Growing Organic Potatoes
Growing organic potatoes requires careful attention to soil preparation, choosing early-producing disease-resistant potato varieties, and following good cultural practices, and using natural fertilizers, crop rotation, row covers, and if necessary, the careful application of organic pesticides.
How to Grow Potatoes 05:02
Organic potatoes are grown without synthetic fertilizers or pesticides. Organic seed potatoes – mature potato tubers - are planted in well-drained, moist soil where they will get at least six or eight hours of sunshine. Potatoes grow best in cool weather, neither freezing nor above the upper 80s which reduces tuber production.
Organic Seed Potatoes
Start with organic potato seed from certified organic farms which are easy to find online. Order ahead of time or the varieties you prefer may be sold out. Early-producing varieties can make a good crop before insect or disease problems have a chance to build up. Good varieties to start with include Irish Cobbler, Orla, Norland, Red Duke of York, and Yukon Gold.
Organic seed potatoes can be kept year after year from your own garden, but save only firm, unblemished tubers; those with a little green color, while dangerous to eat, are perfectly fine to save to replant the next season.
Organic Soil Preparation and Fertility
Avoid some diseases by planting in well-drained soils fluffed up with organic matter, such as a green manure cover crop of legumes sown the fall before and tilled into the soil before planting, or adding compost at planting time.
Potatoes grow well in and are less susceptible to disease in acidic soils; natural sulfur can make a soil more acidic. To have your soil pH tested, contact your county Extension office. Note: Many Extension professionals will recommend organic fertilizers upon request.
Potato plants require fertilizer, but too much can cause leggy, disease-prone growth. Add generous amounts of compost, or during planting dig in a small amount of natural fertilizer (there are many on the market) or organic poultry manure. Most gardeners find that a second application of fertilizer, a month or so after planting, helps improve yields.
Plant the Potatoes
A few days before planting, cut seed potatoes into pieces, each with one or two eyes (buds) on them. Avoid problems by allowing the cut pieces to dry indoors for a day or two, and dust with agricultural sulfur to help protect against fungal diseases.
Plant the seed pieces about a foot apart and two or three inches deep in rows, hills, or raised beds or containers (especially where diseases have been found before).
Prevent sunscald, bitter flavor, and tuber greening (which indicates a high amount of a poisonous plant alkaloid called solanine). As plants grow, gently pile soil or thick straw over their lower stems; repeat as needed until six or eight inches of lower are buried.
Potatoes need moisture, but avoid overwatering, and reduce diseases by watering early enough in the day to allow foliage to dry before dark.
Potato Pest Control
Healthy plants resist problems; keep potatoes growing with light feedings and careful watering. Use straw or other mulch to improve soil for better root growth.
Cover plants with “floating row cover” which is a lightweight material that allows in sun, rain, and wind but keeps insects out. Cover plants when small all the way to harvest.
One of the most effective natural insecticides is pyrethrin, made from a flower, which can be used to control aphids, potato beetles, flea beetles, and leaf hoppers. Spray undersides of leaves where the pests are found.
Harvest and Store
Use your hands to dig small, “new” potatoes starting about three months after planting, or wait another month or so before digging larger tubers. Dig carefully to avoid cuts; do not wash, just gently dust off excess dirt. What you don’t use quickly, can be stored for months in a cool, dry, dark place, with regular checking for shriveling or decay.