How to Know When to Harvest Potatoes

Since potatoes are such a popular food that everyone knows and loves to eat, they’re one of the most commonly grown vegetables. They’re also quite easy to grow and store, all the more reason to grow potatoes, even for beginner gardeners and homesteaders.

But, of course, we don’t grow them for the plant- we grow them for the actual potatoes! So, it’s important to know everything about harvesting potatoes, from the technique to the time frame. This is why we wrote an entire article dedicated just to this topic, so that you have an in-depth guide to help you know when is the right time to harvest your potatoes.

Luckily, the signs that the potatoes are ready are quite clear and the process is pretty simple, so you’ll get the hang of it pretty quickly. Many gardeners just need a guide for their first harvest, then every year after they feel comfortable digging them up themselves.

Something that makes this process so easy is that there isn’t an exact time when you need to harvest, but rather the size of the potatoes changes depending on when you harvest. This is something really great about growing potatoes yourself: you can decide when to harvest and therefore what size potatoes you’ll have.

Potatoes also come in so many different varieties, so you can grow several different types of potatoes in your garden. Just amongst sweet potatoes, there’s over 20 different varieties! Plus, regardless of whether you’re growing golden, red, or sweet potatoes, they all have the same indicators and process for harvesting.

Time Frame for Harvesting

So, although it’s ultimately up to you to decide when you want to harvest the potatoes, there is a general time frame for when you’ll be digging. Potatoes take 3 months from seed to harvest to form and begin growing, and then from there you have a period of 1 to 2 months to harvest them.

You want to plant your potatoes in late spring or early summer, depending on the climate you live in. This means the potatoes will be ready for harvest in late summer and can be harvested up to September or October, depending on how cold the fall is for you.

There’s two main reasons for harvesting potatoes that will determine when you want to harvest: potatoes for eating soon and potatoes to store for the winter. These are called new potatoes and storage potatoes, respectively.

The distinguishing factor between new and storage potatoes is their size- they’re not at all different varieties of potatoes. By harvesting earlier, the potatoes will be smaller and softer, making them better to be eaten right away. The longer they stay in the ground, the more they ripen and harden, which means that they’ll storage better- plus they’ll be bigger.

Harvesting New Potatoes

After about a month and a half, around 50-55 days after sowing, potatoes will have formed and this is the earliest they can be harvested. Around this time is when you can start to harvest to have potatoes ready to be eaten right away.

As soon as your potato plant starts to flower, you know the potatoes have formed. This is the first sign that the plant has created potatoes and is your indicator that harvest season has begun. At this time the potatoes will be very small, just a few inches in length, because they just began forming.

If you would like an extended period of harvesting new, ready to use, potatoes you can stagger when you plant them so that you have smaller potatoes all throughout the end of summer. However, it’s not that you can only eat new potatoes- you can eat the larger potatoes that you harvest later in the season, they just need to be cured before eating.

Harvesting Storage Potatoes

Storage potatoes are often called main-crop potatoes, because these are the potatoes that are most often sold at grocery stores and markets. That’s because these potatoes are harvested later, so they’re larger and have matured more.

For full-size storage potatoes, you’ll need to wait a full three months after sowing the seed potatoes. At this point they’ll be completely ripe and will be better for storing for the next few months.

Storage potatoes are typically harvested in September through to October, depending on the climate you live in. Potatoes definitely need to be harvested after the first frost, so you can use this as an indicator that applies to every climate.

The clearest way to know when the full-size potatoes are ready for harvest is when the green foliage dies. You don’t need to wait until they’re completely died off, but this is the latest you should wait until.

If you wait too long after the foliage is dead, the potatoes may start sprouting on their own or could begin to rot in the ground. Later in this article I’ll explain in more detail how to use the foliage to indicate potato size and ripeness.

The Harvesting Process

Regardless of whether you’re harvesting new or storage potatoes, you’ll go about it the same way. Like I mentioned already, the latest that you can wait until harvesting is just up to the first frost- if you wait too long after this the potatoes won’t be good at all.

You’ll need to dig up the potatoes, and for this it’s best to use a pitchfork or a digging fork, rather than a shovel, which is more likely to damage the potatoes. Some people also really like to just dig in with their hands, that way you can feel where the potatoes are.

You need to dig up the first several inches of soil, because the potatoes grow off of the roots so it’s necessary to uproot the entire plant. This is where you need to be careful with your digging tool– while digging up the soil you might pierce one of the potatoes. If this happens, the potato is still okay to eat, but needs to be eaten soon before it begins to rot.

Once you’ve lifted up the first layer of soil, then you need to start digging for the potatoes. They don’t grow in any uniform way, so you really have to hunt in the dirt for them- it’s like searching for treasure! Many gardeners like to get their kids involved with this step and make it a kind of game.

For digging up the potatoes, most gardeners go in directly with their hands (with or without gloves), simply because it’s easier and more direct. Plus, you don’t need to worry about any more roots, you just take them out of the ground.

