This idea is very old, my grandmother used to have straw bale gardens. It was great for her not to have to stoop over to pick and weed her garden. I have done this type of gardening for the past 3 years and had very good results.
You start with Straw bales (not hay) DO NOT cut the strings on the bales. Start with a 2 in layer of organic fertilizer and a 4 inch layer of top soil, pat it all down and try to work it into the straw a little bit, then you plant like you would a regular garden. You do need to water a little more. I use a soaker hose about 30 minutes a day during the hot season. You can also plant marigolds into the sides of the bales to keep away pests.
After a couple of years you will need new bales, the old straw is now starting to degrade and compost so is good for your flower beds or compost it into a regular garden.
By Kalene from Oregon City, Oregon