Some of the less widely distributed ones include Indigo and Maroon.
The taste difference between Purple Carrots and Orange carrots is subtle, very subtle. You shant notice much of a difference in cooking, but when eaten raw purple carrots are a tad spicier, a hint of a pepper taste is sometimes detected - but it's the sweetness of the purple varieties that stands out the most.
Germination - Carrots are notoriously slow germinaters. Anticipate up to 3 weeks. Also anticipate uneven germination over a period of a few weeks.
Direct Seeding is best, not transplants. Begin Planting seeds in early spring, 2 to 3 weeks before last frost. After planting, it's imperative that you keep the upper inch of soil consistently moist until the seedlings emerge. Carrot seeds have a vary hard coat that must be kept moist in order to soften them for germination
Carrot seeds will germinate in soil temperatures as low as 50 degrees, but in the vicinity of 70 degrees is best for quicker germination and less seed loss.
Maturity Varies among cultivars - see seed packets
Color - Varying shades of Purple - Orange and Yellowish Cores
Spacing - 2 to 4 inches apart. This is not always possible when planting seed so plan to thin your carrots as they emerge to attain adequate spacing. Allow them to attain a respectable size before thinning - some of the carrots you've removed should be useable.
USDA Hardiness Zones 3- 11
Full Sun / Light Shade
Carrots are cold hardy and will survive fall chills, let some of your carrots stay in the ground until after the first frost. You'll find that the cool weather increases their sweetness.