When frost threatens, it is natural to worry about the plants in your garden – but should you worry about potato plants? Potatoes are a cool weather crop, but that doesn’t mean they are invincible.
So, can potato plants survive frost? Potato plants can survive a light frost (temperatures of 28 to 32 degrees Fahrenheit). Potato plants may be able to survive a hard frost (temperatures below 28 degrees Fahrenheit). In some cases, a frost may damage potato plant leaves and stems, but new shoots can emerge and continue growing.
Of course, there are ways to protect your potato plants from cold, whether they are young or established.
In this article, we’ll talk about the signs of frost damage in potato plants and ways you can protect potato plants from frost.
Can Potato Plants Survive Frost?
A potato plant can survive light frost in spring. According to the Michigan State University Extension, a light frost means temperatures of 28 to 32 degrees Fahrenheit (-2 to 0 degrees Celsius).
In some cases, potato plants can survive a hard frost. A hard frost means temperatures less than 28 degrees Fahrenheit (-2 degrees Celsius).
It is important to remember that freezing refers to temperature, and frost refers to visible frost on the ground or plants. It is possible to get freezing temperatures without visible frost, or a frost without freezing temperatures.
Potatoes are a cool season crop, but that doesn’t mean they like it cold all the time. According to the Old Farmer’s Almanac, some gardeners plant potatoes 6 to 8 weeks before the last frost date.
However, temperatures below 28 degrees Fahrenheit could kill the part of the plant above the soil. At that point, the plant would need to start from scratch by sending up new growth, costing time and energy.
The Old Farmer’s Almanac suggests that the soil temperature should be at least 50 degrees Fahrenheit (10 degrees Celsius) before planting potatoes. Ideally, plant potatoes in the 2 weeks leading up to the last spring frost date in your area.
This gives a shorter growing season, but reduces the chance of frost damage to your potato plants. You can use this tool from the Old Farmer’s Almanac to find the last spring frost date in your area.
Later in the season, potato plants will grow better with warmer temperatures. According to the University of Illinois Extension, potato tubers form best at soil temperatures of 60 to 70 degrees Fahrenheit (16 to 21 degrees Celsius).
Although potatoes can tolerate some frost, they may suffer frost damage at colder temperatures.
What Does Frost Damage Look Like On Potato Plants?
According to the Iowa State University Extension, minor cold damage on potato plants will result in black edges (margins) on the leaves. In more severe cases, all of the plant that is above ground (shoots and leaves) will succumb to extreme cold.
The extent of the damage will depend on:
- Cold Severity (how far below freezing is the air temperature?)
- Length of Exposure (how long was the plant exposed to the cold?)
- Frost Protection (how much protection did the plant have against the cold?)
Do Potato Plants Recover From Frost Damage?
In some cases, a potato plant can recover from frost damage. In cases of minor frost damage, the plant’s shoots will continue growing and producing new growth.
In a case of major frost damage, the leaves and shoots above ground may not recover. However, according to the Iowa State University Extension, the potato plant will send up new shoots in 10 to 14 days.
As long as the plant has enough stored energy, it should be able to regrow and eventually produce tubers. However, it might take longer to get a harvest later in the season, and the harvest might be reduced.
Can Potatoes Stay In The Ground After Frost?
Potatoes can stay in the ground after frost. If the potato plant above ground survives the frost, then it can continue to grow the tubers.
If the potato plant does not survive frost, the tubers will still be safe underground – they just won’t grow any more. You can harvest the tubers at any point after the plant dies back.
Just be sure not to wait too long to harvest the tubers. If the ground freezes, it will be almost impossible to dig your potatoes.
After digging up your potatoes, be sure to cover them from sunlight. Otherwise, they will turn green and may produce solanine (a toxic substance).
Bring your potato tubers indoors to brush the dirt off and cure them before storage.
How To Protect Potato Plants From Frost
It is true that potato plants can survive frost. However, Mother Nature will sometimes surprise you with a rapid dip in temperatures (colder than the weather forecast called for!)
In those cases, it makes sense to protect your potato plants from cold. Not only will this prevent damage to the leaves and shoots above ground, but it will give the tubers more time to develop.
There are 3 methods that you can use to protect potato plants from frost:
- Cloche – this is good for younger plants that have just emerged.
- Row Cover – this is good for larger, more established plants, or for an entire row of plants.
- Greenhouse – this requires the most work to setup, but it can keep your plants quite a bit warmer than the outside air.
A cloche is a clear cover made of plastic or glass. In a garden, it is used to protect plants from cold, wind, and pests.
A cloche acts as a sort of “mini greenhouse” that traps heat from sunlight. This warms the air and soil underneath the cloche.
A cloche often has a vent on top to let in fresh air and prevent it from overheating. Most cloches are meant for a single young plant.
However, you can also find “row cloches” that cover multiple plants. Another option is to use wire cloches.
These will not protect plants from cold, but you can wrap a frost blanket or row cover over them to provide frost protection.
Row Cover (Frost Cover)
A row cover is a sheet of lightweight fabric that protects plants from cold, wind, and pests. A row cover is often made of polyethylene, polyester, or polypropylene.
Row covers vary in thickness, which determines the amount of light that gets through. Thicker row covers are heavier, but allow less light through and offer more cold protection.
Depending on the thickness, a row cover can provide 2 to 10 degrees Fahrenheit (1 to 6 degrees Celsius) of cold protection. Heavyweight row covers are better for protecting plants from hard frost or intense sunlight.
Another advantage of row covers is that you can water through them, since they are water permeable.
Often, a series of half-hoops are used to support a row cover so that it doesn’t come in contact with the plants themselves.
A greenhouse is a structure with glass or plastic sides or roofing. It traps energy from sunlight and warms the air and soil inside the greenhouse.
Some greenhouses have vents to let in air if the temperature inside gets too hot. Otherwise, you will need to open the door slightly to allow air circulation.
A greenhouse is a good option if you want to keep potato plants warmer throughout the growing season. This will help you to avoid damage from both spring and fall frost.
In an area with a short growing season, a greenhouse could help you to get a much better harvest.
Now you know about how frost affects potato plants. You also know how to protect them from cold in the early stages and later in the season.
You might find it helpful to read my article on the best temperature for growing potatoes.
I hope you found this article helpful. If so, please share it with someone who can use the information.
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