Brussels sprouts are the long, slow brassica of the Zone 10 winter garden: plant them in autumn, tend them for months, and harvest sweet, firm sprouts from late winter into spring. They are the last brassica to mature and one of the most satisfying when the cool weather does its work.
Zone 10 at a glance
USDA Zone 10 covers the warmest parts of the United States, including southern Florida, the southern tip of Texas, coastal southern California and Hawaii. Winters are mild, with average winter lows of 30 to 40°F, and the growing season runs nearly all year — frost is rare rather than a regular event.
The average last spring frost in Zone 10 is Jan 15–30 (frost rare), and the average first autumn frost is Dec 15–31 (frost rare). These are zone averages drawn from NOAA frost records, not exact dates for any one garden — always check your local extension service and the forecast before planting tender crops outside. Frost dates vary by microclimate, elevation and year, so treat them as a guide, not a promise. Use our frost date calculator for your zone's averages.
When to plant brussels sprouts in Zone 10
Plant brussels sprouts from October to December in Zone 10, setting out transplants in autumn. They are frost-tolerant and need a long, cool season: sprouts mature 80–100 days after transplanting, and the flavour improves after cool nights, so late-winter and spring harvests are the sweetest. Plants set out too late, or in spring, rarely size up before heat arrives. Because Zone 10 has a long, nearly year-round growing season, the question is rarely whether brussels sprouts will grow, but whether you plant them in the right season — heat lovers go in after the last frost, cool-season crops go in for autumn and winter.
Brussels Sprouts planting at a glance
| Detail | Zone 10 guidance |
|---|---|
| Best planting window | October to December |
| Start indoors | Either — start indoors or sow directly |
| Days to germination | 7–14 |
| Days to maturity | 80–100 |
| Spacing | 18–24 in |
| Soil pH | 6.0–7.0 |
| Sun | full sun |
| Water needs | moderate |
| Cold tolerance | frost-tolerant |
All figures are broad published ranges from standard horticultural references, and they vary by variety, soil and weather. Check your local extension service for advice on your own garden.
Starting brussels sprouts
Start brussels sprouts indoors and transplant them out for the most reliable results, though direct sowing works in autumn. Sow seed 4–6 weeks before transplanting; seed germinates in 7–14 days. Harden seedlings off and set them out in autumn, firming the soil well around the stem — loose plants rock in the wind and make loose sprouts. Cover young plants with insect netting to keep cabbage whites off them, and stake tall plants in windy spots.
Soil, spacing and sun
Brussels sprouts need full sun and firm, fertile, well-drained soil with a pH of 6.0–7.0. Unlike most vegetables, they prefer soil that is firm rather than fluffy, so tread the planting holes in well after transplanting. Work in compost before planting, but avoid over-feeding with nitrogen, which makes leafy plants with few sprouts. Space plants 18–24 inches apart — they grow tall and need room. Mulch to keep the soil cool and damp.
Watering and feeding
Brussels sprouts have moderate water needs and grow best with steady moisture: dry plants make small, loose sprouts that open early. Water deeply and regularly, and mulch to hold moisture through Zone 10's dry winter spells. A dry spell followed by heavy watering can split sprouts, so aim for even dampness. Water at the base to keep leaves dry, and reduce watering slightly once sprouts are sizing up.
Companion planting
Good companions for brussels sprouts are marigolds, basil, onions and lettuce. Marigolds at the bed edge are said to confuse cabbage pests, and onions may help mask the brassica scent. Lettuce fits between young plants and is harvested before the sprouts need the space. Avoid planting brussels sprouts near tomatoes and strawberries, and rotate brassicas to a fresh bed each year rather than following cabbage, broccoli or kale.
Pests and problems
The pests to watch for are cabbage worms, aphids, flea beetles and slugs. Cabbage white caterpillars are the main threat: check plants weekly and pick caterpillars off, or keep the bed under insect netting. Aphids cluster on the growing point and inside sprouts; a jet of water clears most. Flea beetles attack young leaves, and slugs hide under mulch. Tall, well-fed plants with good air flow resist pests better than crowded, stressed ones.
Harvesting and storing brussels sprouts
Harvest brussels sprouts from the bottom of the stem upwards, 80–100 days after transplanting, picking sprouts when they are firm, tight and about an inch across. Twist or cut each sprout off, removing the yellowing leaf below it as you go. Picking from the bottom encourages the upper sprouts to size up. In Zone 10's long cool season, a plant can be picked over many weeks. Top the plant — pinch out the growing tip — a few weeks before you want the last sprouts, to push energy into sizing them up. Fresh sprouts keep for a week or two in the fridge.
Frequently asked questions
When do I plant brussels sprouts in Zone 10?
From October to December, as transplants. They need a long cool season — check your local extension service for the best dates in your area.
Why are my sprouts loose and open?
Usually heat, drought or loose planting. Firm the soil well at planting, keep plants watered, and grow them in the cool season.
Should I top my brussels sprout plants?
Yes, a few weeks before the end of the season. Pinching out the growing tip pushes energy into the sprouts and helps them size up evenly.
How long do brussels sprouts take to grow in Zone 10?
Seed germinates in 7–14 days and sprouts mature in 80–100 days from transplanting.
For the full year, browse the planting calendar hub. Nearby: october in Zone 10, Brussels Sprouts in Zone 9 and Broccoli in Zone 10. Use the seed-starting calculator and the harvest date calculator to plan your own dates.