Carrots are a fairly frost-tolerant, cool season crop, so they can be planted 2-4 weeks ahead of your last frost date, and in late summer or early fall when temperatures cool back into the 70s. Hot weather will cause poor germination and poor quality roots, so for most gardeners, it’s best to take a break from growing carrots in the middle of summer.
Plant your carrots in a location with full sun, and loose, well drained soil. Amending your beds with some well-aged compost is a good idea, but avoid nitrogen-rich fertilizers, as these will cause excessive leaf growth and “hairy” carrots with lots of little side roots.
To seed carrots, make a shallow trench about ¼-inch deep using a garden tool or your hand, and drop in one seed every half-inch, then lightly cover the row over with soil. Don’t compact the soil! Carrot seedlings are delicate. Plant rows 12 inches apart. Make sure to water well after planting and keep the soil consistently damp but not soggy. Carrot seeds are slow to germinate, so don’t worry if your seeds take 10 days or more to sprout. It can take up to three weeks in cold weather. Once your carrot seedlings are up and have their first adult leaves, thin them to 1 to 3 inches apart.
To care for your carrot plants, keep the soil moist throughout the growing season. Mulching around the seedlings as they grow can help keep the soil moisture consistent, while also keeping weeds down. Be very careful weeding around your carrots - pull weeds gently, by hand, to avoid disturbing the carrots’ fragile roots. Harvest when the carrots reach ¾ to 1 inch in diameter and the shoulders start to push out of the soil, usually 2 to 3 months after planting. Loosen the soil around the roots with a garden fork before pulling them to avoid breakage.
Carrots (Daucus carota) are an insect-pollinated biennial. To save pure seed, your carrots will need to be separated from other carrot varieties as well as Queen Anne’s Lace (which is the same species as carrots) by at least 800 feet to avoid cross pollination. Carrots flower in their second season after overwintering. If you are growing in a location that does not usually experience frosts below 15 degrees F, you can overwinter carrots in the field under row cover. If you regularly get temperatures of 15 degrees or lower, you should pull your carrots and store them. To overwinter carrots in storage, brush the dirt off them but don’t wash with water, then cut back the tops to just above the crown, being sure not to remove the growth tip. Store the roots packed in clean sand or wood shavings in a cool location. Once the soil becomes workable in spring, replant your carrots 6 to 18 inches apart with the crown just above the soil line. Once the flower stalks emerge, it’s a good idea to stake them, since they get quite tall and can fall over. Harvest seed heads as soon as they turn brown and bring them indoors to dry for another two weeks before separating the seeds from their pods by rubbing the heads with your fingers over a container. Store the seeds in an airtight container in a cool and dark location.