As a homesteader and gardener, I know that potatoes are one of the most versatile and nutrient-dense crops you can grow. They store well, taste great, and can be prepared in dozens of ways. But before you get to eat those delicious homegrown potatoes, you first have to grow them – and that starts with high quality seed potatoes.
One of the keys to getting your potato crop off to a strong start is knowing how to properly cut cure and store your seed potatoes. Cutting seed tubers stresses the potatoes, increasing the chances of disease and rot setting in. So you need to handle cut seed potatoes carefully to preserve their viability. Just how long will cut seed tubers last before planting? What’s the best way to store them to maximize shelf life? In this article, I’ll share everything I’ve learned over the years about how long cut seed potatoes will last.
Why Cut Seed Potatoes in the First Place?
Before we get into proper storage and handling let’s review why we cut seed potatoes rather than planting the whole tuber. Cutting seed tubers into smaller pieces allows you to get more “seedlings” from each potato. More plants per seed potato equals more yield potential! Cutting also creates more evenly sized seed pieces helping ensure uniform sprouting and growth.
- Whole small tubers (1.5-3 oz) can be planted without cutting. But larger tubers need to be cut into blocky chunks roughly 1.5-2 ounces each.
- Each chunk should have at least 1-2 eyes to sprout.
- Professional potato cutters aim for 70% of seed pieces between 1.5-3 oz. The average is around 1.75 oz per piece.
Curing Newly Cut Seed Pieces
Once cut seed potato pieces need time to heal and “cure” before planting. This curing period allows the cut surface area to develop a protective barrier and avoid rotting. Proper curing also helps overcome dormancy and promote vigorous, even sprouting.
- Ideally, freshly cut seed potatoes should cure for 1-2 weeks before planting. The exact curing time depends on the potato variety, their physiological age, and whether they’ve already started sprouting.
- Young seed potatoes cure faster than old seed.
- Seed that’s sprouted needs less curing time, only 5-7 days.
- Middle-aged seed tubers cure for 7-14 days.
- Older seed or varieties prone to dormancy (like Atlantic or Kennebec) need the full 2 weeks.
- During the curing period, cool the cut seed potatoes to 38-40°F with 85-95% humidity. Good airflow prevents CO2 buildup but avoid drying the seed out. After curing, cut seed can be held for planting up to 4 weeks if properly handled.
Handling Cut Seed Potatoes for Maximum Viability
The key to maximizing how long cut seed potatoes last is being gentle! Rough handling causes bruising, which invites rot and decay. Here are my tips for keeping cut seed potatoes in top shape:
- Store cut seed in shallow trays, 6 inches deep max.
- Avoid dropping pieces or throwing them around. Impact damages cut surfaces.
- Transport seed carefully to avoid knocking piled seed together.
- Keep seed cool (38-50°F) but allow 2 days to warm up before planting.
- Maintain proper humidity around 85-95% to prevent drying out.
- Apply seed treatment as a safeguard against disease organisms.
- Warm seed tubers before taking them from storage to avoid condensation.
Follow those handling guidelines and cut seed potatoes can last 4-6 weeks in proper storage. Gradually warming the seed for planting 2 days ahead helps too.
However, cut seed viability declines over time. After 6-8 weeks, chances of rot and weak sprouting go up. I try to avoid cutting seed more than 1 month before planting if possible. For best results, cut seed potatoes 1-2 weeks before planting day.
Watch for Signs of Trouble
No matter how carefully you handle cut seed potatoes, issues can still creep up. Keep an eye out for these warning signs that indicate your cut seed isn’t storing well:
- Shriveling or wrinkling – seed is dehydrating
- Mold or soft wet spots – disease setting in
- Sprouts drying out or weakening – seed aging
- Greening of the cut surface – exposure to light
- Stuck together seed pieces – lack of air circulation
If you notice those problems in your cut seed potatoes, isolate and discard the damaged pieces. Cut and cure a fresh batch of seed tubers as needed. Letting diseased seed go into the ground will lead to a weak crop plagued by disease.
Key Takeaways on Cut Seed Viability
To sum up this article, follow these tips for maximizing how long your cut seed potatoes will last:
- Cure freshly cut seed 1-2 weeks before planting
- Handle seed gently to prevent bruising
- Maintain proper storage temperature and humidity
- Allow 2 days to warm seed tubers before planting
- Watch for shriveling, mold, and other warning signs
- Discard severely damaged seed pieces
- Plant cut seed potatoes within 1-2 months for best viability
Curing cut seeds before planting and carefully handling cut tubers are key to preserving viability. With proper storage methods, cut seed potatoes can last 4-6 weeks. For best results, plant cured cut seed within 1 month. Follow these guidelines and you’ll get your potato crop off to a healthy start!
