Bok choy is one of the best leafy vegetables for a tropical garden: it grows fast, it copes with warmth better than most brassicas, and it is ready in just 45–60 days. In Zone 12 it is a genuine cool-season success, as long as you sow it in the mildest months and give it shade and steady water. This guide tells you exactly how to grow it: when to sow, how to start seed, what soil and spacing bok choy needs, how to water it, which neighbours help, which pests to watch, and when to harvest. Zone 12 is frost-free, with average winter lows of 50 to 60°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.
Bok Choy at a glance in Zone 12
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 | Bok Choy |
|---|---|
| Days to germinate | 7–10 |
| Days to maturity | 45–60 |
| Spacing (inches) | 8–12 |
| Soil pH | 6.0–7.5 |
| Sun | part shade |
| Sowing method | both |
| Cold tolerance | hardy |
| Water needs | moderate |
When to plant bok choy in Zone 12
Sow bok choy in the coolest months — roughly January in most Zone 12 areas — for the mildest growing weather. The published maturity range is 45–60 days, so it fits the cool season well, and you can sow small batches every few weeks for a continuous supply. Bok choy is more heat-tolerant than most brassicas, but hot weather still makes it bolt, so the coolest months are the safest bet. Because the zone is frost-free, with winter lows of 50 to 60°F, there is no frost date to count from — sow by temperature and by the wet and dry seasons, and check your local extension service for advice specific to your area. Our January in Zone 12 guide shows what else to sow that month.
Starting bok choy
Start bok choy indoors or sow directly: germination takes 7–10 days and seedlings are quick and vigorous. Sow in individual pots or modules, or direct in the bed, and thin to the strongest plants. Space plants 8–12 inches apart — they grow into neat rosettes and need room for air to circulate. Transplant carefully and water in well, or sow direct and thin once seedlings are a few inches tall. The watering calculator helps you plan how much water a bed of leafy greens needs in the dry season. Bok choy is forgiving of a rough start, which makes it a good first brassica.
Soil, spacing and sun
Bok choy needs rich, well-drained soil with a soil pH of 6.0–7.5. Dig in plenty of well-rotted compost before planting, since bok choy is a hungry feeder for its size. Good drainage matters in tropical wet seasons, so a raised bed is the safest choice. Part shade suits bok choy in Zone 12 — it is one of the few vegetables that prefers some shade, and afternoon shade keeps the leaves tender and slows bolting in hot spells. Mulch thickly to hold moisture and keep the soil cool. Feed lightly through the season with compost or a balanced liquid feed.
Watering and feeding
Bok choy needs moderate, steady water. Keep the soil evenly moist from planting to harvest — dry spells make leaves tough, bitter and quick to bolt. Water at the base in the morning, and mulch thickly to slow evaporation in tropical sun. In the dry season, a deep soak every day or two may be needed, especially in pots. Avoid wetting the leaves late in the day, since damp foliage in humid air invites disease. Consistent moisture is the key to crisp, tender bok choy; a single dry spell can ruin a whole row.
Companion planting
Good companions for bok choy are marigolds, basil, onions and lettuce. Onions are useful neighbours that may help confuse cabbage pests. Lettuce can fill the gaps between young plants and shades the soil. Marigolds at the bed edges may help with soil pests. Avoid planting bok choy next to other brassicas in the same season, since they share pests, and do not follow any brassica with another brassica in the same bed — rotate to a different family next season. For another brassica from the same season, see our guide to Kohlrabi in Zone 12.
Pests and problems
Watch for cabbage worms, aphids, flea beetles and slugs. Cabbage worms are the main threat: the small white butterflies lay eggs on the leaves and the green caterpillars chew holes. Cover plants with fine insect mesh from planting, and check the undersides of leaves weekly, picking off caterpillars by hand. Aphids cluster on tender growth and can be washed off with water. Flea beetles pepper young leaves with small holes — mesh helps here too. Slugs hide in the damp shade at the base; check at night and remove them by hand.
Harvest and storage
Harvest bok choy when the heads are full and the leaves are crisp, usually within the published maturity range of 45–60 days from sowing. Cut the whole head at the base, or pick the outer leaves as needed for a longer harvest. For baby bok choy, harvest young at just a few inches tall — it is at its sweetest and most tender. Eat fresh the same day for the best flavour, or store in the fridge for a few days. Bok choy is excellent in stir-fries, soups and noodle dishes. In Zone 12, harvest promptly — hot weather turns it bitter and makes it bolt fast.
Frequently asked questions
Is bok choy good for Zone 12?
Yes — it is one of the best brassicas for Zone 12. It matures in just 45–60 days, prefers part shade, and copes with warmth better than most brassicas. Sow in the coolest months.
Does bok choy need full sun?
No — part shade suits it in Zone 12. It is one of the few vegetables that prefers some shade, and afternoon shade keeps the leaves tender and slows bolting.
Why did my bok choy bolt?
Heat is the usual cause. Bok choy bolts when temperatures climb, so sow in the coolest months, give it afternoon shade, and harvest as soon as heads are full.
How do I stop cabbage worms?
Cover plants with fine insect mesh from the day you plant them out, and check leaf undersides weekly for caterpillars. Mesh is far more reliable than spraying in a tropical garden.