Are Potatoes Perennial? (3 Facts About Potatoes & Harvesting)


Potato plants produce nutritious tubers that are useful in lots of dishes.  But will the plant survive year after year in the garden?

So, are potatoes perennial?  Potatoes are perennial and can survive for years in warm climates.  If cold kills the top part of the plant, tubers can send up new growth in the spring.  Potatoes are treated as annuals and the tubers are harvested each year – especially in cold climates.

Of course, if you leave some of the potato tubers underground (by accident or on purpose), you can sometimes get new plants without even trying!

In this article, we’ll take a closer look at potatoes and how they grow.  We’ll also answer some common questions about growing potatoes.

Let’s get going.

Are Potatoes Perennial?

Potatoes are perennial, so in theory the plants can survive for years on end.  However, this assumes the proper climate.

potato plants in container
Potato plants are perennial and can survive for years under the proper conditions.

Although potatoes are a cool weather crop, a hard frost or freeze can kill the plant’s growth above ground.  However, this doesn’t necessarily mean the end for the potato plant:

  • If a spring frost kills the potato plant above ground, the underground part can still send up new shoots and continue growing.
  • If a fall frost kills the potato plant above ground, the underground tubers can lay dormant until spring and start sprouting to form a new plant when the soil warms up.

 In gardening, potatoes are treated as annuals, and their tubers are harvested in the summer or fall after growth has stopped.  The life cycle of a potato treated as an annual is as follows:

  • Potato tuber forms eyes – as potato tubers mature, they form “eyes”.  Potato eyes are small indents that contain buds which can sprout into new growth.
  • Potato tuber eyes begin to sprout – after a period of dormancy (that is, actual or simulated winter cold), some of the eyes on potato tubers will begin to sprout.  This is more likely to happen in warm, humid, well-lit areas.
  • Sprouted potato tubers are planted – after the eyes sprout, potato tubers are planted, either as a whole sprouted potato or as cut pieces with at least one sprouted eye per piece.  (You can learn more about how to plant sprouted potatoes in my article here).
  • Potato plants emerge from the soil – the sprouts grow up towards the soil surface and break through.  They then use sunlight to produce energy by photosynthesis.
  • Hilling & growth – as potato plants grow taller, use “hilling” to pile up soil around the base of the plant.  This insulates the plant from soil temperature changes and protects tubers from sunlight exposure (which causes green & toxic potatoes).
  • Potato plant forms flowers – this may not always happen, but if it does, don’t worry!  This is a totally natural part of a potato plant’s life cycle.  It can also help to indicate when the underground tubers are ready for harvest.  If the flowers are pollinated by bees or other creatures, they may form fruit.
  • Potato plant produces fruit (above ground) – this may not always happen, but it is also a normal part of a potato plant’s life cycle.  Potato plant fruit forms above ground and is green, with the appearance of tomatoes (potatoes and tomatoes are related members of the nightshade family).  These green fruits contain toxic solanine, but they also contain seeds.
  • Potato plant falls over – this may happen well before a frost kills the potato plant in fall.  The shoots above ground may turn yellow, but this is often a sign that the plant is done growing and the tubers have fully formed – it is time to harvest them!
  • Potato storage & sprouting – potatoes can store for weeks to months, depending on how they are prepared & treated and the storage conditions (temperature, humidity, and light).  Potatoes will eventually sprout, and their life cycle starts all over again when you plant them.
sprouted potato
You can plant a sprouted potato in spring to get a new potato plant, which will produce more tubers.

Can You Leave Potatoes In The Ground Over Winter?

You can leave potatoes in the ground over winter.  Some gardeners do this on purpose to allow “volunteer” potato plants to emerge.

Baby Potato Plant
Volunteer plants may emerge in spring from buried potato tubers.

Other gardeners simply forget to harvest a small area of potatoes, or they miss some tubers during harvest.  Either way, potato tubers left in the ground over winter can grow into new plants.

However, before potato tubers can turn into new plants, they must go through a period of dormancy.  Dormancy simply means a period when growth and development slows down or stops.

Plants use dormancy to prepare for cold weather, freezing temperatures, and a lack of water or nutrients.  Dormancy also protects plants by preventing them from growing under adverse conditions.

russet potatoes
Potato tubers undergo a dormancy period before they begin to sprout.

For example, winter dormancy prevents potato plants from growing during a time when frost is likely to kill them (otherwise, they would waste too much energy and would struggle to survive).

According to the University of Maine, the length of dormancy of potato tubers depends on the variety.  They suggest that cutting potato tubers will advance the age of the tubers (aim for at least one sprouted eye per cut piece of seed potato).

Sprouted potato tubers or pieces will remain dormant if planted in soil that is too cold, too wet, or too dry.  The best soil temperature for planting potatoes is 45 to 50 degrees Fahrenheit (7 to 10 degrees Celsius).

If the soil is too cold, too dry, or too wet, potato tubers will remain dormant (or even worse, they may rot before growing).  The University of Florida suggests that potato sprouts will emerge from the soil 10 to 14 days after planting.

What Happens If You Don’t Harvest Potatoes?

If you don’t harvest your potatoes at all, they may sprout and grow into new plants the following spring (after winter dormancy).  However, there are some dangers to potato tubers left underground for the fall and winter, including:

  • Frost – this is more likely to affect tubers that are buried at a shallow depth in cold climates.  However, it is still a possibility that freeze could damage the tubers and prevent new growth in the spring.
  • Pests – both animal and insect pests have a larger window to feed on potato tubers when you leave them in the ground
  • Rot – potatoes that stay in wet soil for too long are prone to rot, which will also prevent new growth when spring comes.
potato late blight
Cold, wet soil can cause potatoes to rot or subject them to diseases (this one has blight).

Your best bet is to harvest your potato tubers, store them in a cool, dry, dark place, and then sprout them and plant them in the spring after they break dormancy.

Can You Eat Potatoes That Have Not Flowered?

You can eat potato tubers from a plant that has not flowered.  A flowering potato plant can help to indicate when the tubers are mature and ready for harvest.

purple potato flower
A flowering potato plant is on its way to producing tubers.

According to the Old Farmer’s Almanac, harvest potatoes according to the following:

  • For new potatoes (smaller, more tender potatoes with thin skins), harvest the tubers 2 to 3 weeks after the plant stops flowering.
  • For mature potatoes (larger potatoes with thicker skin), harvest your potatoes 2 to 3 weeks after the plant dies back.

Of course, potato plants don’t always flower before the growth above ground starts to turn yellow and die back.  Although the flowers are one sign that the potato plant is progressing, watch for the plant to die back (or dig up a sample tuber to check).

Do Potatoes Keep Growing After The Plant Dies?

Potatoes do not grow after the plant dies.  The green shoots (the part of the plant above ground) produces energy by photosynthesis and stores starches in the tuber.

potato vines fallen over
When potato plant vines start to turn yellow and fall over, the tubers are just about done growing.

Once the plant dies back, there is no more photosynthesis and no more storage of starch.  The tubers will not grow any more.

At that point, you can harvest them.  The University of Maryland Extension suggests leaving potato tubers underground for 2 weeks after the plants die back.

This will give them time to form thicker skins, which will improve storage.  Do not wash potatoes before storing – brush off dirt if you want, but only wash potatoes right before you prepare them for eating!

Conclusion

Now you know about potatoes and how they grow (they are perennial, but are treated as annuals in the garden).

I hope you found this article helpful.  If so, please share it with someone who can use the information.

If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here.  Enjoy!

~Jonathon

jonathon.david.madore

Hi, I'm Jon. Let's solve your gardening problems, spend more time growing, and get the best harvest every year!

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