If this is your first year planting potatoes, or if you got a late start on your garden, you might be wondering if the time for planting potatoes has passed. After all, you don’t want to put in the effort to plant a crop of potatoes that won’t grow well.
So, when is it too late to plant potatoes? Most gardeners should plant potatoes by the end of May for spring planting. This allows enough time for the plants to grow & mature before cool weather (and frost) in fall. Plant before soil temperatures reach 80 degrees Fahrenheit (27 degrees Celsius), since tubers will stop forming if it is too warm.
If you live in a very warm climate, you may be able to plant mid-season and late season potato varieties in July or even August to get a second harvest later in the year.
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.
If you live in a cold climate, you can extend the growing season with a greenhouse, row covers, or mulch to protect against frost at the end of the season.
In this article, we’ll take a look at the many factors that determine when you can plant potatoes, including frost dates or the type of potato and its time to maturity.
Let’s get started.
When Is It Too Late To Plant Potatoes?
To determine when it is too late to plant potatoes, there are 3 main factors to consider:
- 1. Variety of Potato (determines the number of days from planting to maturity)
- 2. First Frost Date (cold temperatures in the fall will kill potato plants)
- 3. Desired Harvest (new potatoes, mature potatoes, large potatoes)
Let’s start by looking at the different types of potatoes you can choose to grow.
Variety
The variety of potato plays a big part in when to plant your crop. The variety you choose determines the time to maturity for your potato plants.
The time to maturity (or days to maturity) is the number of days it takes for a potato plant to grow into a mature plant and produce tubers that you can harvest.
- Early Season – these potatoes mature quickly, taking as little as 60 to 80 days (8.5 to 11.5 weeks) to produce tubers. For example, the Red Norland potato from Gurney’s takes 70 days to mature.
- Mid-Season – these potatoes take a little longer to mature, taking 80 to 90 days (11.5 to 13 weeks) to produce tubers. For example, the Red Pontiac potato from Burpee takes 80 days to mature.
- Late Season – these potatoes need the most time to mature, taking over 90 days (13 weeks) to produce tubers. For example, the Princess Laratte potato from Burpee takes 90 to 110 days to mature.
You can see an infographic and some selected varieties of early, mid, and late season potatoes here.
You can learn about early potatoes (and some selected varieties) here.
Avoid planting potatoes when the ground is still wet from heavy spring rains. Otherwise, they will rot before they can sprout and grow!
Planting too early in the spring also exposes your potato plants to frost, which can kill them or set them back (more on this later).
You can plant some potato varieties as late as July 1st – as long as you live in a mild climate. If you want to store your potatoes over the winter, late season potatoes are the best option (since harvest comes closer to winter).
Frost Dates
The first frost date in the fall will tell you if it is too late to plant potatoes. There is a 30% chance that no frost will occur before the first frost date (or first fall frost date).
For example, in Boston, MA, the first fall frost date is November 3. This means that there is a 30% chance of getting at least one frost on or before November 3. In other words, there is a 70% chance that no frost will occur before November 3.
First frost dates will vary widely depending on where you live. For example, the first frost date in Montpelier, Vermont is September 24, while the first frost date in Atlanta, Georgia is November 13. In Miami, Florida, frost is very rare, and may not occur for years on end.
Before you decide whether it is too late to plant potatoes, use this tool from the Old Farmer’s Almanac to find the last fall frost date in your area.
Desired Harvest
Depending on the size of potatoes you want at harvest, you might be able to get away with planting a little bit later in the year.
New Potatoes
If you want new potatoes (small, less mature potatoes with thin skins), you can harvest 2 to 3 weeks after the plant stops flowering. Not all potato plants will flower, so you may need to dig in the ground every once in a while to see how they are growing.
Mature Potatoes
Mature, full-size potatoes have thicker skins, and they take longer to grow than new potatoes. Basically, you let new potatoes grow for a bit longer so they can mature fully and get bigger.
Mature potatoes will be ready for harvest 2 to 3 weeks after the foliage on the plant dies back. If you plant late in the season, there will be less time for the potatoes to grow. As a result, you will get smaller potatoes on each plant and fewer potatoes in total.
Summer heat with soil temperatures over 80 degrees Fahrenheit (27 degrees Celsius) will stop tubers from forming. On the other hand, fall frosts will kill the plant and stop growth.
Can You Still Plant Potatoes In July?
You might be able to plant potatoes in July if you live in a warm climate and you choose potato varieties that don’t take too long to mature.
For example, if you live in Boston, Massachusetts, your first frost date is November 3. Let’s say you choose a potato variety that will be ready in 100 days (a little over 14 weeks) after planting.
Working backwards, you could plant in July and still get potatoes by November 3 (5 days in July + 31 days in August + 30 days in September + 31 days in October + the first 3 days in November = 100 days).
| Month | Days |
|---|---|
| July | 5 |
| August | 31 |
| September | 30 |
| October | 31 |
| November | 3 |
| Total | 100 |
Just remember that potato tubers stop forming if the soil gets too hot.
Can You Still Plant Potatoes In August?
You might be able to plant potatoes in August if you live in a very warm climate and you choose fast-maturing potato varieties.
For example, if you live in Atlanta, Georgia, your first frost date is November 13. If you choose Red Norland potatoes (an early season variety), they will be ready for harvest about 70 days (10 weeks) after planting.
