Carrot (Daucus carota) Hardy biennial. Sow in the spring in the open ground. Tolerant of frosts. Roots can be harvested and root cellared for replanting and seed crops or left in the ground and mulched depending on climate. Insect pollinated. Easily crosses with wild carrot (D. carota) which will reduce root quality.
There are so many kinds of carrots: white ones, round ones, finger sized, stump rooted, red, orange, yellow and purple ones, very sweet and not so sweet. Those used in Europe for soup and livestock feed, those in Japan for pickling and then those that are great for fresh eating and snacking. If you are growing carrots for seed make sure that you start with a carrot that you really enjoy growing and which does well for you on your soil and in your climate.
Producing seed is a two year process. The first year concentrate on raising your crop for food. At the harvest, select a few of your very best roots and store over the winter at a temperature just above freezing. Depending on where you live that may mean back in the ground under a heavy mulch, in a damp cold cellar in sand or peat or in the vegetable bin of your refrigerator wrapped in a damp towel.
Plant the selected roots in early spring when the ground thaws. The carrots will produce Queen Annes Lace (wild carrot) type flowers in July and in late summer, an ample seed crop.
Many kinds of insect pollinators will visit the flowers, some are known to roam over large distances and may bring pollen from wild carrot which can introduce characteristics that you don't want into your seed crop. Make sure your garden fence isn't bordered by Queen Anne's Lace. Also carrot varieties will cross with one another with ease so unless you want to experiment with developing a new carrot variety, plant only one kind.
The plant family that carrot belongs to is Apiaceae. A characteristic of the group is the particular mass of tiny flowers that it produces know as an umbel. Note how the little flower stalks radiate out from the larger ones. When the seeds begin to form, the umbel will fold inward and it becomes a kind of protective home for the seeds until they turn brown and dry. Watch carefully so that you don't loose the seeds as they ripen or when near-ripe, you can pull the plants up by the root and cover the upper stalks with a loose paper bag, and lay the whole mass on their sides in a protected place like the garage until the seed heads are thoroughly dry. Cleaning small batches of seed will require rubbing the seed heads back and forth in your hands to free the seeds and using strainers or screens of a proper size. Inspect the seed for tiny insects that might cause damage to the stored seed.
Harvest carrots the first year for cream, yellow, shades of orange and purple roots in many forms. The second year in the ground (if you prefer to let them winter over) and you will be rewarded with a great flowering bed of Queen Anne's Lace in White and Lavender shades. You may want to embark on a breeding project to cross colorful carrots with very sweet early maturing snacking types (harvest in less than 60 days), you decide whether it would be best to harvest the carrots or enjoy the flowers.