Where should I get my seed potatoes from? Gardeners should buy certified seed potatoes from their local source. Potatoes from the supermarket should not be used because they may carry diseases or be treated with a sprout inhibitor that can prevent the tubers from germinating.
How do I prepare the seed potatoes? Potatoes should be cut so that each seed piece has at least two eyes; each piece should weigh at least 1.5 ounces (about the size of a small egg). Make cuts to expose the least amount of surface area. During cutting, discard any potatoes that show dark rings or discoloration inside. Seed pieces should be planted immediately after being cut. If weather delays planting, cut seed may be stored for a few days at 55º to 60ºF. To promote surface healing of the seed pieces, high humidity (85 percent) is recommended. Gardeners can get a jump on production by per-sprouting their potatoes. To sprout seed potatoes prior to planting, place them for two to three weeks in a single layer on an enclosed porch or in a warm room where they will get some sun and where the temperature will stay at 600F or warmer.
What varieties do I need to plant? The variety you choose depends on your personal taste. Some of the white Irish potato varieties include Kennebec, and Irish Cobbler. Early red varieties are Red Pontiac and Red LaSoda. The thick, russet-skinned potatoes sold in the grocery store do not grow well in the South and should be avoided.
When should I plant potatoes? Gardeners can plant early potatoes when the soil temperature reaches 45ºF, usually before the danger of the last spring frost has passed. The Georgia Weather Network is a great place to monitor soil temperatures and frost dates. Potatoes germinate and emerge best when soil temperatures are above 50ºF.
How deep and how far apart do I plant my potatoes? Plant seed potatoes 4 to 5 inches deep with the eyes facing up. Gardeners can space their rows 24 to 36 inches wide and plant potatoes 7 to 8 inches apart in the row. Although potatoes can be planted on flat ground, forming a hill around the plant is preferable. Hills provide room for developing tubers to expand and prevent greening from the sun. Potato hills can be formed at planting time by mounding dirt around the seed piece, or they can be formed after the plants are up. Hill within four weeks of planting.
How do I fertilize my potatoes? The best soil acidity range for potatoes is between 4.8 and 5.4 pH. On soils with a pH of 5.5 to 7.0, the potatoes can be infected with a disease called scab. Lime should not be used unless a soil test indicates a pH level below 4.8. Gardeners should broadcast 10-10-10 at a rate of 1.5 pounds per 100 square feet when forming hills before planting; then side dress about 6 weeks after planting when tubers begin to form with another application of 10-10-10 at the same rate. Additional fertilizer can be added up to three weeks before harvest.
What about irrigation requirements for potatoes? Water is critical when blossoms are forming and should be added if the soil at this time is dry.
When are they ready for harvest? Dig your potatoes when the tubers are large enough to eat. Potatoes are ready for harvest when plants begin to decline. When plants begin to turn yellow and fade, carefully dig potatoes with a shovel or pitchfork, taking care not to puncture the tubers. After harvest, spread the potatoes on dry ground for several hours to allow them to dry off. Do not wash potatoes until just prior to use, as this will cause them to rot. Store potatoes in a dark, cool place, out of direct sunlight.
A great resource for home garden potatoes is in the publication Home Garden Potatoes. If you have questions about home garden potatoes, please contact your local county agent.