Zone 10 Winter Planting Guide: What to Grow December Through February

December through February is the payoff season in Zone 10. Everything planted in October is now producing — broccoli and cauliflower are heading up, carrots are sweetening in the cool soil, peas are filling pods, and the tomato plants that went in on October 1 are bearing their heaviest crops of the year. While gardeners in Zone 5 through Zone 8 are reading seed catalogs indoors and waiting for spring, Zone 10 gardeners are standing in the most diverse and productive garden of their year.

Zone 10 winters are mild and frost-free almost every year. Miami averages daily highs of 75–78°F in December and 72–75°F in January; San Diego coastal averages 65–68°F. These temperatures are perfectly suited to the full range of cool-season vegetables, and they produce a quality advantage that northern gardens simply cannot replicate. Carrots harvested in January from Zone 10 soil are noticeably sweeter than summer-harvested carrots — cold soil temperatures convert starches to sugars in the same way that frost improves Brussels sprouts in Zone 6. Broccoli heads formed in cool December air are tighter, denser, and more flavorful than heat-rushed spring broccoli. Winter is when Zone 10 produces its best food.

The winter strategy is straightforward: keep harvesting, keep succession sowing fast crops, manage the rare frost event, and start the next season's onions and late-winter potatoes. This guide covers all of it.

Zone 10 Winter at a Glance

December: Peak Harvest Begins

December is the month when the garden planted in October reaches full production. Nearly every crop planted in October is harvestable by December, and the cool temperatures produce the best quality of the year.

December Harvest Lineup

Tomatoes in December: The tomatoes transplanted in October are actively fruiting by December. This is the start of their peak production window — cool nights (60–68°F) and warm days (72–80°F) are ideal for fruit set, flavor development, and consistent production. Expect 3–5 lbs per plant per week from established plants at this stage.

What to Keep Planting: December Succession Sowing

Winter in Zone 10 is a continuous planting and harvesting system. As you harvest beds, resow with the next succession. Fast crops (radishes, arugula, Asian greens) can complete 3–4 cycles between December and March.

December Timing Detail Table

January: Sweetest Harvests and Frost Readiness

January is when Zone 10's cool-season garden reaches its flavor peak. Carrots that have been growing since October now have 3+ months of cool soil development and are noticeably sweeter and crisper than anything harvested in warmer months. January beets are deeper in color and more tender. January broccoli heads are the tightest and most flavorful of the season.

January Harvest: Carrots at Their Best

Carrots in Zone 10 perform dramatically better in winter than in any other season. Germinated in October when soils were still 70–75°F, they spend their development months in cooling soil, and by January the combination of 55–62°F soil temperatures and cool air has converted maximum starch to sugar. Nantes-type carrots are at peak flavor and texture from January through early March — harvest as needed rather than all at once.

January: Start Onion Seeds Indoors

January is the time to start onion seeds indoors for transplanting in February and March.

Short-day onions only in Zone 10. Onion bulb formation is triggered by day length. Long-day varieties (common in northern zones) require 14–16 hours of daylight to form bulbs; Zone 10's winter days are only 10–11 hours long. Short-day onions form bulbs at 10–12 hours of daylight and are the correct choice for Zone 10. Granex 33 (the commercial base for Vidalia onions) and Walla Walla are the most reliable short-day performers [University of Florida IFAS, 2024].

January Frost Management

Zone 10 frost is rare but real. Miami has experienced killing frosts in January in events like the January 2010 cold snap (lows of 34–36°F in Miami-Dade County, 28–32°F in Homestead). Coachella Valley experiences January frost more regularly, with lows reaching 28–32°F in some years. San Diego coastal locations rarely see frost but inland valleys can freeze.