That means you could plant in August and still get potatoes by November 13 (30 days in September + 31 days in October + the first 13 days in November = 74 days).
| Month | Days |
|---|---|
| September | 30 |
| October | 31 |
| November | 13 |
| Total | 74 |
Can You Plant Potatoes In The Fall For Next Year?
If you plant potatoes in fall (or leave them underground without harvesting them), they will sprout and grow into new plants the following spring. However, the longer potatoes stay underground, the more chance they will rot or pests (animal or insect) will eat them.
Your best bet is to harvest and store your potatoes and wait to plant sprouted potatoes in the following spring.
Can Potatoes Grow In Winter?
Potatoes can grow in winter in very warm climates. However, a frost will kill the foliage back to the ground. The plant will regrow, so you don’t need to plant new seed potatoes.
Your best bet is to grow potatoes by planting in spring (or early to mid summer for a 2nd later harvest in warmer climates).
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.
When To Start Your Potato Plants
You can use the factors mentioned above to figure out when it might be too late to plant your potatoes. For example, let’s assume that:
- you live in Boston, MA
- you want to plant a late-season potato variety, such as Princess Laratte
- you want to harvest mature potatoes (not new potatoes)
We know that the last frost date in Boston is April 10. We also know that Princess Laratte potatoes take 90 to 110 days to mature.
Let’s say that we are planting a week late to reduce the chance that a late spring frost will kill our potato plants when they emerge. So, we wait until April 17 to plant our potatoes.
Working forwards from April 17, we can see that the potatoes would be mature on July 16 at the earliest (13 days in April + 31 days in May + 30 days in June + the first 16 days in July, for a total of 90 days).
| Month | Days |
|---|---|
| April | 13 |
| May | 31 |
| June | 30 |
| July | 16 |
| Total | 90 |
For spring planting, you can plant potatoes as soon as ground can be worked (that is, when it thaws out). However, remember that potatoes will not grow until the ground is at least 45 to 50 degrees Fahrenheit (7 to 10 degrees Celsius).
When planting potatoes, the soil should be moist, but not wet. Wet soil causes potatoes to rot before they can grow.
According to the Old Farmer’s Almanac, you can take a chance and plant potatoes 6 to 8 weeks before the last spring frost date in northern regions. These crops mature earlier in the season, but there is more risk of a late spring frost damaging or killing the plants when they emerge.
Especially in cold northern regions, it is safer to plant your potatoes two weeks after the last frost date.
(You can learn how to plant sprouted potatoes in my article here).
How To Protect Potato Plants From Cold
Potato plants are a cool weather crop, so they can tolerate some cool temperatures. However, a hard frost can kill back any growth to the ground, so it pays to protect them if possible.
In case of a late spring frost or early fall frost, here are a couple of ways you can protect your potato plants from cold.
Greenhouse
The soil in a greenhouse will get warm enough for planting potatoes much sooner than the soil outside. You also have more control over the soil moisture inside your greenhouse.
You can even choose to plant potatoes in containers inside your greenhouse if you wish (you can also try planting potatoes in a straw bale!) For more information on growing potatoes in straw bales, you can read my article here.
If you plant your potatoes a little late, you can use a greenhouse to extend the growing season and protect your potato plants from fall frosts.
Row Covers
You also have the option of using row covers to protect potato plants against late spring or early fall frosts. Row covers are made from fabric, and they protect plants from cold (and insects), while also allowing sunlight to get through.
One brand of row cover with varying levels of protection is Agribon. For example, Agribon AG-50 offers 6 degrees of frost protection (down to 26 degrees Fahrenheit).
You can learn more about row covers in my article here.
Mulch
Mulch is another great way to keep potato plants a little warmer. Even if a frost comes, a layer of mulch hilled up around a potato plant will protect part of the plant.
Even better, hilling during the growing season is encouraged for potato plants, and it won’t hurt them. You can learn more about hilling potatoes (and why to do it) in my article here.
You can use lots of materials for mulching and hilling around your potato plants. Some common ones include:
- Straw
- Grass clippings
- Leaves
- Compost
All of these materials will eventually decompose, adding both nutrients and organic matter to your garden.
What Happens If You Plant Potatoes Too Late?
If you plant your potatoes too late, you will have problems with heat in the summer or with cold in the fall.
Summer Heat
The first problem you may face with a spring planting of potatoes is the summer heat. Potato plants are a cool weather crop, and they will stop producing tubers if the soil is too warm.
Higher temperatures and brighter sunlight also cause soil to dry out faster. Remember that young potato plants are not yet established with strong roots.
That means you will need to work harder to give them enough water. This can be a big chore in a large garden, especially without drip irrigation or a sprinkler system for watering.
Fall Frost
Even if you manage to deal with the summer heat by planting later in the season, you still need to worry about frost in the fall.
A hard frost will kill potato plants, and an early fall frost will stop the plants from growing larger tubers. If the ground freezes, it will be difficult to harvest your potatoes without damaging them (if you can get them at all!)
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.
Conclusion
Now you have a better idea of when it is getting too late to plant potatoes – and when you might be able to plant for a later harvest. You also know a little more about how to protect your potato plants from frost, if necessary.
If you are in a warm climate or you have space indoors, you can learn more about growing potatoes in winter in my article here.
I hope you found this article helpful – if so, please share it with someone who will find the information useful.
You can learn about the time to maturity for various types of potatoes here.
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~Jonathon