Early varieties: Will be ready at the end of May through to July, around nine to ten weeks after planting. Flowering is usually a good indicator that the tubers have reached an edible size, but not all varieties produce flowers. Dig up one plant or investigate with a trowel to see if the tubers are ready. They are best harvested as needed, leaving the rest to grow on. Most early varieties are not suitable for long-term storage. Average yield: 5.5kg per 3m row (12lb per 10ft row) Main crop varieties: Depending on the variety, planting date and the growing conditions, these will be ready from mid July through to early October. More at https://www.gardenorganic.org.uk/factsheets/growing-potatoes