Brussels sprouts are the slowest brassica and the fussiest about heat — in Zone 11 they are a cool-season-only crop that rewards patience with sprouts along a tall, sturdy stem. This guide answers "when to plant brussels sprouts zone 11" directly: when to sow, how to start it, what soil and spacing it needs, how to water and feed it, which neighbours help, which pests to watch, and when to harvest. Zone 11 is frost-free, with average winter lows of 40 to 50°F, so there is no last or first frost date to plan around — here you plant by heat and by the wet and dry seasons, not by frost. See the full planting calendar for the whole year, and check your local extension service for advice specific to your area.
Brussels Sprouts at a glance in Zone 11
All figures below are broad published ranges from standard horticultural references, not exact figures for any variety or garden — they vary by variety, climate and soil. Use them to compare crops and to plan, not as promises.
| Detail | Brussels Sprouts |
|---|---|
| Days to germinate | 7–14 |
| Days to maturity | 80–100 |
| Spacing (inches) | 18–24 |
| Soil pH | 6.0–7.0 |
| Sun | full sun |
| Sowing method | both |
| Cold tolerance | frost-tolerant |
| Water needs | moderate |
When to plant brussels sprouts in Zone 11
Start brussels sprouts at the very beginning of the cool season, since the published maturity range is 80–100 days and the plants must finish while the weather is still cool. In Zone 11, sprouts sown late never form tight buttons — heat makes them loose, bitter and open. Sow or start seed in late autumn so plants are well grown before the warm season returns. Because the zone is frost-free, with winter lows of 40 to 50°F, there is no frost date to count back from — work from the cool season instead, and check your local extension service for the best sowing window in your area. Be honest: brussels sprouts are one of the hardest brassicas in the tropics, and a poor year is normal. Our November in Zone 11 guide shows what else to sow and harvest that month in Zone 11.
Starting brussels sprouts
Start seed indoors or sow directly, since both methods work and the published germination range is 7–14 days. Starting indoors gives you control over the timing, which matters with such a long season — sow in trays, transplant when seedlings have four or five true leaves, and harden them off first. Space plants as shown in the table below; brussels sprouts grow tall and need room for air to move between them. Firm the soil well around each plant — loose plants rock in the wind and produce poor sprouts. Use the seed-starting calculator to time your sowing so plants finish in the cool season.
Soil, spacing and sun
Brussels sprouts want firm, fertile, well-drained soil with a soil pH of 6.0–7.0. Dig in compost before planting, but do not overfeed with nitrogen, which grows loose, leafy sprouts instead of tight buttons. The soil should be firmed, not fluffy — tread the ground around each plant after transplanting. Mulch to keep roots cool and moist, and stake tall plants in windy sites so they do not lean. In the wet season, drainage matters: waterlogged roots invite clubroot, the worst disease of brassicas. Rotate brassicas to fresh ground each year.
Watering and feeding
Brussels sprouts need moderate, steady water from transplanting to harvest. Dry spells make sprouts small and bitter, while waterlogging invites disease, so water deeply at the base and mulch to even out moisture. Water in the morning so leaves dry before night in humid air. Feed lightly halfway through growth with compost tea, but skip heavy nitrogen feeds. As sprouts begin to form, remove the yellowing lower leaves so air moves around the stem and light reaches the buttons — this also makes picking easier.
Companion planting
Good companions for brussels sprouts are marigolds, basil, onions and lettuce. Onions help deter cabbage pests, marigolds at the bed edge discourage soil pests, and lettuce can be grown between young plants as a catch crop. Basil attracts beneficial insects. Avoid planting brussels sprouts next to other brassicas such as cabbage, broccoli or kale, since they share pests and diseases, and never follow one brassica with another in the same bed — rotate to beans or a root crop to break the pest cycle. For a cooler-climate comparison, see how the same crop is timed in Zone 9.
Pests and problems
Watch for cabbage worms, aphids, flea beetles and slugs. Cabbage worms — the green caterpillars of the white butterfly — are the main enemy: check the undersides of leaves weekly and pick them off, or cover the bed with fine insect mesh from transplanting. Aphids cluster in the growing tip and can be washed off with water. Flea beetles riddle young leaves with holes; mesh and moist soil keep them down. Slugs chew young plants at night in humid weather. Remove yellowing leaves promptly so pests have fewer places to hide.
Harvest and storage
Pick sprouts from the bottom of the stem upwards, starting when the lowest buttons are firm and about an inch across, usually within the published maturity range of 80–100 days from sowing. Twist or cut each sprout off cleanly and keep picking upwards as the upper buttons size up. When the top of the plant is reached, cut off the growing tip — this pushes the plant's energy into the remaining sprouts. Do not wait for all the sprouts to be ready at once; they mature over weeks. Fresh sprouts keep for a week or two in the fridge, and they taste best after a cool night. If you are planning the rest of the bed, our guide to Collard Greens in Zone 11 covers another crop from the same Zone 11 season.
Frequently asked questions
When should I plant brussels sprouts in Zone 11?
At the start of the cool season, so the 80–100 day crop finishes while it is still cool. Late sowings give loose, bitter sprouts or none at all.
Why are my sprouts loose and open?
Heat, or too much nitrogen. Grow them in the coolest months, feed lightly, firm the soil around plants, and pick from the bottom up as buttons tighten.
Do brussels sprouts need frost to taste good?
Frost sweetens them in cold climates, but Zone 11 is frost-free, with winter lows of 40 to 50°F. Here, cool nights are the closest you get — harvest after a cool spell for the best flavour.
How do I stop cabbage worms on brussels sprouts?
Cover the bed with fine insect mesh from transplanting, and check leaves weekly for green caterpillars. Pick them off by hand — mesh is the most reliable defence in a humid garden.