In north Florida, sow warm-season cover crops after the last spring freeze window (February 16 to March 7) and cool-season ones ahead of the first fall freeze window (November 26 to December 13). Those dates come from Jacksonville and describe north Florida only. Central and south Florida are effectively frost-free, so the calendar flips: winter is the main season and summer is the hard one.
The short answer for Florida
Plant warm-season cover crops in north Florida once the spring freeze window has passed, and plant cool-season ones in fall before the freeze window opens. In the rest of the state, build the calendar around summer heat instead of frost, and put your main planting in the cooler months.
The dates deserve a precise reading. They come from NOAA’s 1991-2020 Climate Normals for the Jacksonville airport station, and they mark the band where the probability of a 32°F freeze runs between 30 and 70 percent. They are probabilities, not a guarantee. Inside February 16 to March 7, a late freeze is still a real possibility. Inside November 26 to December 13, the first one may or may not have arrived yet. The airport is also an inland site, and three of the thirty falls in the record saw no freeze at all. A date that missed three years in thirty is a good guide, not a rule.
What the window means for sowing
For frost-tender summer cover crops, the safe habit is to wait until the later end of the spring window and let the soil warm before seeding. A seedling that has just emerged is the most exposed stage of the plant’s life. For winter cover crops, the goal is the opposite: get seed in the ground and germinated well ahead of the fall window, so the plants are established when cold arrives. Both ends of the calendar are set by that one band.
The coldest month adds context. The mean daily minimum in Jacksonville’s coldest month is 42.9°F. That is a cool night, not a killing one. Cool-season cover crops can keep growing through a north Florida winter, so winter survival is rarely the question. Timing and heat are.
Which species fit each slot is a separate question, covered in The Best Cover Crops for Florida. For the bigger picture of why cover crops earn their place in a Florida garden at all, start with Cover Crops for Florida Gardens.
What will not work here
Applying the Jacksonville window to Orlando or Miami will not work. It is the most common mistake in Florida planting advice, because most calendars online are written for the northern tier of the country and quietly assume a frost-bounded year. Central and south Florida do not have that boundary. Waiting for a “last frost” there means waiting for something that, in most years, never shows up, and the planting that gets skipped is the winter one, which is the best season you have.
Planting too early in north Florida fails in a different way. Sowing a frost-tender summer cover crop in late January or early February, because a warm week made it feel like spring, puts seedlings into a window where a 32°F freeze is still on the table. One cold night can erase the stand and the seed cost with it. The spring band runs to March 7 for a reason.
Summer is the other season that defeats a lot of gardeners. Cool-season cover crops sown into Florida’s summer heat have little chance. They are built for the cool half of the year, and in this climate they stall, thin out or never germinate evenly. If a bed sits empty from late spring through early fall, a heat-loving cover crop is the realistic choice, and the cool-season mixes should wait until the weather turns.
Humidity is the quiet problem. Warm, wet, humid weather keeps foliage damp for long stretches, and a dense, tightly seeded stand holds that moisture against the plants. Seeding rates that look reasonable on a package designed for drier regions can leave you with a matted, soggy canopy. Give summer stands room for air to move, and expect a heavy rain to flatten a thin-stemmed crop.
Hand-watering weekly, the habit that works in many places, also fails here if the summer is the dry stretch. Between afternoon storms, sandy ground can dry quickly, and then a downpour follows. A cover crop that needs regular irrigation to establish is a poor match for a calendar that swings that hard. Choose species that tolerate both, and sow ahead of the rainy stretch rather than depending on a hose.
