Fertilization can make a huge difference when it comes to growing and harvesting carrots, however, there are certain times that you should fertilize carrots in order to ensure that they grow to the best of their abilities. Fertilization doesn't always have to take place, only if your soil is lacking in nutrients. If you feel that it is necessary to provide your carrots with additional nutrients, you should only apply fertilizer when the carrots have already penetrated the soil and the tops have reached three inches.
If you are using a granular fertilizer, you should use it in moderation. However, they do work extremely well for this type of plant. You will not want to use a fertilizer that is high in nitrogen, as this will alter the way that the carrots taste. Instead, you should find a fertilizer that has a higher potassium and phosphate content, such as a 0-10-10 or 5-15-15 fertilizer.
Experts suggest that you only use half the recommended dose that its states on the bag. For example, if it calls for 1 1/2 pounds for a 100 square foot area, you will only want to use a 1/2 pound. The reason you want to reduce the amount that you use is because too much fertilizer will result in carrots that are void of taste and that have become forked and hairy. After you have applied the fertilizer, you will want to water the area well. The fertilizer should not sit at the surface of the soil in its granular shape, as it will not penetrate and make it to the plant's roots.
You will want to stray away from water soluble fertilizers, as these generally contain too much nitrogen. If you do not want to use chemicals or fertilizers but want to grow carrots organically instead, simply amend your soil with compost prior to planting.