How to plant potatoes

I learned something I didn't expect today about planting potatoes. You don't plant them like any other plant I know of. They start off simple enough.

You dig a 30 cm (12") trench with all the soil piled up on one side, and pop the potatoes in. The BBC website says you plant early potatoes about 30 cm (12") apart with 40-50cm (16-20") between the rows, and second earlies and main crops about 38 cm (15") apart with 75 cm (30") between the rows.

Now comes the strange part. You only fork about 5 cm of soil from your pile back over the potatoes and leave the rest piled up. You then wait until the potato crows about 15 cm above the soil covering it, then fork more of your pile of earth over it until it is covered up to just below the level of its lowest leaves. You then wait for it to grow 15 cm above the soil again, and fork soil from your pile over it until it is covered up to just below the level of its lowest leaves again. You keep doing this (wait for 15 cm of growth then fork the soil over to just below the level of the lowest leaves) until you have no soil left in your pile. This will probably mean that your potatoes end up growing in a little mound of earth by the time you've finished, as replacing all the soil you dug out of the trench on top of the potato plant is likely to put leave you with a mound a little way above ground level. Oh yeah, and don't forget to water them after you've planted them.

Two other things: firstly, you need your potato to chit (that means sprout little green bits) before you plant it - those are going to be its stalk and leaves, so ideally they should face upwards. Secondly, you're wasting your time planting potatoes in September. This isn't the right time to plant them and we planted ours for demonstration purposes only.
Actually, while I'm on the topic of potatoes I learned two other things:
1. The green sprouts they grow are poisonous. Don't eat them, you need to nip them off before you eat a potato if it's chitted (after that you can eat it again).
2. When you harvest your potatoes, you'll almost certainly miss one (or even a tiny bit of one). These are known as volunteer potatoes and will grow again next year. However, because crop rotation is important, you'll be growing other veg in that bed next year, so simply weed the potato out.