Can You Plant Carrots in September? Yes in Zone 7 and Warmer (Here Is the Cutoff by Zone)

Yes, if your average first frost is November 1 or later. That is zone 7b and warmer, and it is a real window rather than a technicality: zone 7b has until about September 6, zone 8a until September 13, zone 8b until September 20, and zone 9a does not close until October 5. In zone 7a the sow-by date is August 30, so the first few days of September overshoot it by less than a week, which a row cover at the other end of the season covers comfortably.

If you are in zone 6 or colder, the answer is no for a full-size crop. Zone 6a closed on August 18 and zone 5a on August 8. You can still sow and cut baby carrots, and you can sow into a cold frame, but a September sowing in zone 5 will not make dinner-plate carrots before the ground freezes.

Find your own frost date

The zone averages below are representative. The date that actually decides this is the one for your ZIP.

Carrot sow-by dates for every zone

The per-zone detail, including spring dates and succession sowings, is on the carrots crop page, and the two zones this question comes up in most have their own pages: carrots in zone 7a and carrots in zone 9a.

Where 56 days comes from

Every fall date on this site is the same subtraction, and carrots are the clearest example of why it is not just days to maturity.

Start with 70 days to maturity, which is typical for a main-season carrot. Add 14 days, because seed packet numbers are measured in spring conditions with lengthening days and warming soil, and after the September equinox you get the opposite. Growth slows, and most extension services put the correction at about two weeks. That gives 84 days.

Then subtract 28 days, because a carrot does not stop at the first light frost. It keeps sizing up through several of them, and the root holds in the ground long after the tops are finished. That frost tolerance is real growing time you get back, and it is why carrots have a later deadline than a radish crop that matures in 28 days but is done the moment it is ready.

70 plus 14 minus 28 is 56. Count 56 days back from your first frost and you have your sow-by date.

Notice what this does to the harvest column in the table. A carrot sown on the sow-by date is ready roughly two weeks after your first frost, not before it. That is intentional. Pulling carrots after frost is the point.

What frost actually does to a carrot

A light frost, 29 to 32 degrees, does nothing bad to carrots at all. The tops take it without damage and the roots keep growing in soil that is still well above freezing.

A hard freeze, 25 to 28 degrees, burns the tops back. The roots underneath are unaffected and stay perfectly usable. This is the stage where a lot of gardeners give up on a bed that is still full of food.

Below that, the thing that damages carrots is the root itself freezing and thawing repeatedly, which turns the texture to mush. Four to six inches of straw over the row prevents it by keeping the soil unfrozen, and that is how people in zones 5 and 6 dig carrots through December. Put the mulch on before the ground starts to freeze, and mark the row, because you will not find it under snow otherwise. First frost dates and frost protection covers what different covers buy you at each of those thresholds.

The reward for leaving them is flavour. Carrots respond to falling soil temperature by converting stored starch into sugars, which lowers the freezing point inside their cells. It is antifreeze, and it tastes like candy. A fall carrot and a summer carrot of the same variety are not the same vegetable.

Texas: September and October, and fall is the better season

Texas spans zone 6b in the far northern Panhandle to zone 9b in the Rio Grande Valley, so there is no single date, but for most of the state September is squarely in the window.

Dallas and most of North and Central Texas sit around zone 8a, where the sow-by date is September 13. The Austin and Houston band runs zone 8b, which gives you until about September 20. The coastal strip and the lower valley are zone 9a and 9b, where the date is October 5 or later. The Panhandle around Amarillo is zone 6b to 7a, and there the deadline was late August.

The more useful point for Texas gardeners is that fall is the better carrot season, full stop. A spring sowing germinates in cool soil and then matures into June heat, which produces carrots that are woody and often bitter. A fall sowing does the reverse: it germinates in heat, which is the hard part, and then sizes up through cooling weather into the sweetening range. Get the September planting in and you harvest into December in most of the state.

Utah: September is late almost everywhere

Utah runs from zone 4 in the high mountain valleys to zone 8b in the far southwest, and most of the population lives in between.

