Carrots need 2 to 4 inches of organic mulch as soon as the plants are big enough, 4 or 5 inches tall. Until then, gently hand pull weeds growing near small seedlings until the carrots are tall enough to be mulched with a 1 to 2 inch layer of organic material, such as chopped leaves, shredded paper, hay or straw. As this mulch layer decomposes over the season it contributes valuable organic matter to the soil. It encourages earthworms, and may even harbor some beneficial insects, such as mites and rove beetles, that prey on garden pests. Mulch discourages weeds, maintains soil moisture, cools the soil, and prevents carrots’ exposed shoulders from turning green. However, keep mulch away from plant crowns (the spot where the leaf stems join the carrot root.) Finely chopped leaves, shredded hay or straw make good mulches.
For more information see Mulching The Vegetable Garden
Carrots need about an inch of water over a week’s time either from rain or your watering. Since carrots get thirsty when the top four inches of their soil is dry, check soil moisture by sticking your finger in the soil under the mulch, or use a simple houseplant water meter. Insert the meter probe 4 inches into the soil and read the moisture level on the meter scale. Be sure to water deeply each time, so that the water penetrates the soil slightly deeper than the carrot root grows. Repeated shallow watering will distort the carrot shape.
Covering the soil between the carrots with an organic mulch of some kind slows moisture evaporation, keeping the soil evenly moist longer. Drip irrigation is ideal for watering carrots. A soaker hose system hooked up to a mechanical or computerized watering timer is very effective for delivering water to the entire vegetable garden.
For more information see Watering The Vegetable Garden
Carrots do not need a rich diet the nutrition available in a garden soil that is rich in organic matter is sufficient for them. A slow acting granular fertilizer sprinkled sparingly into the soil in the spring is helpful, especially if the soil is not yet in great shape. Fertilizers containing quick-acting nitrogen stimulates carrots to branch and form hairy roots. Flavor also suffers.
For more information see Fertilizing The Vegetable Garden
Using Shade Cloth for Carrots
A cover of whisper- light, white polyspun garden fleece encourages carrot seeds to sprout quickly and protects the seedlings from birds, insect pests, and drying winds. Lay a piece of this fabric loosely over the new seed bed and secure it around the edges with rocks or peg it into the soil keep it from blowing off. As the young seedlings grow they’ll push the cloth up easily. Remove the fleece when the plants grow taller than two inches.
Carrots are happiest when the days are warm and the nights are cool, conditions found in the fall. Those planted in the early summer for a fall harvest will do poorly if exposed to too much heat and light in July and August. One way to reduce heat and light is to cover the carrots with shade cloth, at least for the first month or two. Rig the cloth about 6 inches above the plants to allow air circulation. Early morning sun or late afternoon sun is no problem.
Thinning Carrot Seedlings
It is very important to thin carrots at an early stage. Unless they have sufficient room to grow from the outset, they will be distorted and undersized. This means that you must pull up some of the young seedlings periodically to prevent crowding as they all develop. Experienced gardeners thin carrots twice. Thin out the first time as soon as the seedlings have two or three ferny leaves and are about 2 inches tall. Pull out or snip off any that are bunched and crowding each other, so that the sturdiest-looking ones remain at about one inch apart. Then thin some of these a few weeks later, when the plants have developed a tiny orange carroty root, so that the remaining plants are 2-inches apart.