carrot and parsnip seeds can be very slow to sprout and very picky about sprouting in hard soil. Plant some radish seeds along with your carrots and parsnips. The radishes will sprout quickly, marking the row and loosening the soil for the carrots and parsnips to break through. The radishes will be harvested long before the carrots and parsnips need the room to fill out. Just be careful you don't pull them out along with the radishes.