Bulletin #2412, Potato Facts: Selecting, Cutting and Handling Potato Seed
By Steven B. Johnson, Ph.D., Extension Crops Specialist, University of Maine Cooperative Extension
For information about UMaine Extension programs and resources, visit extension.umaine.edu.Find more of our publications and books at extension.umaine.edu/publications/.
Table of Contents:
Selection of good seed is a critical decision faced by every potato grower. A good crop starts with good seed. The same amount of fertilizer, pesticide, and effort is put into a crop from poor seed as into a crop from good seed. Choosing seed that is both physiologically as well as physically healthy is important. Disease-free seed is essential to a good crop. Seed that is physiologically young, has been handled gently and stored carefully is also important.
Curing Cut Potato Seed
Cool the cut seed to 38 to 40 degrees F (<45 degrees F), and do not pile it more than six feet deep. Good air circulation will keep the temperature uniform and prevent carbon dioxide buildup, which interferes with wound healing. Relative humidity levels of 85 to 95 percent are needed to promote healing and prevent dehydration.
Six to 10 days at these conditions will complete the curing process. If there is too much air flow and not enough humidity, a thin skin may form on the cut surfaces. This thin layer is not enough to provide wound protection and can be easily sloughed off when handled.
Warm the seed tubers before taking them from storage, unless sprouting is a problem. Re-warm seed again for two days before planting to get sprouts growing again and to avoid condensation on the seed. Remember that this practice does not overcome deficiencies of poor quality seed.
Chemical seed treatment is often used as insurance against disease. Chemical seed treatment is recommended if seed is to be planted in very wet, very dry or very cold soils. Seed-piece treatments with a ground tree-bark component appear to aid in wound healing and prevent cut pieces from sticking together. This provides a better flow of seed at planting. One pound of seed treatment material per 100 pounds of cut seed is too much, one-half pound of material per 100 pounds of cut seed is not enough.
How To Cut Seed Potatoes
FAQ
How long can cut potatoes sit before planting?
A less risky practice is to put about 5 pounds of cut potatoes into a large grocery bag and fold the top closed. Keep the bag at room temperature for 2 or 3 days, then shake the bag to unstick pieces that may have stuck together. Let sit for another 2 to 3 days and then plant.
How long can seed potatoes be stored before planting?
-
YouTube · Erica’s Little Welsh Gardenhttps://www.youtube.comHow To Save Seed Potatoes From This Years Harvest To Grow Next …Sep 3, 2020 — and all of my. all of my seed. potatoes. so actually now you know we’re um at the beginning of September. now so they’re only really going to need to…
-
Organic Potato Projecthttps://organic-seed-potato.russell.wisc.eduHandling seed potatoesMar 9, 2015 — However, if you just received your seed spuds in the mail, it’s ideal to store them at 50 – 55 F with high humidity for a week or two. … Let the tu…
-
Southern Exposure Seed Exchange Bloghttps://blog.southernexposure.com6 Easy Steps to Save Seed PotatoesSep 30, 2021 — Proper Storage Ideally, you should store you potatoes somewhere dark where temperatures remain between 35° and 40°F though they will still keep for …
-
Gardening Know Howhttps://www.gardeningknowhow.comTips On Saving Seed Potatoes For Planting Next YearJan 26, 2022 — How to Save Your Own Seed Potatoes. Your seed potatoes will need a rest period before planting. The rest period induces sprouting, but improper stor…
-
Idaho Potato Commissionhttps://idahopotato.comHow Long Would Seed Potatoes Last Before Planting? | Idaho Potato Commission
-
Veseyshttps://www.veseys.comIrish Cobbler Potatoes – Vegetables | VeseysUnder the ideal storage conditions, potatoes can remain fresh for 3 to 6 months or longer. Sprouted potatoes can be planted in spring, if they look healthy, and…
Does cutting seed potatoes increase yield?
-
Increased Seed Stock:Cutting potatoes allows you to plant more plants from the same amount of seed, essentially stretching your seed potatoes.
-
More Plants, More Potatoes:Each cut piece with a bud or “eye” can develop into a new plant, potentially leading to a higher total potato harvest compared to planting only a few whole potatoes.
-
Yield per Cut Piece vs. Whole Potato:While a whole potato may yield slightly more per plant than a cut piece, the overall yield from the same seed stock is higher when cut and planted.
-
Proper Cutting:Ensure each cut piece has at least one eye or bud, and allow the cut surfaces to dry and “cure” (form a protective layer) before planting.
-
Considerations:If you have ample seed potatoes and space, planting whole potatoes may be a better option, as they tend to produce slightly larger tubers, says a Reddit thread.
Can seed potatoes be too old?
Should grow fine, however the seed/tuber might yield only small potatoes as it is physiologically old seed. If you want to grow bigger potatoes, younger seed should be planted as long as it has broken through its dormancy.