Sowing more carrots

The carrots that I sowed a few weeks ago have not been a massive success - maybe 4 or 5 have germinated. But I can't see any of the landcress or rocket that I sowed at the same time either. I wonder if they were affected by the very cold snap of weather between the hot spells? Anyway, I thought I'd sow some more, but this time I've put them in toilet rolls ready to plant out when they're bigger. There are a few shoots beginning to show on the kale and mangetout, so I've covered them in netting to keep the birds/mice away.