Frost action plan for Zone 10:

1. Monitor extended forecasts daily from December through February
2. When overnight lows below 35°F are forecast, act the evening before:
   • Drape 1.5–2 oz floating row cover directly over tomatoes, peppers, eggplant, and tender greens
   • Cover citrus and young tropical fruit trees with burlap or frost blankets
   • Leave row cover in place until temperatures climb above 40°F the following morning
3. Do not use plastic sheeting alone — plastic transmits cold rather than trapping heat
4. Water the soil thoroughly the day before a frost: moist soil retains heat much better than dry soil and can raise canopy temperature by 2–4°F overnight

Most Zone 10 winter vegetables — broccoli, cabbage, kale, peas, carrots, beets — will tolerate a light frost (28–32°F) without damage. Tomatoes, peppers, and eggplant are frost-sensitive; protect these first.

February: Completing the Winter Cycle and Starting Spring

February is the bridge month in Zone 10. The cool-season garden continues at full production — February broccoli, January carrots, peas, and winter greens are all still active. Simultaneously, February is when you begin the spring transition: potatoes go in the ground, more lettuce successions get sowed, and the end of the cool season comes into view.

February: Direct Sow Potatoes

February is the prime potato planting month in Zone 10. Potatoes planted February 1–28 produce tubers from late April through May — ahead of summer heat that would otherwise cause tubers to go soft or develop heat damage.

February Timing Detail Table

Miami vs. San Diego for February carrots: San Diego coastal gardeners can continue succession sowing carrots through late February with confidence — soil temperatures remain below 68°F into March, and cool marine air prevents rapid bolting. Miami gardeners should complete their final carrot sowing by February 15; Miami daytime temperatures begin rising noticeably by late February, and carrots sowed after mid-February will mature in April heat with reduced quality.

February: Transition Broccoli and Cauliflower Out

Broccoli and cauliflower planted in November will be finishing their main head harvest in February. After cutting the central head, leave plants in place — side shoots (sometimes called "raab" or secondary florets) continue to develop on broccoli plants for 4–6 additional weeks. A Belstar or Calabrese broccoli plant cut in January may produce side shoots through March, extending the harvest considerably.

Citrus harvest peak (December–March)

Zone 10 winter is also the peak of citrus season. Navel oranges (November–January), Valencia oranges (March–June), grapefruit (October–April), and mandarins / tangerines (November–February) all peak in Zone 10 winter. Lemons produce year-round with the heaviest crop November through April. Key care: reduce irrigation slightly as fruit matures to concentrate sugars; apply a citrus-specific fertilizer in February to fuel the spring flush.

Month-by-Month Summary: Zone 10 Winter

Variety Recommendations for Zone 10 Winter

Soil Prep and Compost in Zone 10 Winter

Zone 10 winter reveals a fundamental truth about gardening in the subtropics: organic matter does not last. Soil that was heavily amended in October has lost 40–60% of that organic matter to microbial activity by January — even in the cooler winter months. This is 2–3 times faster than the decomposition rate in Zone 6–7 soils [University of Florida IFAS, 2023].

The practical implication: apply 1 inch of finished compost to active beds every 6–8 weeks through winter, not just at the start of the season. This is not a northern-zone practice — in northern climates, a single fall compost application is largely sufficient because cold temperatures slow decomposition and the garden is dormant. In Zone 10, a winter garden is at maximum production while soil biology remains active all year. Feeding it monthly is not optional.

Winter compost application schedule:

Why this matters for compost sourcing: A Zone 10 gardener running active beds year-round applies approximately 6–8 inches of compost annually across those beds — versus the 2–3 inches a northern gardener might apply in spring. Purchasing bagged compost for this volume becomes expensive quickly. Producing your own compost continuously from kitchen scraps is the most cost-effective solution.

Home composting equipment like the Reencle countertop composter processes food scraps year-round — including all the citrus peels, avocado skins, vegetable trimmings, and tropical fruit waste that Zone 10 kitchens generate heavily in winter — and produces compost-in-progress that feeds directly back into the 6–8 week topdress cycle. This closed loop is especially practical in Zone 10, where the demand for compost never pauses. For more on the composting cycle that keeps Zone 10 soil productive, see our complete guide to using compost in vegetable beds.

