Yesterday afternoon and this morning, Rich and I hilled our potato plants for the first time this year. We had a good crop last year, so we're doing the same method this year: first hilling with compost and second hilling with straw. When the plants are around 6" tall, we pile compost along the rows around the plants, covering them about halfway up, making sure not to bury them. In another few weeks, we'll do the same with straw. This gives more loose cover for the tubers to develop in and stay out of the sun. If the tubers are exposed to light, they turn green from chlorophyll, but they also develop solanine, which is a mild poison, as a natural defense to being eaten by animals. So it's generally recommended to not eat potatoes that are green below the skin. To do all six 48'-long rows, we used 380 buckets of compost. It's hard work (each bucketful of compost weighs 35+/-lbs., so that's 13,300 lbs. of compost loaded, hauled, dumped, and spread), but we think it's worth it. Not only does it make a great hilling medium for the potato plants, it's also an excellent weed barrier, and next year, the soil will have that much more organic matter in it.