Carrots and other carrot family crops such as parsley and parsnips can be slow to germinate. They require consistently moist soil and sometimes two weeks or more for germination. Dry or windy weather can mean slow or no germination for carrots.
Carrots, parsnips, and parsley take 14 to 21 days to germinate; that means you must keep the seed bed evenly moist for up to three weeks or longer. This may require near constant attention.
Pre-sprouting is the best way to short-cut carrot germination and insures a crop; there is no guessing whether the seed bed has accidently gone dry and delayed or derailed your crop.
Carrots and carrot family crops are slow to germinate because they have hard seed coats (seed coats or hulls protect seed embryos from decay and deterioration). For seeds to germinate and begin growing moisture must penetrate the seed coat and activate an enzyme triggering respiration and plant cell duplication and growth. Both heat and cold can speed a seed’s intake of moisture.
More carrot growing details at How to Grow Carrots.
Two Ways to Pre-Sprout Carrot Seeds
1. Boiling water method. Sprinkle seed across a tray of sterile potting soil or seed starting mix (you can also use peat moss, peat moss and sand or vermiculite). Pour very warm or just boiling water over the seed. Boiling water removes the cuticle and some lower epidermal layers of carrot seed hulls. Cover the seeds with potting soil or seed starting mix and place the tray inside a clear plastic bag. Mist the soil with a kitchen spray bottle twice a day until the seed has sprouted.
2. Freezing method. Mix the seed with damp potting soil or seed starting mix or peat moss; spread the mix across a seed-starting tray or paper plate. Place the tray or plate in a clear plastic bag, seal it, and set it in the freezer for twenty-four hours but not longer. (This is called cold stratification; placing the seed in the freezer for twenty-four hours is enough for the seed to think it has gone through a winter, but not long enough to freeze and damage cells inside the seed.) Then place the seed and soil mix—still inside the plastic bag (use a large zip lock bag for a paper plate)—on a seed-starting heat mat or refrigerator top or other appliance top at 70° to 80°F for three days or longer—until the seed sprouts.
What to do next. Once seeds sprout, take them out of the plastic bag—soil mix, seeding starting mix, or peat moss and all—and gently set the sprouts in prepared rows and furrows ¼-inch deep then cover them lightly with potting soil. Keep the new sprouts well watered until they are rooted and growing.
The sprouts will grow uniform in height and produce a crop two weeks earlier than if you had sown seed directly in the planting bed.
Most carrot varieties take 70 to 80 days from sowing to harvest. The best time to grow carrots is in the cool times of the year—spring or fall. Fall grown carrots can be stored in the garden bed until you are ready to use them—as long as the soil does not freeze.
More tips: Carrot Seed Starting Tips