Turnips are a hardy cool-season root for Zone 12, and they give two harvests from one sowing: the roots and the greens, both edible. With winter lows of 50 to 60°F, turnips grow best in the coolest months, roughly December through February, maturing in 40–60 days, and they are one of the easiest roots to grow in the tropics — provided you sow them in the cool window and harvest them young.
The Zone 12 challenge is heat. These are cool-season crops, and in a frost-free tropical zone the coolest months are short — plant by the coolest part of the year, give afternoon shade, and accept that the season is brief and the harvest smaller than in a cool climate.
Zone 12 at a glance
USDA Zone 12 covers the warmest lowland parts of Hawaii and Puerto Rico. Winters are very mild, with average winter lows of 50 to 60°F, frost is unknown, and the growing season runs all year. Zone 12 has no average last spring frost and no average first autumn frost — it is frost-free year-round — so planting dates here are averages and guidance, not exact dates for any one garden; check your local extension service before planting.
| Detail | Zone 12 guidance |
|---|---|
| Average winter low | 50 to 60°F |
| Average last spring frost | frost-free (no frost dates) |
| Average first autumn frost | frost-free (no frost dates) |
| Days to germination | 7–10 days |
| Days to maturity | 40–60 days |
| Sowing | direct sow |
| Sun | full sun |
| Soil pH | 6.0–7.0 |
| Spacing | 4–6 inches |
| Water needs | moderate |
| Cold tolerance | hardy |
When to plant turnips in Zone 12
Plant turnips in Zone 12 in the coolest months only, roughly December through February. Seeds germinate in 7–10 days and the crop matures in 40–60 days, so a sowing made in December is ready around January to February. Zone 12 is frost-free, so there are no last or first frost dates — check your local extension service for advice on your own microclimate. Sown outside the cool window, this crop bolts, turns bitter or fails to size up in the heat, so treat the coolest months as the whole season and plan other crops for the hot months.
The planting calendar hub and the December in Zone 12 month guide show what else is happening at planting time.
Starting turnips in Zone 12
Sow turnips direct where they are to grow — they germinate in 7–10 days and dislike transplanting. Sow in the coolest months, space seed 4–6 inches apart, and thin seedlings to one strong plant per station once they are big enough to handle.
See also when to plant turnips in Zone 11 for the same crop in a slightly cooler zone.
Soil, spacing, sun and water
Turnips need full sun and loose, well-drained soil with a pH of 6.0–7.0. Dig the bed over and work in well-rotted compost, space plants 4–6 inches apart, and keep the soil evenly moist — turnips that dry out turn woody and strong-flavoured. They need full sun and a soil pH of 6.0–7.0. Water needs are moderate: water deeply and regularly at the base, in the morning, so leaves dry before night. The germination time calculator can help you plan the bed before you plant.
Companion planting
Marigolds, basil, onions and lettuce are good companions for turnips. Onions and lettuce fill the bed without competing for root space, marigolds edge the bed, and radishes share the same cool-season window, so the two root crops can be sown side by side. The companion planting finder can suggest combinations for your whole bed, and our guide to when to plant radishes in Zone 12 shows another crop that shares the same planting windows.
Pests and problems
The common pests and problems to watch for with turnips are cabbage worms, aphids, flea beetles, slugs. Cabbage worms are green caterpillars that chew holes in leaves; check leaf undersides and hand-pick, or cover with fine mesh. Aphids cluster on soft new growth and leaf undersides; wash them off with a strong jet of water and encourage ladybirds. Flea beetles chew small holes in leaves, worst on young seedlings; fine mesh row cover and mulching help. Slugs feed at night, leaving ragged holes and slime trails; water in the morning and keep the bed clear of debris. Your local extension service can confirm an identification if the damage is severe.
Harvest and storage
Pull turnips when the roots are young and tender — in Zone 12, harvest them small rather than waiting for maximum size, because large roots turn woody fast in warm soil. Pick the greens as well: young turnip tops cook like other leafy greens. Fresh turnips keep for several weeks in the fridge in a bag, with the tops removed. Cooked turnips freeze well, and the greens can be blanched and frozen like spinach.
Frequently asked questions
When should I plant turnips in Zone 12?
Plant turnips in Zone 12 in the coolest months only, roughly December through February. Zone 12 is frost-free year-round, so there are no last or first frost dates — plant by the heat and the wet and dry seasons, and check your local extension service for your own microclimate.
Why are my turnips woody?
Roots left in the ground too long, especially as the weather warms, turn woody and strong-flavoured — in Zone 12 this can happen within days. Harvest turnips young, sow only in the coolest months, and keep the soil moist.
Can I grow turnips in Zone 12 year-round?
No — not well. This is a cool-season crop, and outside the coolest months, roughly December through February, it bolts, turns bitter or fails to size up in tropical heat. Grow it in the cool window, and plant heat-loving crops in the hot months instead.
Do turnips need thinning?
Yes — turnip seedlings that are never thinned compete with each other and never swell. Thin to 4–6 inches apart once seedlings are big enough to handle, and use the thinnings as cooking greens.