Pest and Disease Watch: Zone 10 Winter

Winter pest pressure is lower than fall and spring, but several pests remain active year-round in Zone 10's mild climate.

Cabbage loopers (ongoing through winter) The white moths that began laying eggs on brassicas in October continue through the mild Zone 10 winter. There is no cold event to break the cycle. Apply Bt spray to all broccoli, cauliflower, and cabbage foliage every 10–14 days through February. Check for egg clusters (white, ribbed, oval eggs laid singly on leaf undersides) at every garden visit and crush them before they hatch.

Aphids on greens and peas (December–February) Aphid populations build steadily on lettuce, peas, kale, and broccoli through winter in Zone 10's mild temperatures. Weekly inspection and water-spray removal is sufficient for light infestations. Insecticidal soap or neem oil applied to undersides of leaves handles heavier pressure. Encouraging beneficial insects (ladybugs, lacewings) by planting flowering herbs (dill, fennel, cilantro) nearby provides natural long-term aphid control.

Slugs and snails (December–January, especially Miami wet winters) Cool, moist December and January conditions favor slug and snail activity. They eat large irregular holes in lettuce and spinach, and chew through seedlings at night. Apply iron phosphate bait (Sluggo) around vulnerable beds — it is non-toxic to pets and wildlife and remains effective after rain. Avoid copper tape around containers, which quickly oxidizes in Zone 10 humidity and loses effectiveness.

Tomato hornworm (January–February) As tomatoes continue producing through winter, hornworm caterpillars can appear on warm January and February days when adult moths are active. The caterpillars are large (3–4 inches) and green with white diagonal stripes — they blend into foliage but cause rapid defoliation. Hand-pick and drop into soapy water; apply Bt as a preventive.

Season Extension and Heat Protection Tips

Frost protection: the practical kit for Zone 10

Every Zone 10 gardener should have these three items in the garden shed from November through February:

1. 1.5–2 oz floating row cover — enough to cover tomatoes, peppers, and eggplant in a 4×8 raised bed. Store folded and accessible.
2. Frost blankets for citrus — a large burlap piece or purpose-made frost blanket for young citrus or tropical fruit trees
3. Extra garden stakes — to tent row cover above plants rather than laying it directly on foliage, which can cause bruising on soft tomato foliage at 28–30°F

The warm-soil moisture trick: Water garden beds thoroughly the day before any forecast freeze. Moist soil has 3–4 times the heat capacity of dry soil and releases heat slowly overnight, raising canopy air temperatures by 2–5°F above what dry soil would produce [UC Cooperative Extension San Diego, 2022].

Cold-tolerant winter crops need no protection: Kale, chard, broccoli, cabbage, carrots, beets, peas, and spinach all tolerate Zone 10's rare frost events without damage. Save your row cover for frost-sensitive crops.

Composting This Season

Winter kitchen scraps in Zone 10 are nutritionally rich: citrus peels, avocado skins, root vegetable trimmings, leafy green stems, and winter squash skins all compost quickly at Zone 10's mild temperatures. Unlike in northern climates where winter composting slows dramatically in a cold outdoor pile, Zone 10's 60–70°F December–February temperatures keep outdoor piles moderately active.

Outdoor pile management in Zone 10 winter:

• Pile temperature should stay between 90–130°F for active decomposition
• Add dry browns (cardboard, dried leaves) if the pile feels too wet from Miami winter rains
• San Diego's dry winter means you may need to add water to outdoor piles; check moisture (squeeze test: should feel like a wrung-out sponge)

Indoor composting advantage in Zone 10: Because the Zone 10 garden demands compost every 6–8 weeks year-round, having a steady indoor compost source is more valuable here than in any other zone. An electric kitchen composter processes scraps in a controlled environment regardless of outdoor weather, with no pile management required. The output integrates into soil quickly in Zone 10's warm-even-in-winter soil biology, making the cycle from kitchen scrap to garden amendment faster and more reliable than in colder climates.

