The link below is full of information. I'm going to try to get raised beds in for carrots this year. I use pelleted seed so that I don't have to thin them much.

Here is a link that might be useful: Growing Carrots

I don't know, you'd think they'd do well in your raised bed with good soil. How far are you spacing them? Watering enough? They do take a while to grow in the spring, seem to grow faster when planted as a fall crop in July.

Good link Robin, great info.

assuming you are seeding them at the correct depth, the thing i think is most problematic is germination. i cover my bed with 1 layer of burlap and anchor it. i keep the burlap damp... don't let the soil beneath dry out. carrot seed is hard to germinate. depending upon air and soil temps this will take 5-21 days. once you see the seeds have started to grow into the burlap carefully remove it (you need to check every day tho it's just a 20 second look-see). then i'd be pretty careful to keep them watered if it's hot or just dry. i don't fertilize them but do make sure they get enough water all season. best to grow in full sun. hope this is helpful.

tom

The 3 best thing I did for my carrots were to add sand to the bed, cover them with reemay to keep seeds from washing away and to keep the wireworms out, and remember, it is a root crop so you need to fertilize/ammend it as such.
Martha

It says that cold weather can make carrots thin and that acidic soils are bad for carrots..... that's probably what you have in Maine right? Maybe you could amend with something "alkaline" :)