Potatoes about 34 days after planting. The "seed potatoes" were originally planted in a trench about 8 inches deep; as the tops grew, I filled in the dirt around them. In the past I've tried to get a little too creative with my potato growing; once I tried planting them along with the tomato plants, a reasonable idea until I remembered the potatoes needed to be dug long before the 'maters were ripe. I recently read that the potatoes will form *above* where you plant the seed potatoes, so this time I hopefully got it right.
