Fair test
Growing Potatoes from Store-Bought Potatoes
Growing potatoes from store-bought potatoes sometimes works, but it's a gamble. Many potatoes sold for eating are treated to stop them sprouting, and none are inspected for disease the way certified seed potatoes are. A potato that sprouts well in a jar of water can still grow into a healthy plant, and this page shows how to test one fairly.
Why store-bought potatoes often won't sprout
Potatoes for eating are stored for months, and sprouts make them soft and unappealing, so many are treated with a sprout inhibitor after harvest. In the United States, chlorpropham (often called CIPC) has long been a common one. Organic potatoes can't use it, though they may be treated with an approved natural product such as spearmint oil, or not treated at all. A treated potato may sprout weakly, very late, or not at all.
A freshly harvested potato also has a natural rest period, called dormancy, before its eyes start to grow. Supermarket potatoes are usually past that point, but a potato that won't sprout may simply need more time somewhere warm and bright.
The disease risk
Certified seed potatoes come from crops inspected in the field and in storage, with strict limits on disease. Potatoes for eating have no such checks. They can carry viruses that weaken the plant, and diseases such as late blight, which also attacks tomatoes. In a single Kratky container indoors the risk is small, but don't plant store-bought potatoes in or near a garden where you grow potatoes or tomatoes.
How to test a store-bought potato fairly
- Choose firm, organic potatoes with plenty of visible eyes. They're the likeliest to be untreated.
- Rinse them in plain water. This won't remove a treatment that's soaked into the skin, but it does clean the surface.
- Put them somewhere bright and cool for a few weeks, as you would to chit seed potatoes, or sprout one in a jar of water with the bottom third submerged.
- Keep the ones that grow short, sturdy shoots. Throw away any that stay bare after a few weeks, or turn soft or moldy.
A potato that passes the test can go into a Kratky container just as a seed potato would. See how to grow potatoes in water for moving a sprouted potato into a Kratky container.
Signs of a good candidate
- The eyes are already swelling, or short, sturdy sprouts have started on their own.
- The potato is firm, with no soft spots, mold or green patches.
- The bag names the variety, such as Yukon Gold, so you know whether it's an early or late potato.
- It's organic, which makes a chlorpropham treatment unlikely.
Knowing the variety matters more than it seems. An early yellow or red potato suits a 5-gallon bucket, while an unnamed baking potato may be a late russet that needs a deep tote and a long, cool season. See potato varieties for Kratky growing before you choose a container.
What to expect
Some store-bought potatoes grow into healthy plants and give a fair crop, and some don't. You also won't always know the variety, which makes it harder to plan the container size and the season. A late variety that grows a huge plant, for example, can outgrow a bucket. If you'd like a predictable first crop, start with certified seed of a known early variety, and treat the store-bought potato as a side experiment.
When it's worth trying
- As a kitchen or classroom project, to watch a potato sprout and root.
- When you can't buy seed potatoes out of season and want to grow something indoors now.
- To compare side by side with a certified seed potato of a similar type.
For the safer route, see where to buy seed potatoes.
Questions about planting store-bought potatoes
Can you plant a potato from the grocery store?
Sometimes. Many are treated to stop sprouting and none are inspected for disease, so certified seed potatoes are the safer choice.
Are organic potatoes better for planting?
They're likelier to sprout, because organic potatoes can't be treated with chlorpropham. They still aren't inspected for disease like certified seed.
Can I plant a potato that sprouted in my pantry?
Yes, if it's still firm. Short, sturdy sprouts are a good sign. Long, pale ones are fragile, so handle them gently.
How long should I wait for a store-bought potato to sprout?
Two or three weeks somewhere warm and bright. If it's still bare after that, it has probably been treated.
Does washing remove a sprout inhibitor?
Not reliably. Rinsing cleans the surface, but some of the treatment stays in the skin.
Is it safe to eat a sprouted store-bought potato?
Remove the sprouts and any green parts before cooking, and don't eat the sprouts themselves.
Related Kratky potato guides
More on growing potatoes with the Kratky method, from the first sprout to the harvest.