Carrot Plant Profile

Organic Carrots
Kevin Summers/Photographer's Choice/Getty Images

Growing carrots (Daucus carota)—or any root vegetable, for that matter—can be a bit of a gamble since you can't see how well they're doing until you harvest. Even experienced gardeners can have trouble growing long, sweet carrots. Very often, carrots can disappoint with bland, misshapen, tough roots. But given loose soil, some cool weather, and plenty of water, there's no reason you can't grow sweet, crunchy carrots.

Carrots are biennial vegetables, though they are typically harvested in their first year of growth, before they overwinter and set flowers the following year. Carrot foliage is finely dissected, with fern-like compound leaves. Carrot flowers have five petals and sepals, and are born in compound umbels. Most roots are about 1 inch in diameter and anywhere from one inch to more than 12 inches long. Carrots are best known for long, orange roots, but they actually come in several colors and shapes.

Carrots can be planted from nursery-grown seedlings, but the more common method is to sow seeds directly into the garden, beginning as soon as the soil is workable in the spring. The seeds will germinate in 10 to 21 days. From seed to harvest typically takes 50 to 75 days. Even if left in the ground into winter, the roots can still be quite delicious.

Botanical Name Daucus carota
Common Name Carrot
Plant Type Vegetable
Size 6-in. root, 1-ft foliage height; 9-in. spread 
Sun Exposure Full sun to part shade
Soil Type Loose, well-draining soil
Soil pH Slightly acidic (6.06.8)
Hardiness Zones 3–10 (grown as an annual)
Native Area Europe, Southwestern Asia
Toxicity Foliage may cause skin irritation

How to Plant Carrots

Carrots grow well in cool weather. You can begin planting carrot seedlings or sowing carrot seeds as soon as the soil can be worked in the spring, even two to three weeks before the last frost. You can succession plant carrots every couple of weeks throughout the spring. In warmer climates, you may have better luck growing carrots in the fall, through the winter.

Carrot seeds are tiny, making it difficult to plant them evenly. Sprinkle the seeds in a row and cover them barely with no more than 1/4 inch of soil. They may take as long as three weeks to sprout. When the seedlings are 1 to 2 inches tall, thin them out to a spacing of 1 1/2 to 2 inches. Snipping or pinching the seedlings off at the soil line is the best way to avoid hurting the remaining roots.

To prevent the soil from crusting over and making it difficult for the seeds to sprout, you can plant the carrot seeds with radish seeds, which will sprout first and loosen the soil.

To prevent deformed roots, keep the area free of weeds as the carrots are growing. If you need to thin again later, you can use the tiny carrots in salads. When you've finished thinning, your carrots should be far enough apart that they won't rub shoulders when mature.

Carrot Care

Light

Even though the roots are growing underground, the foliage needs full sun to part shade for the carrot roots to grow quickly and develop their sugars.

Soil

Carrots need loose, well-draining soil. Rocks and clumps will cause the carrot roots to split and deform. Growing carrots in raised-beds with fluffy soil is the ideal situation. Carrots prefer a slightly acidic soil—in the range of 6.0 to 6.8.

Water

Water your carrots with at least 1 inch of water every week. Mulching will help conserve water and keep the soil cool.

Temperature and Humidity

Carrots can be grown just about anywhere, even indoors. These biennials are typically grown as annuals in all zones and in all climates. However, they grow best and are tastiest when nighttime temperatures average about 55 degrees Fahrenheit and daytime temperatures average 75 degrees. In warmer climates, carrots are sometimes planted as a late fall and winter crop.

Fertilizer

If your soil is not rich in organic matter, supplemental feeding will be necessary about two weeks after the carrot tops emerge. Any good vegetable fertilizer will do. Because they are grown for their roots, don't go overboard with nitrogen fertilizer, which mostly aids foliage growth

Are Carrots Toxic?

The foliage of carrot is edible and is sometimes used in salads, but it also contains a substance known as furocoumarins, which can cause skin irritation.

Carrot Varieties

There is a seemingly endless number of carrot varieties in an array of sizes and colors. Some notable varieties to try include:

  • 'Danver's Half Long': early, sweet, and easy growing
  • 'Imperator': a long variety that keeps its sweetness and crunch in storage
  • 'Little Finger': a sweet three-inch "baby" carrot
  • 'Paris Market'/'Thumbelina': plump, round, and bite-sized

Harvesting

When to harvest your carrots will depend on the variety you are growing, but the average is about 50 to 75 days from seed. Use the days to harvest on your seed packet as a guide for knowing when to start picking. Test to see if the tops of your carrot plants have filled out to the expected diameter by feeling just below the soil line. The only true test is to lift one of the carrots and taste it.

Don't try and harvest too soon, thinking you will get sweet baby carrots. Small carrots in the store are either a particular variety that matures small or large carrots that have been ground down to baby-size. Immature carrots will be bland because they have not had time to develop their full sweetness.

If your soil is very soft, you can twist and pull the carrots from the soil. To be on the safe side, it is wise to loosen the soil sightly before harvesting, making sure not to stab the carrots in the process. Remove the leaves immediately after harvesting. The leaves will continue to take energy and moisture from the roots, leaving them limp and lessening the sweetness of your carrots.

Common Pests and Diseases

The biggest pest is the carrot rust fly. It lays its eggs in the soil near the carrot top. When the eggs hatch, the larvae work their way down into the soil and then into the carrot's roots, where they feed and create tunnels through the carrot. Carrot weevils can do similar damage. You can foil some pests by rotating where you plant each year, but the easiest method is to grow your carrots under row covers.

Nematodes, microscopic worms, can become a problem later in the season, causing badly deformed roots. Heating the soil through solarization can kill nematodes. If you are struggling with carrot nematodes in a particular spot, rotate to another crop and plant carrots elsewhere.

Even if they don't notice the roots growing below the soil surface, there are plenty of animals that will want to eat the tops of your carrots and a few who will dig deeper. Deer, groundhogs, rabbits, opossum, and several others will need to be kept out of the garden—fencing is really the only effective method.

There are a handful of leaf spot and bacterial diseases that can affect carrots, like Alternaria leaf blight, carrot yellows, and bacterial soft rot. There is not much you can do once the plants are infected. Keep a close watch and remove any plants showing signs of disease. Clean up all debris at the end of the season and move your carrots to a different section of the garden next year, as the microorganisms can persist in the soil.

How to Grow Carrots in Pots

Carrots require loose well-drained soil. They will fork and deform if they meet with the slightest resistance, such as a rock or hard soil. If you can't provide loose soil in your vegetable garden, consider growing carrots in a container. The shorter finger-types or small round carrots, like 'Paris Market', are ideal for containers. Make sure your container is at least 12 inches deep.