builds a custom calendar for every crop you want to grow.

And if you want deeper guidance on warm-climate vegetable gardening — from soil prep to harvest storage — the Harvest Home Guides vegetable gardening series covers warm-climate growing in detail, with practical, zone-aware advice for year-round gardens like yours.

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Have questions about what’s working in your zone 10b December garden? The crops above are proven performers, but every microclimate is different — use the frost alert tool to track your local conditions and get notified of any rare cold snaps that might affect your winter garden.

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