The Wasatch Front, from Ogden through Salt Lake City to Provo, sits around zone 6b to 7a. The sow-by dates there are August 23 and August 30, so a September carrot sowing is already past the line. It is not automatically hopeless: sowing in the first few days of September and covering the bed with a low tunnel in late October buys back roughly the two weeks you are short. Expect smaller carrots and treat them as a bonus.

St. George and the southwest corner are the real exception. At zone 8b the window runs to about September 20, which makes it the one part of Utah where September carrot planting is normal rather than a gamble.

The mountain valleys, zones 4 and 5, closed in early August. Sow thickly for baby carrots or wait for spring.

Georgia: the main fall carrot month

Georgia is mostly zone 8a and 8b, with zone 7a and 7b in the north Georgia mountains and zone 9a on the coast near the Florida line.

That puts the sow-by date at September 13 for the Atlanta band and much of the Piedmont, September 20 across south and central Georgia, and October 5 on the coast. In the mountains around Blue Ridge the deadline is September 6 or a few days earlier.

Georgia has the same argument as Texas in favour of a fall crop, with the added benefit that fall rainfall usually does the germination watering for you. The risk is the opposite: a wet September can crust a seedbed and drown shallow-sown carrot seed.

California: September is early, not late

California is the state where the frost arithmetic matters least and the heat arithmetic matters most.

The Central Valley runs zone 9a to 9b, where the sow-by dates are October 5 and October 15. The Bay Area and the Southern California coast run zone 9b to 10b, which pushes the date to late October or into November. In those places September is not the end of the window, it is the beginning of one, and the real question is whether your soil is cool enough for carrot seed to germinate rather than whether frost will catch the crop.

The Sierra foothills and mountains are a different state as far as planting goes. Zone 6 and 7 there have August sow-by dates, the same as the rest of the country at those zones.

On the mild coast, where frost is effectively absent, carrots can be sown across most of the year and the practical limits are summer heat at one end and short winter days at the other.

Florida: October through February

Florida is the clearest case of a state where the calendar advice from further north is simply wrong. Zone 9a in the panhandle and north Florida has an October 5 sow-by date, central Florida at 9b and 10a runs to mid or late October, and south Florida has no frost date to count back from at all.

In practice the Florida carrot window is October through February. September is not too late, it is too hot: carrot seed sits in soil in the 80s and 90s and either fails to germinate or produces a thin, uneven stand. Waiting for the heat to break gives you a far better crop, and successive sowings from October into February keep it coming.

If you are past your date

You have four options, in rough order of how well they work.

Sow anyway and harvest small. Carrots are edible at every size, and a thickly sown row cut as fingerlings in 45 to 50 days is a legitimate crop rather than a consolation prize.

Add a row cover or a low tunnel. Fabric on hoops buys roughly two weeks of effective season, which moves a zone 6b deadline from August 23 to early September and a zone 7a deadline into the second week.

Switch crops. Radishes need only 21 days before frost, and spinach sown now is not trying to mature at all, it is establishing to overwinter. Both are still open in zones where carrots are not.

Or plan for next year and put the date in your calendar in July, which is when the decision actually gets made in zones 3 through 6. Check the averages against your own location on the frost dates page before you do.

Getting carrot seed up in warm soil

This is the part that decides a fall carrot crop, not the sowing date.

Carrot seed is small, slow and shallow. It germinates in roughly 14 to 21 days, wants no more than a quarter inch of soil over it, and dies if that quarter inch dries out once. In September, in the zones where September sowing works, that surface dries out in an afternoon.

Sow into a furrow you have already watered, so the seed lands on damp soil rather than dry. Cover lightly, and cover the row itself with a board, a strip of burlap or a length of shade cloth. Check every day and pull it off the moment you see green, because carrot seedlings stretch fast in the dark. Water with a fine rose twice a day rather than once deeply, since the goal is a surface that never dries rather than a wet bed.

A light scatter of radish seed along the row marks it, breaks any crust, and gets pulled before the carrots need the space. It is an old trick and it still works.