These spunky spuds are staples in many dishes, but they can sprout at times for no apparent reason. Why do potatoes sprout in the first place?
Potatoes sprout in order to produce new plants. This happens because enzymes in the potato convert its starch to sugar, signaling the production of sprouts from the eyes or buds of the potato.
Just know that most potatoes, especially those sold in grocery stores and supermarkets, are treated with growth or sprout inhibitors. Some treatments cause delays while others prevent the potato from growing altogether.
Factors Contributing to Potatoes Sprouting
Potatoes can be stored for a long time but they will begin to sprout eventually. There are 5 main factors that make potatoes sprout: temperature, humidity, variety, light, and dormancy break.
Once we understand these factors, we can take the proper steps to slow down the process and increase the overall potato storage time.
Temperature
Temperature Range | Description |
Below 32°F (Below 0°C) | Tubers can get damaged. |
38° to 40°F (3.33° to 4.44°C) | For long-term storage, prevents sprouting. |
40° to 50°F (4.44° to 10°C) | Delays sprouting. |
51° to 69°F (10.56° to 20.56°C) | Encourages moderate sprouting. |
70°F and above (21.11°C and above) | Encourages faster sprouting. |
Warmer conditions increase the likelihood of your potatoes sprouting. Increasing temperatures, similar to spring and summer, encourage them to start growing.
If you want to keep them for longer, store potatoes between 40° to 50° F (4.44 to 10°C) These temperature ranges slow down potato metabolism, reducing the chances of sprouting.
Warmer environments, like room temperatures or above 70° F (21.11°C), speed up sprouting. This works if you’re interested in growing excess potatoes.
Humidity
When humidity is high, it creates the perfect environment that promotes potato sprouting. This is because moisture triggers the enzymes responsible for sprout growth in potatoes.
To prevent sprouting, store potatoes in a dry location with good ventilation. Make sure they are not in contact with damp surfaces.
Keeping a 90 to 95% humidity is recommended to prolong sprouting for up to 8 months.
Also, avoid washing potatoes before storage. Moisture from washing them can encourage them to sprout.
Potato Variety
Potato varieties vary in their sprouting tendencies. Some sprout more than others, especially those with thin skins and high sugar content.
Russet potatoes, famous for their thick skins, don’t sprout easily. On the other hand, red or fingerling potatoes tend to sprout more easily.
Light
Potatoes, like most plants, are sensitive to light. It doesn’t matter if the source is natural or artificial.
Once potatoes sense light, they start the process of producing sprouts. It begins with the potato skin turning green, which is a sign that the potato is starting to sprout and may contain higher levels of solanine.
Solanine is a toxic compound. While eating small amounts of potatoes that have turned green is not harmful, it’s a diet that is highly discouraged.
Potatoes don’t need soil and don’t even need to be buried right away in order to sprout. You can even put them on top of the soil and they’ll still sprout!
In fact, there’s a gardening technique called hilling. Hilling potatoes involves piling soil or mulch around the base of potato plants as they grow, which helps protect the developing tubers from extreme light exposure yet encourages increased yield.
Dormancy
Potatoes go through dormancy as part of their natural built-in mechanism that keeps them from sprouting right after harvest. There is no set period as some potatoes tend to break their dormancy faster than others.
However, if potatoes are exposed to light, warm temperatures, and high humidity, the dormant period gets shorter.
Tips to Delay Potatoes from Sprouting
There are times when you want to keep your potatoes from sprouting. Whether you’re planning to store them for later consumption or it’s not yet time for planting, there are techniques to keep them from sprouting earlier than expected.
Ideal Temperature
The most ideal temperatures to keep your potatoes from sprouting range from 38° to 50°F (3.33° to 10°C). Most homeowners would agree that 38°F (3.33°C) is the most optimal.
Proper Humidity Levels
Keep potatoes at 90 to 95% relative humidity to keep them from drying out. Coupled with the recommended temperatures of 38° to 50°F (3.33° to 10°C), this condition will keep your potatoes from premature sprouting.
Too low and they may dry out. Too high and your potatoes may sprout or even experience fungal issues.
Pick the Right Variety
Pick potatoes that have known longer dormancy periods. Russet Burbank, Classic Russet, Umatilla Russet, and Alpine Russet come to mind.
