I know less than the potatoes

So how do seeds know which way to sprout when they're in the soil? Is it gravity? They can't see the light, surely. What is it that a potato knows that I don't?

Answers on thirteen sides of A4 paper please, single spaced.

Made stock and apple pie. Have tasted neither, so I can pretend they're both a success. Achieved absolutely nothing else. Incidentally there is nowhere in this city where one can purchase a pair of regal wellies after 6pm. Disgraceful. I wish to make a complaint.