What Is A Seed Potato? (3 Things You Should Know)

When you read up on planting potatoes, you start to hear about seed potatoes. It helps to know what they are and how they can help you to get a better potato harvest.

So, what is a seed potato? A seed potato is a potato that you bury to grow a new plant. Any potato has the potential to grow into a new plant. However, certified seed potatoes are disease-free and never treated with sprout inhibitors. You can cut a seed potato into pieces (around 2 ounces per piece) to get more plants.

Of course, seed potatoes are not the same thing as potato seeds – even though they sound similar.

In this article, we’ll talk about seed potatoes and how they are different from regular potatoes. We’ll also answer some common questions about buying, storing, preparing, cutting, and planting seed potatoes.

Let’s get started.

The Complete Guide To Growing Potatoes

A complete reference and an ultimate guide that teaches you everything you need to know about potato selection, planting, care, harvest, and storage.

Buy Now

Learn More

What Is A Seed Potato?

A seed potato is a tuber that you bury in the soil in the hopes of growing a new plant. A seed potato will eventually grow into a new plant that is identical to the parent plant (the one the seed potato came from).

sprouted potato — A seed potato is a tuber that you plant to grow more potatoes.

Seed potatoes are bred for the purpose of growing new potato plants (rather than for eating). Sometimes, you might want to wait to plant a seed potato until after it has started to sprout (called chitting – more about this later).

Remember that seed potatoes are not the same thing as potato seeds – even though the names sound similar.

Sometimes, potato plants that are mature enough will flower. With proper pollination, these flowers will produce fruit.

purple potato flower — Potato flowers are white or purple, and with proper pollination, they can produce fruit.

Potato fruit grows above ground, and it looks a lot like green cherry tomatoes (potatoes and tomatoes are related: both are in the nightshade family).

However, the fruit is hard and poisonous, containing the toxin solanine (along with lots of potato seeds). In general, you will not want to grow potatoes from potato seeds taken from the fruit.

If you plant a potato seed, you will get a plant that is different from the one you took the seeds from. Planting tubers (seed potatoes) is how we get a new plant that is identical to the parent plant.

harvested potato fruit — Potato fruit (shown here) grow above ground, and they contain potato seeds, which are not the same as seed potatoes.
Image courtesy of user: MidgleyDJ via: Wikimedia Commons: https://commons.wikimedia.org/wiki/File:Potato_fruits.jpg

To summarize: potato seeds come from fruit that grows above ground. Seed potatoes are tubers grown underground and set aside for growing new plants.

The table below shows the differences between seed potatoes and potato seeds.

Seed Potatoes	Potato Seeds
Tuber	Fruit
Grows below ground	Grows above ground
Produces a new plant identical to parent plant	Produces a new plant that has different traits

What Do Seed Potatoes Look Like?

Seed potatoes look just like ordinary potatoes – after all, they are just tubers that we set aside for growing new plants. You might not be able to tell the difference between seed potatoes and store bought potatoes just by looking at them.

russet potatoes — Seed potatoes look just like regular potatoes. However, they are grown for a different purpose.

Remember that seed potatoes are sometimes covered with sulfur powder, which prevents rotting. However, this sulfur powder does not prevent the seed potato from sprouting and growing after you plant it.

What Is The Difference Between A Seed Potato & A Regular Potato?

Seed potatoes (from seed catalogs or gardening centers) are set aside for growing new plants, while regular potatoes (from grocery stores) are intended for eating.

Seed potatoes are not grown and treated the same way as grocery store potatoes. This is important because potatoes bound for grocery store shelves are often treated with sprout inhibitors.

potatoes clean for storage — Potatoes at the grocery stores are often treated with sprout inhibitors, which prolong shelf life but prevent optimal growth when planted.

These sprout inhibitors are great for grocery stores, since they increase shelf life (which reduces food waste). However, these same sprout inhibitors also prevent potatoes from sprouting after you plant them.

Seed potatoes are different from regular potatoes in another way: they are certified disease-free.

Is It Worth Buying Seed Potatoes?

Certified seed potatoes are grown carefully, and they undergo a rigorous inspection process to make sure they are disease-free. This means they will not bring the dreaded late blight (or any other potato diseases) to your garden.

late blight potato leaf — Planting certified seed potatoes prevents late blight and other diseases.

Also, seed potatoes are not treated sprout-inhibiting chemicals (like clorproham). This means the seed potatoes will sprout easily and grow without trouble after you plant them.

If you use store-bought potatoes to plant, wait until 1-inch sprouts grow to ensure viability before planting. Also, inspect the tubers for any signs of disease, and get rid of any that look suspect (don’t compost them, or the disease could spread to your garden later).

In my experience, plants grown from seed potatoes are bigger and more vigorous than plants from store-bought potatoes (I think this is because of the sprout inhibitors the grocery store ones have on them).

Where To Buy Seed Potatoes

There are lots of places to buy seed potatoes. You can go in person to a garden supply center to see if they have any.

Purple Peruvian potato — You can find seed potatoes in many different colors, including purple, red, yellow, and more.
Image courtesy of user Stephen Lea via Wikimedia Commons: https://commons.wikimedia.org/wiki/File:PurplePeruvianPotatoes.jpg

You can also buy seed potatoes from a print catalog or online from several different companies, including:

What Is The Best Way To Store Seed Potatoes?

The best way to store whole seed potatoes is at a temperature of 38 degrees Fahrenheit (3 degrees Celsius). Then, warm them up to room temperature the last two weeks before you plant them.

However, it is a little different for cut seed potato pieces. You should give them a little time to heal before planting.