Just remember that you’re trying to delay sprouting, not preventing them from sprouting at all. Most potatoes tend to sprout anywhere from 30 to 140 days after harvest, depending on the variety.
Keep Away from Light
Keep your potatoes in the dark. While light can encourage sprouting, potatoes don’t rely on it as the only factor to begin sprouting.
Once other factors come in, your potatoes can begin to sprout even when kept in the dark.
Good Ventilation
Keep the air moving to regulate temperature and humidity. Baskets, mesh bags, and wooden crates are great storage pieces to encourage good airflow.
Ventilation prevents air from becoming stale and stagnant, preventing fungal issues.
Ethylene Gas Absorbers
Some fruits and vegetables produce ethylene gas, which can cause potatoes to sprout faster. To avoid sprouting, potatoes are exposed to ethylene gas absorbers or inhibitors.
Place these products near your potatoes. The nearer they are to your spuds, the better they keep ethylene gas away from your precious potatoes.
Ethylene scavengers like silica gel, activated carbon, zeolite, and bentonite can absorb ethylene due to their porous nature. However, they cannot oxidize ethylene by themselves.
Be mindful of where you store your potatoes too. Avoid placing them near apples, avocados, tomatoes, or other ethylene-producing produce.
Do Regular Inspections
Check your potatoes frequently for any signs of sprouting, softening, drying, decay, and other potato issues. Immediately remove these to prevent the issues from spreading and affecting the remaining healthy batches of potatoes.
Don’t Wash before Storage
Washing introduces moisture to potatoes, encouraging them to sprout. To keep them from sprouting, wash potatoes only just before using them.
Tips to Accelerate Potato Sprouting for Planting
Now if you want to go the opposite route of preventing potatoes from sprouting, we got you. We’ve listed our best practices to encourage potatoes for sprouting and planting.
Maintain Optimal Temperature
Based on the table we’ve shown before, anything above 50°F (10°C) encourages potatoes to start sprouting. If you can get 70°F (21.11°C), that’s the ideal spot.
Ensure High Humidity
Keep your potatoes firm and plump at 90 to 95% in relative humidity. At this condition, they won’t dry out nor will they develop issues from overly humid levels.
Chitting for Better Results
Chitting involves encouraging seed potatoes to sprout indoors before being planted. The process involves placing the seed potatoes in a cool well-ventilated spot with the sprouting side facing up.
Once sprouts are visibly 1 to 2 inches long, they can be planted in-ground or in containers. This is optional but it jumpstarts growth, allows better spacing, and leads to higher harvest yields.
Consider Green Sprouting
Also known as pipping, green sprouting involves planting potatoes that have turned green. Since you won’t be eating them anyway due to the solanine content, you can plant them instead.
Avoid Commercially-Treated Potatoes
Store-bought potatoes typically contain a sprout inhibitor called clorproham. This chemical prevents sprouting during storage, transport, and display in grocery stores.
While it benefits stores and consumers, it won’t end up with sprouting potatoes for planting. Washing may help, but overly wet potatoes might rot instead of sprout.
Get Certified Seed Potatoes
Use certified seed potatoes specifically grown for planting to kickstart the potato-sprouting phase. These have not been treated with sprout inhibitors and are readily available from reputable seed companies during the appropriate season.
What To Do With Sprouted Potatoes
Some homeowners subscribe to the idea of eating potatoes that have sprouted, but we don’t really recommend it as it does have toxic compounds at this stage. Don’t worry, your sprouted potatoes are still pretty useful!
In fact, there are two ways to deal with sprouted potatoes. You can either plant the whole sprouted potato or cut the potato into pieces.
Planting the Whole Sprouted Potato
This method offers some perks. You won’t need to wait for cut potato pieces to “cure” before planting.
Plus, your sprouts will have more energy to kickstart their growth early in the season, often leading to larger and more robust plants.
Simply plant the potatoes as you normally would. Provide the right plant care and your potatoes should be fine and ready when harvest time comes!
Cut the Potato into Pieces
This approach allows you to maximize your potato yield. Just make sure that each piece has at least one sprouted eye after you’re done cutting.
Don’t make the pieces too small as they may lack the necessary energy to break through the soil’s surface and begin growing.
If a potato plant grows from a piece that’s too small, it’ll end up weak because it won’t have sufficient energy from starches and sugars to give it a strong start in life.
When you plant that sprouted potato, you’ll soon see a fresh new plant emerging from the soil.