The plants are now about 12 inches high and I knew it was time to hill them up. I would recommend hilling sooner than I did but since I planted the potatoes so deeply there was nothing poking through yet.

Potatoes form between the seed piece and the stem of the plant. The deeper you plant the seed potato the more room there will be for your tubers to grow. Hilling potatoes is necessary because as the tubers grow they begin to pop through the surface of the soil which causes the developing tuber to turn green. Green tubers can be toxic when eaten and cause a nasty upset stomach.
I read up on hilling potatoes and found there to be just as many methods for hilling as there are for planting the seeds. Good hilling materials include compost, soil, dry shreded leaves, hay, and straw. Each seems to have it's pros and cons. I did find that most gardeners recommend not using manure to hill since it often causes root rot.
I decided that the easiest way to hill my potatoes would be to use straw. Since I didn't want weeds in the bed I made sure to get a straw product that had been sterilized such as Mainly Mulch.
To keep the straw in the bed Andy screwed some stakes into each corner of the bed and then wrapped the entire bed in plastic garden fencing.
You can use any material to fence the bed in - chicken wire works great too. It doesn't need to be as high as we made our fence (we just used what we had laying around) but it needs to be high enough to contain the hilling material.
Here you can see the plastic fencing we used. It comes in a roll and is easy to work with. It's very inexpensive - we bought it last year at Lowes and had some left over to use here.
Once the fence was up we added the straw and made it sure it was fluffy. One of the problems of using straw is that it can attract pests as well as fungus as it decomposes so it's important to make sure you keep it fluffed up so the air lets it breathe. Packing it down would cause many problems and could reduce yield.

For this first hilling we made sure that we went about 6 inches up the stem. In another few weeks we'll add another 6 inches of straw. I'll keep a careful eye out for signs of disease and pests. Before we added the straw I sprayed the plants with copper fungicide to prevent blight. I also sprayed with Spinosa to ward off any pests. I'll spray both again in about 2 weeks.