Atlantic Potato — If you cut a seed potato into two or more pieces, give it time to heal (scab over) before planting it.

If left alone for 6 to 10 days, cut seed potato pieces will heal by forming a protective layer over cut areas. This protective layer will prevent disease after planting.

The University of Maine Extension suggests storing cut potato seeds at 50 to 55 degrees Fahrenheit (10 to 13 degrees Celsius) and at or above 90% humidity to encourage healing of cut areas.

After that, you can store at cool temperatures (38 degrees Fahrenheit) until two weeks before planting, as described above.

Another option is to wait until the seed potato pieces have sprouted before you plant them (more detail about this below).

The Complete Guide To Growing Potatoes

A complete reference and an ultimate guide that teaches you everything you need to know about potato selection, planting, care, harvest, and storage.

Buy Now

Learn More

What Is Chitting Seed Potatoes?

Chitting seed potatoes means to encourage sprouting before you plant them. This is sort of like a seed viability test – it helps to make sure that the seed potatoes are vigorous and able to grow after you plant them.

The Utah State University Extension suggests laying out seed potatoes with eyes up about 6 weeks prior to planting. Don’t stack them up – lay them out separately from one another.

The seed potatoes should be in medium light (but not direct sunlight) at a temperature of 70 degrees Fahrenheit (21 degrees Celsius). The sprouts (which grow from the eyes) should be around 1 inch long at planting time.

When To Plant Seed Potatoes

A good rule is to wait to plant potatoes until two weeks after the last spring frost date in your area. You can use this resource from the Old Farmer’s Almanac to find frost dates by zip code or city and state.

frosted leaf — Plant potatoes two weeks after the last spring frost date in your area.

For example, the last frost date in Boston, MA is April 8. Counting ahead 2 weeks (14 days), we get a potato planting date of April 22 (8 + 14 = 22).

However, the calendar isn’t the only thing to pay attention to. The soil itself is also important.

The soil should be moist, but not soggy. Wet soil means potatoes will rot before they can grow.

Also, the ground should be soft enough to dig easily. That means you should wait until after the soil thaws out.

shovel — Wait until the ground has thawed to plant potatoes. That way, you can dig easily.

Remember that potatoes will not grow until the soil temperature is at least 45 to 50 degrees Fahrenheit (7 to 10 degrees Celsius).

In addition, if you plant too early, the seed potatoes have a higher chance of rotting in cool, damp soil. There is also an increased chance that an unseasonably late hard frost in spring will kill back growth to the soil surface.

On the other hand, you don’t want to wait too long to plant seed potatoes in hot climates. Tuber formation stops at a soil temperature of 80 degrees Fahrenheit (27 degrees Celsius).

Can You Cut A Seed Potato?

You can cut a seed potato into smaller pieces to increase the number of plants you get (aim for at least one eye per piece). However, don’t overdo it: it is possible to make seed pieces too small.

Small seed pieces might not have enough energy to grow into healthy plants, especially if you bury them too deep. Small seed pieces might also result in smaller, less vigorous plants.

cut potato with eyes — When you cut a seed potato, make sure there is at least one eye per piece.

Here are some guidelines for cutting seed potatoes:

Aim for a weight of around 2 ounces per piece (give or take) – so a pound of seed potatoes (16 ounces) should give you 8 pieces, or 8 plants.
Aim for at least once eye per piece (two is better) – a seed potato piece without any eyes is “blind”, and in that case, there are no buds to sprout and grow.
Use a clean knife to cut pieces – wipe your blade with alcohol before cutting to make sure it is clean. Even if you are using certified seed potatoes, you don’t want to introduce disease from a dirty cutting tool.
Allow time for cut pieces to heal – a protective layer will form over cut surfaces (scabbing – not the same as the potato disease called scab!) This prevents disease after planting.

Does The Size Of A Seed Potato Matter?

The size of a seed potato does matter. With larger pieces, you will probably get plants that emerge sooner and produce higher yields, but there is a point of diminishing returns.

rows of potato plants — Potato plants from larger seed pieces will emerge sooner and produce higher yields, but don’t cut your seed pieces too big.

Tiny pieces or ones without eyes are not viable. The University of Maine Extension suggests that you avoid cutting seed potato pieces that are too old. Instead, you should only cut seed potatoes at an earlier stage (you can learn more about the stages here).

Will Seed Potatoes Freeze In The Ground?

Seed potatoes can freeze in the ground if you plant too early, or if a hard freeze comes along when you planted at a shallow depth.

Generally though, seed potatoes in the ground will be protected from freezing. The soil will insulate the seed potatoes, preventing them from getting too cold.

If the seed potato has sprouted and emerged above ground, that is a different story. The part of the plant above ground will die back in a hard freeze – but the plant can make another attempt at growth, using the energy and roots underground to make a comeback.

Will Seed Potatoes Rot In The Ground?

Seed potatoes can rot in the ground, just like any other potatoes. However, if you plant at the right time (when the soil is not too cool and damp from winter), there is less chance of rot.

To avoid rot in seed potatoes:

Wait until the soil dries a bit (damp soil is more likely to cause rot)
Give cut seed potato pieces time to heal before planting (see suggestions above)
Don’t plant seed potato pieces too deep (a depth of 4 inches or so is a good rule)

Can You Eat Seed Potatoes?

You can eat seed potatoes – they come from basically the same place as other types of potatoes (they are all tubers from a potato plant!) However, seed potatoes are bred specifically for planting to grow more potatoes.

It wouldn’t make sense to eat them, since they are certified disease-free and grown specifically to avoid the spread of common diseases in home gardens and in large-scale agriculture.