On the shortest day of every year, I like to bundle up and head out to the garden with a spading fork. At the carrot bed, I pull back the fabric row cover and fork up a bunch of sweet, tender roots from the chill soil. Take my word for it: Winter carrots taste better than carrots grown in spring or summer.
Growing carrots for your winter table doesn’t require expensive equipment or much gardening experience. With a little advance planning, you too can eat fresh, homegrown carrots every December — and beyond. Here’s how to get started.
Countdown to Winter Carrots
To find the planting date for a winter crop of carrots, you’ll have to count backward from the first frost date in your area. (Plants don’t germinate or grow well in cold, low-light conditions, so your carrots will have to do most of their growing before frigid temperatures set in.) Check the seed packet for the days to maturity, and then count backward from the first frost date in your area. For example, the average first frost date in my area is October 20, and heirloom ‘Danvers 126’ carrots need 75 days of growth before harvest. Counting back from October 20, I discover that I should plant this cultivar in my garden around the first of August. By comparison, small ‘Paris Market’ carrots take only 55 days to mature, so their planting date for a winter crop would fall nearer the end of August. Most carrots take 50 to 70 days to mature, so you can use that as a rule of thumb if you have seeds of unknown cultivars you’d like to grow.
At this point, readers who garden in places with long, hot summers are thinking “I can’t get carrots to germinate in August!” Actually, you can. The trick is to keep the seeds consistently moist for the first few days, by covering them with wet burlap or cardboard. I like to use fabric row cover because it keeps the soil surface moist while letting sunlight penetrate. Whatever material you choose, check on your seedbed a couple of times each day to make sure the cover is moist. Look for seedlings underneath the cover every day, too. As soon as you see a fine crop emerging, remove the cover; the seedlings need light as much as they need moisture once they’re aboveground. Thin the seedlings when they’re about 2 inches high. (See “Growing Great Carrots” below for more advice.)
Keep your late-summer carrots well-watered so they’ll thrive despite the heat. Mulch will help with moisture retention, and if you water late in the day, the moisture will soak into the soil rather than evaporate. I also like to suspend fabric row cover over the seedlings as a shade cloth, offering them some relief from the relentless sun while allowing air and rain to penetrate. Plus, tender seedlings are attractive to the rabbits and the huge grasshoppers that proliferate in my summer garden. Row cover is a great way to keep them away from the buffet.
If you’ve been a decent carrot steward, you’ll have a good-looking crop by the time of your first average frost date. But don’t harvest just yet! Cold temperatures will sweeten your carrots by converting their starches into sugar, so allow a few light frosts to affect your crop before you taste any roots.
Winter Vegetable Garden Protection
The next step is to protect your crop during winter, when severe freezes, snow, and ice threaten to destroy it. Cold frames and mini hoop tunnels are great ways to offer crop protection. Both are basically small greenhouses, and using them is the equivalent of moving your garden one growing zone south. A cold frame is an open-bottomed box (often wood) supporting a transparent glass or plastic top that admits sunlight. I keep a loose cold frame to deploy around the garden as needed, but my favorite protection for winter carrots is a mini hoop tunnel, which is easy to assemble and inexpensive.
To make a mini hoop tunnel over my carrots, I push the ends of flexible 1⁄2 -inch PVC pipes into the ground on either side of the bed so they form arches to support a cover. I space my “hoops” about 3 feet apart along the length of the bed. Local hardware stores often stock precut 5-foot lengths of PVC; just be sure to buy flexible PVC, not rigid. For a 3-foot-wide garden bed, a 5-foot length of PVC creates just enough height to keep the cover from touching the carrot fronds, and the pipes are easy to store when not in use.
I cover the hoops with 3-mil plastic sheeting to create the tunnel. The sheeting is heavy enough to keep out fierce winds and cold during the depths of winter, while still admitting sunlight. On warm, sunny winter days, I open up the ends of the tunnel to release excess heat, and close them up again at night. I weight the edges of the sheeting with bricks or by wrapping them around broomsticks to keep the plastic from whipping up in high winds.
