Among my collection I have a pot containing some Danvers half-long carrots and some kohlrabi that I started from seed. The little guys germinated well and I was very excited. But almost a month later, they've only gotten slightly taller than they were a few days after they came up, and they have no new leaves.

I have them next to a window where they get at least 5 hours of bright (but indirect) light a day. The kohlrabi is looking a little leggy, so I'm tempted to say that this is a light issue, except that all the plants I have that weren't started from seed (including some beets I regrew from supermarket roots) seem perfectly happy under the same conditions. I'll buy a grow light if necessary, but I wanted to check what you guys think first.

Could it be a crowding issue? The plants are about 1/4 inch to 1 inch apart. I also have them on a heater to counter the draft from the window, could that be the problem? I've had similar issues with other seeds before, but I didn't think much of it because I wasn't really serious about growing those.

I recently pulled up one of the carrots to make room for another seeding (kailaan) that I wanted to put there, and I didn't notice any notable root development. What do you think?