Kenosha Potato Project

Potato Seed Storage (tubers, not true seed TPS)

This page is linked to the Kenosha Potato Project web pages. See these links for


This page reports on our experiments for proper potato storage by our network of local gardeners.

Curing of tubers first occurs in the soil - harvest potatoes 2 weeks after the vines have died down naturally. The soil is the best storage place! I have harvested tubers in January (if we have a crazy winter - like 2008 with 70 degrees days in January) ... but usually you can delay the harvesting to November - December, before heavy snow falls and/or hard freezing of the soil.

The basics of potato storage are: darkness and high levels of humidity (up to 98%) - the old farm houses' Root Cellar is the perfect storage place. Most home gardeners don't have a root cellar (a non-heated basement room without pavement - open to the earth humidity).

Creating the perfect storage place for potato seed:


As the curator of the Kenosha Potato Project I felt compelled in creating the perfect storage place for hundreds of cultivars. I have a storage shelter outdoors which is insulated to control the temperature. A heating element on a thermostat kicks in at 32F and shuts off at 41F. Potato tubers are not frost damaged in the soil, but in storage they may be damaged at temps below 30F.

Challanges of outdoor storage are high humidity levels and critters, particularly voles. I have wrapped my storage shelves with tight-knit hardware wire to keep voles out, and with plastic to keep humidity in. A humidifier produces a mist of moisture that should keep the humidity high - 98% optimal. I'm using an AirKing 9929 which features a humidity indicator - by setting the desired humidity at 90% the fan works all the time and I achieve about 86 - 88% and need to add about 2 gallons of water per week. The 4.5 gallon capacity reduces the chore of refilling to once a week.


Keep in mind that apples, onions and potatoes CANNOT be stored together! If you need to store all staples in one room, you need to build separate shelving with plastic wrapping to enclose humidity and vapors (apples emit ethylene vapors). The refrigerator is good only for onions due to low humidity requirements. Opposite for potato tubers you need high humidity.

Also, keep in mind that below 45F potato tubers change starch to sugar, which does not affect the viability of the tubers as seed, but make the spuds less palatable as food. You can store your food supply potatoes with your seed potatoes at cooler temperature - if you need potatoes for food, just bring them in the heated pantry for 2 weeks and the sugars will revert back to starch.

Keep in mind that potato tubers start sprouting at temperatures above 50F, therefore you want to keep them in cool storage. If you can achieve a lower temperature for your seed tubers, it will be easier to keep the humidity high, and likely the tubers quality will be higher for a longer time - first week of April is our target planting time.

Some cultivars "store" better than others

This is a list of pictures of my selections ... cultivars which stored very well without refrigeration.

This year in August I still have tubers from last year. Ozette, Indian Tinglit and Cranberry Red.

Best storage winner of 2008-09 is Cranberry ... in July it still had no eyes' growth. Second best Indian Tlingit; third is Ozette, which still tastes fantastic but the skins look more dehidrated.

This picture shows a tuber of Indian Tinglit harvested in August 2008, stored without refrigeration for 12 months.

Some varieties don't spoil in the soil

This picture shows two tubers of Cranberry Red that I found when I harvested my 2009 crop. The small, bright red tuber is part of the 2009 crop, while the pale red tubers are the seed pieces that I've planted in the spring.

The seed pieces are no longer edible - the taste and texture are not palatable.

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web page updated: August 16th, 2009
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