What changes across Florida
Florida is not one garden. The USDA Plant Hardiness Zone Map (2023 edition, built on 1991-2020 normals) places the state across zones 8b to 11b. That system rests on one variable only, the average annual extreme minimum temperature, so it says how cold the worst night usually gets and nothing about summer heat or rainfall. A range of 8b to 11b means there is no single answer for the state. The calendar above is anchored to Jacksonville, and the other parts of Florida differ.
| Part of the state | Freeze pattern | How the calendar runs |
|---|---|---|
| North Florida (Jacksonville is the reference) | Freeze window Feb 16 to Mar 7 in spring and Nov 26 to Dec 13 in fall, with some years freeze-free | Two seasons bounded by frost: a warm season between the windows and a cool season after the fall one |
| Central and south Florida | Effectively frost-free | Inverted: the main season runs through winter, and summer is the hard part |
A reader in the northern counties, especially inland or away from the coast, should treat the Jacksonville dates as a starting point and lean toward the later end of the spring window. Cold air pools in low, open ground and settles in inland pockets, so these areas can feel the freeze band more sharply than a coastal lot. In the central and southern parts of the state, drop the frost dates entirely and plan around the heat and the rainy season.
Which zone you are in is something to read off the USDA map itself, not to guess from a neighbor or a nursery tag. Look up your location on the current USDA Plant Hardiness Zone Map and use it to see how far your garden sits from the Jacksonville reference.
Where to check this for your own county
A county recommendation beats a state one, and this page is the state one. Florida stretches a long way, and the spread between its northern and southern ends is wider than in many multi-state regions. Local agents know which cover crops were trialed in your county’s soils, what the local rainy season does to them and when growers there actually plant.
The place to start is UF/IFAS Extension, the University of Florida’s extension service, which has a county office across the state. Two items are worth looking for on your county’s page or by calling the office:
- The local planting calendar, ideally one that states dates for your county rather than a statewide range.
- The cover crop varieties trialed in your county, with notes on how they handled local heat, humidity and soil.
If the county office has no cover crop calendar of its own, ask which vegetable or field-crop planting dates it publishes. Cover crop timing usually follows those, since the cover crop fills the gaps between cash crops. Extension agents are used to questions like this, and a short phone call can save a failed planting.
Bring your own details when you ask. The nearest town, the type of soil in the bed and whether the bed floods in heavy rain will all change the answer.
Checking this against your own garden
No date on this page outranks what your own garden shows you. Three observations will tell you more than a calendar can.
Soil warmth, by feel. Push your hand a few inches into the bed in the morning. If the soil still feels cool and damp, warm-season seed will sit and may rot. If it feels comfortably warm, germination will be quick. A bed that warms earlier than a neighbor’s usually has more sun, drains faster or sits against a wall that holds heat.
The first flush of male flowers. Squash and cucumber vines, and oak catkins in the yard, bloom in step with the season. When the first male flowers open in your garden, spring warmth has arrived locally. If yours open ahead of the neighborhood, you have a warm microclimate. If they lag, you probably have shade or cold air settling at your site.
The first true leaves. The first pair of leaves on a seedling are seed leaves. The true leaves come next and look different. Sow a small test patch ahead of the main planting and note how long the true leaves take to appear. Slow, pale growth means the timing is off for your spot. Quick, even growth means you picked the right week.
Write the dates down each year. After two or three seasons, your notes will be a better calendar than anything printed for a whole state.
Some gardeners also time this by the Moon: when to plant cover crops by the moon, as almanac tradition rather than fact.
Common questions
Can I use Jacksonville’s frost dates if I garden in Orlando or Miami?
No. The dates describe north Florida. Central and south Florida are effectively frost-free, so the planting calendar inverts there, with winter as the main season and summer as the hard one.
What do the frost dates on this page actually measure?
They are NOAA 1991-2020 probabilities of a 32°F freeze, taken as a 30 to 70 percent band for the Jacksonville airport station. They are not guaranteed dates.
Do cool-season cover crops die in a Florida winter?
Rarely in the north. The mean daily minimum of the coldest month at the Jacksonville reference is 42.9°F, which is cool but mild. A hard freeze can still happen, so sow early enough for plants to establish before the November 26 to December 13 window.
Is the spring window a safe date to sow?
It is a probability band, not a clearance. Three of the thirty falls in the record had no freeze at all, and a late freeze inside the window is still possible, so wait for the later end if the seedlings are frost-tender.