For context on how the fall planting sets up this winter harvest, see our Zone 10 fall planting guide. For the summer strategy that bookends this peak season, see our Zone 10 summer planting guide.

Frequently Asked Questions

Is Zone 10 really frost-free in winter? Not entirely. Most Zone 10 locations go 3–5 years between frost events, but they do occur. Miami has experienced damaging frosts in January 2010, January 1977, and December 1989. Coachella Valley gets frost more regularly — January overnight lows of 28–32°F occur in some winters. San Diego coastal areas rarely freeze but inland valleys like El Cajon and Ramona can see frost December through February. The practical rule: expect frost-free winters but keep row cover on hand and monitor extended forecasts in January. Most Zone 10 crops are frost-tolerant; tender crops (tomatoes, peppers, eggplant) are the priority for frost protection.

Why are my January carrots so much sweeter than the ones I grew in spring? This is a well-documented phenomenon in root vegetable physiology. Carrots convert starches to sugars as a cold-hardening response — the cooler the soil temperature, the more sugar accumulates in the root. Zone 10 January carrots are growing in 55–62°F soil (compared to 75–80°F spring soil in the same climate) and experiencing nighttime air temperatures that further accelerate this conversion. It is the same reason parsnips are harvested after frost in northern climates. The same effect applies to beets, turnips, and even kale — all are genuinely sweeter in Zone 10 winter than in spring or fall [University of Florida IFAS Extension, 2024].

When should I harvest broccoli in Zone 10 winter? Harvest broccoli when the central head is 4–8 inches across and all the individual florets are tight, green, and closed. The most common mistake is waiting too long — if any of the tiny florets begin to open and show yellow flower petals, flavor declines immediately and the head is past peak. In Zone 10, harvest in the morning before daytime warming. After cutting the central head, leave the plant in the ground; side shoots will produce harvestable secondary heads for 4–6 additional weeks in broccoli varieties like Belstar and Calabrese.

How do I keep lettuce productive all winter in Zone 10? Zone 10 winter is the ideal lettuce season — no bolt pressure, mild temperatures, and abundant sunlight. The key to continuous production is cut-and-come-again harvesting: cut outer leaves to 2 inches above the stem rather than pulling whole plants. Succession sow every 3 weeks from October through February to stagger maturity. For heading types (Buttercrunch, Little Gem), harvest entire heads at 4–6 inches in diameter and immediately replant the space. Apply 1 inch of compost topdress after each harvest cycle to replenish nutrients and maintain the vigorous growth Zone 10's mild winter enables.

Can I grow broccoli and tomatoes in the same Zone 10 winter bed? Yes — this is one of Zone 10's unique advantages. A raised bed can simultaneously host October-transplanted tomatoes (24–36 inches tall, at the north end of the bed to minimize shade) and brassicas or greens at the south end. Because the cool season and warm season are no longer strictly separated — tomatoes and broccoli both thrive in Zone 10 winter's 72–80°F days and 60–68°F nights — intercropping them is both practical and productive. Use the space between tomato plants for fast cool-season crops (radishes, arugula, Asian greens) that complete their cycle before the tomato canopy expands too far.

References

1. University of Florida IFAS Extension. (2024). Vegetable Gardening in Florida. https://edis.ifas.ufl.edu/publication/VH021

2. University of Florida IFAS Extension. (2024). Short-Day Onion Production in Florida. https://edis.ifas.ufl.edu/publication/HS36

3. UC Cooperative Extension San Diego. (2022). Vegetable Planting Guide for San Diego County. https://ucanr.edu/sites/sdmg/

4. University of Arizona Cooperative Extension. (2023). Fall and Winter Vegetable Gardening in the Low Desert. https://extension.arizona.edu/fall-winter-vegetable-gardening

5. USDA Agricultural Research Service. (2023). USDA Plant Hardiness Zone Map. https://planthardiness.ars.usda.gov/

6. University of Florida IFAS. (2023). Soil Management for Florida Vegetable Gardens. https://edis.ifas.ufl.edu/publication/SS316