Your soil is probably too hard. Carrots need loose, rich soil. Try raised beds. I grow lots of carrots year round, both outside and in the greenhouse. They blow the crap you get in the grocery store away. I like two varieties from Johnny’s Seeds, Napoli and Mokum. (www.johnnyseeds.com) Johnny’s offers carrot seeds “peletized” with a coating that looks like frosting on a Krispy Kreme donut. This makes the seeds about the size of a BB, so they’re easier to deal with at planting time (and no thinning!)
Thanks for the link!