This simple system works extremely well. One December, I was actually bitten by a mosquito while harvesting crops inside a mini hoop tunnel! Occasionally, a snail survives a few weeks inside the tunnel, nibbling away at the tops of the roots. I simply trim off that damage before eating the carrots. If insect damage bothers you, or you fear losing your crop to rodents, you can always harvest your frost-sweetened carrots and store them in buckets of damp sand placed in a cellar or other cool, frost-free place.
How Low Can They Go?
Generally, carrots are very cold-hardy and can withstand some pretty low temperatures if they’re left in the ground and protected. I’ve never had protected carrots in the garden freeze and thaw into a slimy mess — even in temperatures as low as minus 10 degrees for a couple of nights. If you live in a very cold climate, though, there are tricks to boost the temps inside your cold frame or low tunnel. Snow is a great insulator. I’ve shoveled 6 to 8 inches of snow on top of flat-lidded cold frames just before a bitter cold front moved in, and had great luck keeping the carrots fresh underneath. I also toss old throw rugs on top of the cold frame on especially frigid nights. For more direct insulation, you can cover the carrots with a deep layer of straw mulch. Some people run extension cords out to power incandescent light bulbs in their cold frames; the bulbs provide enough warmth to offset bitter temperatures. Another technique is to place black-painted plastic jugs of water at the back of the cold frame; they’ll absorb heat all day and radiate it back into the cold frame at night. Suspend a second layer of heavy-duty plastic sheeting about 2 inches above the first to add protection to mini hoop tunnels; this buffer is the equivalent of moving your garden another growing zone south.
The Roots of Your Labor
I usually begin harvesting frost-sweetened carrots from my garden around Thanksgiving, so I can brag about them to friends and family on the holiday weekend! Harvest continues even after winter has cloaked the garden, but never on bitterly cold days. It’s best to wait until the sun is shining or temperatures have risen, to avoid releasing the stored heat from your tunnel or frame when it can’t be replaced. If there’s a cold snap in the forecast, I harvest enough to last my household until temperatures have moderated.
Carrots’ growth will pick up as the days get longer and they’re exposed to more sunlight. I usually harvest all of my roots by early February because they get stringy and woody as they grow again. Plus, by then, I’m thinking about getting the bed ready for spring crops.
Once you become accustomed to frost-sweetened carrots fresh from the winter garden, you won’t want to waste your taste buds on the bland roots in grocery stores. They’re easy to grow and mostly pest-free — especially in late summer and fall — so give them a try in your next fall garden.
Growing Great Carrots
• Carrots need a sunny site and deep, loose soil with a fine, friable surface. If that doesn’t sound like your garden, consider building a raised bed. Add 2 to 3 inches of compost. Avoid high-nitrogen fertilizers, which can cause roots to fork or become hairy.
• Sow carefully to reduce thinning later. Make shallow trenches, spacing the seeds every 1/2 inch and rows 8 to 10 inches apart. Cover lightly with soil, and water the bed. Keep the soil evenly moist until the seeds germinate (1 to 2 weeks).
• When the seedlings are growing well, thin them to 2 inches apart. Continue to pull every second root as the carrots grow. This allows the remaining ones to thicken up. Don’t forget to eat the seedlings!
• Soak the bed weekly to encourage steady growth, and weed regularly.
• Keep an eye out for pests such as slugs and snails. Use diatomaceous earth to discourage them. Deer also love carrot greens; deter them with a barrier.
• Use mulch to hold in soil moisture and prevent green shoulders.
• Wait to harvest until cold weather has turned the starches in the roots to sugar. You can also eat carrot tops raw or cooked. They’re bitter, but you can blanch them to temper the bitterness, and then stir-fry with garlic and olive oil.
Rebecca Martin is an editor at Heirloom Gardener, and an avid proponent of growing your own vegetables as close to year-round as possible.