Potatoes are grown from certified seed potatoes
Potatoes are grown from certified seed potatoes (disease-free seed tubers from a certified source). Don't plant saved tubers or grocery-store potatoes. Large seed tubers are cut into blocky pieces, each with at least one eye, and the cut surfaces left to dry to a tough protective skin before planting. Grocery-store potatoes may be treated to stay dormant and can carry disease that persists in the soil.
Promising A person has checked it against its sources. If you skip this, it still grows, just less well. The planner suggests it.
How it works
Potato is propagated vegetatively (the crop grows from a piece of tuber), so any virus or disease in the seed tuber is passed straight to the new plants and can remain in the soil for years; certified seed is inspected, disease-free stock, which is why saving one's own tubers or planting grocery potatoes risks introducing disease. Each planted piece must carry an eye, the bud the new shoot grows from. A freshly cut piece exposes moist flesh that storage and soil rots colonise; holding the cut pieces a few days until the surface dries and forms a corky protective layer (suberises) seals that wound before planting. Grocery tubers may additionally be treated with a sprout inhibitor, so they are slow to grow.
What to do about it
Buy certified seed potatoes. Cut large ones into blocky pieces of about two ounces, each with at least one or two eyes; leave small tubers whole. Spread the cut pieces at room temperature (about 60-70 °F) for a few days until the cut surface has dried and formed a tough skin, then plant. Do not plant grocery-store potatoes (possible sprout inhibitor, and disease that lingers in the soil) and do not replant your own saved tubers year to year (virus and disease build up).
How much it matters: No figure is stated. The sources give a seed-piece size (at least about two ounces, one or more eyes) and a curing window (a few days at 60-70 °F until the cut face toughens); the harm from uncertified, grocery, or saved seed is disease introduced into the soil where it can persist, stated without a quantified loss. Because the seed source and handling are entirely the gardener's to control, the rule only advises.
The evidence
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
Buy disease-free seed tubers from a certified grower or seed distributor
When buying seed tubers, ask for certified seed as this will help reduce the potential for introducing disease into the garden
Plants it applies to
Read next
- Growing potatoes from seed tubersThe potato (Solanum tuberosum) is a nightshade, kin to tomatoes and peppers, grown from pieces of tuber instead of seed. That decides most of how you grow it.
- Saving seed that comes trueTomatoes, peppers, beans and peas come true from saved seed. Squash, corn and the cabbages will surprise you. Which is which, and how to clean, dry and store seed.
How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Wording made clearer
- Added to the rules
Cite this page
Milpa Gardens. "Potatoes are grown from certified seed potatoes (disease-free seed tubers from a certified source). Don't plant saved tubers or grocery-store potatoes. Large seed tubers are cut into blocky pieces, each with at least one eye, and the cut surfaces left to dry to a tough protective skin before planting. Grocery-store potatoes may be treated to stay dormant and can carry disease that persists in the soil." Evidence grade: Promising. https://milpa.garden/rules/potatoes-grown-from-certified-seed-potatoes-disease/
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