Sowing Carrots The carrots from a seed tape I received as a gift have germinated much better than the ones I pre-germinated in damp sand earlier. (Can anyone explain this? My seeds were new, too.) But: despite surprisingly little snail pressure so far, more and more seedlings are disappearing, while the marigolds next to them remain untouched. From this, I conclude that the slugs aren’t to blame. There are no visible signs of birds scratching around, but I can’t think of anything else. So my question is: how long do you keep your carrots under fleece or something similar after they’ve sprouted?