Zone 13 is the hottest USDA zone and the only one that is frost-free year-round, with average winter lows above 60°F. There is no last spring frost and no first autumn frost to plan around, so in Zone 13 you plant by heat and by the wet and dry seasons, not by frost. The limits on what grows are heat, humidity, rain and pests rather than cold. All numbers below are published ranges, not promises for your garden: check your local extension service before you plant.
Collard greens are the toughest of the leafy brassicas and the most heat-tolerant of the cool-season greens, which makes them the best bet if you want greens in Zone 13. They are still a cool-season crop — heat makes them tough and bitter — but they hold up longer into warming weather than lettuce or spinach, and they produce for months if you pick the outer leaves and let the centre keep growing.
Zone 13 timing for collard greens
The table below is the whole plan in one place.
| Step | Zone 13 timing |
|---|---|
| Average winter low | Above 60°F |
| Last spring frost | None — frost-free year-round |
| First autumn frost | None — frost-free year-round |
| Best planting window | Coolest months only, roughly November to February |
| Start indoors | Optional head start indoors a few weeks before transplanting |
| Direct sow outdoors | Sow direct the coolest months, roughly November to February, or transplant seedlings |
| Days to germination | 7–10 days |
| Days to maturity | 60–80 days |
| Cold tolerance | frost-tolerant |
When to sow collard greens in Zone 13
Sow collard greens in the coolest months, roughly November to February, so plants establish while the weather is mild. They can be sown a little earlier than more delicate greens and will keep producing into the start of the warm season, but a midsummer sowing is a waste of seed. Succession-sow every three to four weeks through the cool season for a steady supply.
Starting collard greens: indoors or direct sowing
Collard greens can be started indoors or direct-sown. Starting indoors gives you sturdy transplants and a head start on the short cool season; direct sowing is simpler and works well if the soil is moist. Either way, thin or space plants to the spacing in the table — crowded collards stay small and attract pests.
Soil, spacing and sun
Collard Greens needs full sun. Space plants 12–18 inches apart — crowded plants compete for light, water and air, and disease spreads faster between touching leaves in humid tropical air. Collard greens want rich, moisture-holding soil with plenty of compost, and full sun in the cool season. They are hungry feeders, so dig compost in before planting and side-dress with more compost as they grow. A mulch keeps the soil cool and moist, which matters even in the cool season under a tropical sun. Use the plant spacing calculator to work out how many plants fit in your bed at that spacing.
Watering collard greens in Zone 13
Water needs are moderate, but collards wilt fast in a dry spell and the leaves turn tough if watering is uneven. Water deeply at the base, mulch thickly, and water in the morning. Consistent moisture is the difference between tender leaves and leathery ones. Use the watering calculator to work out how much water your bed needs.
Companion plants
Good companions for collard greens include marigolds, basil, onions, lettuce. These are the companions listed for this crop in standard horticultural references: they share similar needs, and some, like marigolds, are traditionally planted to help confuse or deter pests. Plant companions in the same bed or nearby, not in a separate corner of the garden, so they actually share the space. Avoid planting heavy feeders that will compete for the same nutrients in the same spot.
Common pests and problems
The pests to watch for are cabbage worms, aphids, flea beetles and slugs. Cabbage worms are the main enemy: check leaf undersides weekly for tiny green caterpillars and eggs, and hand-pick them before they skeletonise leaves. A light row cover over young plants keeps cabbage white butterflies from laying eggs in the first place.
Harvest and storage
Start harvesting outer leaves once plants are well established, about two to two and a half months after sowing, and keep picking from the outside while the centre keeps growing. Pick in the morning when leaves are crisp, and use them the same day — collards are best fresh. A plant picked this way can produce for months in the cool season.
Succession and rotation in Zone 13
Succession sowing works in Zone 13, but only inside the cool season: sow a small batch every two to three weeks while the weather stays mild, so the harvest stretches out instead of arriving all at once. Once heat builds, stop sowing — a late batch will bolt before it is worth picking. Rotate crops so collard greens does not follow another Brassicaceae family crop in the same bed next season. Keep notes on what you sowed and when: in a climate with no frost dates, your own records are the most useful planting guide you will have for the next cool season.
Related Zone 13 guides
More Zone 13 guides: Mustard Greens in Zone 13 and the same crop in a cooler zone, Collard Greens in Zone 11. The December in Zone 13 guide shows what else to plant in that month, and the planting calendar hub brings all the Zone 13 guides together.
Frequently asked questions
When should I plant collard greens in Zone 13?
Sow collard greens in the coolest months, roughly November to February. Zone 13 is frost-free with winter lows above 60°F, so there is no last or first frost date to work from — plant by the cool season, not by frost. Check your local extension service for the best sowing weeks in your area.
Are collards really the best green for Zone 13?
Among the leafy brassicas, yes: they tolerate heat better than kale, lettuce or spinach and keep producing longer. They are still a cool-season crop, so do not expect midsummer harvests — but for the coolest months they are the most reliable green you can grow.
How do I stop cabbage worms eating my collards?
Cover young plants with fine insect netting or row cover before butterflies find them, and check leaf undersides weekly for eggs and caterpillars. Hand-picking works well on a small bed, and healthy, well-watered plants recover from light damage faster than stressed ones.
What soil and spacing do collard greens need?
It needs full sun, soil pH 6.0–7.5, and spacing of 12–18 inches between plants. Work compost into the bed before planting and test the soil rather than guessing the pH.