When to Plant Carrots (Spring and Fall Timing by Zone)

Carrots grow underground for two to three months before you ever see the payoff, so getting the start right matters more than with a fast crop. Sow too early into cold, wet dirt and the seed just rots. Sow too late and the roots stay stubby before the ground freezes. The fix isn't a date on a seed packet. It's your soil thermometer and your frost dates.

This guide walks spring timing by zone, the soil-temperature numbers extension offices actually use, how carrot varieties differ in days to maturity, and why a fall sowing often beats a spring one on flavor.

Spring sowing by zone

The rule holds everywhere: sow once the soil can be worked and has cleared 40 to 45 F, roughly 2 to 4 weeks before your last frost. Washington State University Extension times it to 2 to 4 weeks before the last spring frost. University of Illinois Extension states it more loosely: sow as soon as the soil can be worked in spring.

Cold ground thaws late, so cold zones sow late. Use the table as a starting point, then check your own thermometer and frost date, since a warm spring or a cold snap can shift either window by weeks.

University of Maryland Extension lists a spring window running roughly mid-April through May for its zone-7 area, with a second window for fall. Shift earlier heading south, later heading north.

Soil temperature: the number that actually decides it

Air temperature is a rough guide. Soil temperature is the real gate. A $10 soil thermometer pushed 2 inches down, read in the morning before the sun warms the surface, tells you more than any calendar.

University of Minnesota Extension notes that carrot seed germinates slowly in cold soil, and that below about 40 F you get patchy, delayed sprouting. Even in good conditions the seed takes 7 to 21 days to break the surface, so a slow-looking row is not automatically a failed one.

Carrots are almost always direct seeded where they'll grow to full size. The taproot resents disturbance, and transplanting usually leaves you with forked, stunted roots. Sow shallow, 1/4 to 1/2 inch deep, and keep the top inch of soil damp until you see green.

Days to maturity by type

Not every carrot finishes on the same clock. A short, quick Nantes and a long storage Danvers need different sowing dates if you want both ready when you plan.

Exact days vary by cultivar and by how warm your soil runs, so treat these as planning ranges, not guarantees. Most gardeners land in the 50 to 80 day band overall, which is why carrots planted in early spring are usually ready well before summer's worst heat.

How to tell it's time to sow

You don't need a perfect date. Three checks tell you it's go time:

1. The soil can be worked, not frozen or squeezed into soggy mud.
2. A soil thermometer reads at least 40 F two inches down, ideally 55 to 75 F.
3. You're within 2 to 4 weeks of your average last spring frost.
4. The bed is loose and free of stones 8 to 10 inches down, so roots grow straight instead of forking.

If all four line up, sow. A light frost after the seedlings are up won't hurt them.

Fall planting, and why cold makes carrots sweeter

Spring is the default sowing for most gardeners, but a fall crop is often the better-tasting one. Cold triggers the plant to convert starches to sugar, and university extension sources including Penn State and University of Connecticut note that carrots, along with other root crops, sweeten noticeably after a frost. Oregon State University Extension confirms a light frost improves flavor rather than damaging the roots.

For a fall harvest, count back 10 to 12 weeks from your first fall frost and sow then, per University of Maryland Extension. In zone 7 and warmer, that often means sowing in mid to late summer for a fall and early-winter pull, since mature roots hold up through repeated light freezes.

How far can you push it? Growing carrots tolerate light frost down to around 28 to 32 F. Once roots are sized up, they handle far colder soil, into the high teens and low 20s F, as long as the ground itself hasn't frozen solid. University of Illinois Extension notes carrots can stay in place and be dug through fall and into winter under a thick layer of straw mulch, a row cover, or a low tunnel, as long as you can still get a fork into the ground. In colder zones where the soil locks up hard, pull the crop before that happens rather than betting on mulch alone.

To eat carrots over a long stretch instead of all at once, succession sow a short new row every 2 to 3 weeks through spring, pause through the hottest weeks of summer, then pick the fall window back up. The same staggered rhythm works for other quick cool-season crops like radishes.

Spacing before you sow

Getting the timing right gets seed in the ground. Getting the spacing right is what turns that seed into full-size roots instead of a tangle of skinny pencils.

Sow seed thinly, then thin seedlings to 2 to 3 inches apart once they're a couple of inches tall. The how far apart to plant carrots guide covers in-row and between-row spacing in more depth, and the plant spacing calculator works out how many carrots fit your exact bed.

Your next step

Plant carrots in cool soil, 2 to 4 weeks before your last spring frost, once the ground has cleared 40 to 45 F. Sow a second round in mid to late summer, 10 to 12 weeks before your first fall frost, for a crop that finishes sweeter. Keep the seedbed damp until you see green, and thin to 2 to 3 inches once the tops are up.

Related reading

• When to harvest carrots — the signs that say it's time to pull them
• When to plant garlic — the fall-sow, cold-sweetened pattern shows up here too
• Plant spacing calculator — work out seed counts for any bed size