Also, it’s best to harvest potatoes on a dry day to help them store better. Along with the inconvenience of working in the rain, harvesting while it’s raining or has recently rained will make the potatoes more moist and might lead to rotting while they’re stored away.

If You’re Harvesting From Straw Beds

Potatoes are another vegetable that grows really well with the straw bale method for mulching. Since the straw makes up the top layer of the bed, you won’t have to dig as much up. This means the potatoes will be closer to the top and you just need to remove the straw layer, plus maybe the top one or two inches of soil.

This also means the process will be easier and a bit cleaner, since there’s less dirt you’ll be digging up. This method is preferred by many gardeners who are working with a smaller area to grow in.

If You’re Harvesting From Containers

It’s quite popular to grow potatoes in containers since they are more prone to diseases and can cause disease to spread throughout your garden. Using small containers also makes harvesting much easier.

For the smaller, new potatoes, you can just reach in and feel around for some potatoes and often can grab them directly out of the container. After this, add some fertilizer- like fresh compost or worm castings– on top to promote growth for the rest of the potatoes in the container.

For a complete harvest, you can simply overturn the container and dump it all out. This way you can easily sift through the dirt and find your potatoes- no digging involved!

A variety of potatoes that naturally has a green color- straight out of the ground!

When to Harvest Potatoes Based on Plant Growth

Something that prevents many people from growing potatoes is that they grow under the soil, and therefore out of sight, so it isn’t as obvious when to harvest them. However, this is just a misconception because the part of the plant that grows above ground tells you everything you need to know!

Foliage

As you’ll observe over the months that your potato plant is growing, the seeds will sprout and grow as a dark green plant above ground. As with most plants with green foliage, as it starts to die the leaves will turn yellow, then brown and eventually wilted. This change of colors is a great indicator for what’s going on underground.

Although you can harvest the potatoes while the plants are completely healthy, most gardeners wait to harvest until the leaves start to die. As I’ve explained, the longer you wait, the larger the potatoes will be.

The ideal time to harvest potatoes is when the leaves have mostly died, but aren’t completely dead. So, when the leaves are mostly brown and wilted, but there are still some yellow and green leaves.

Some gardeners prefer to wait until the tops are completely wilted and dead, as this means that the potatoes have maxed out their size and, since the plant is dead, they won’t grow anymore. If you wait until this point, you just need to stay mindful of your potatoes because if you wait to harvest a few weeks after the plant has died, the potatoes won’t store as well.

The top of a potato plant with healthy green foliage that has begun to flower.

Flowers

The growth of the flowers is also a clear way to know how the potatoes are forming. The plant flowers six to seven weeks after planting, so its progress helps you keep track of the overall growth of the plant.

As soon as the plant flowers you know that the potatoes have formed- at anytime before this there won’t be any potatoes. It’s best to wait about one month after the little white flowers pop up for you to harvest.

In fact, the flowers signify that the plant is at the end of its life cycle, which means the potato growth has just begun. As the potato plant dies, the potatoes grow larger and stronger because, if left in the ground, they will become the seeds for the next year.

Storing Harvested Potatoes

Unless your household regularly consumes lots of potatoes, you’ll probably be storing most of the potatoes that you harvest to be eaten in the following months. This step is important to do properly, otherwise you risk losing a lot of your harvest.

First off, once you harvest the potatoes, you can brush off the dirt on their skin, but don’t wash them yet. Only wash the potatoes when you’re ready to use them, otherwise the moisture will soak in and the potatoes won’t be able to store for as long.

After the harvest, the potatoes need to cure for roughly two weeks before they can be used. For this, let all the potatoes sit out on a piece of cardboard or newspaper- something dry that will soak up the moisture- in a room that’s 45 to 60 degrees Fahrenheit.

Once cured, they can be stored in a cardboard box or brown paper bags covered with newspaper. Potatoes need to be stored in a dark and dry space to optimize the time they can be stored for.

If the potatoes are exposed to light or are in a warm place, this will speed up the process of them turning green and sprouting. At this point they’re no longer good for cooking and can cause serious digestive problems like vomiting and diarrhea.

Harvesting Tips

Lastly, here are some harvesting tips that experienced gardeners have picked up over the years.

Once the potato plant flowers, stop watering it to speed up the process of the potato ripening. The flower signifies that the potatoes have begun and the plant is dying anyways, so it’s not necessary to keep watering. Plus, this will help the potatoes harden and this increases their length for storage.

You can tell how mature the potatoes are from their skins right when you harvest them. If the potato skins are soft and come off very easily, this means they’re still young and should be left to ripen for two more weeks, at least. You can eat potatoes like this, but should eat them soon and shouldn’t store them.

After you’ve harvested the potatoes, plant a winter vegetable in the same spot to keep the soil active and healthy- if you’re familiar with crop rotation, this is the same idea. You don’t want the soil to become dormant during the winter months and not be as nutritious in the spring when you’re ready to plant again.

Prepare for Harvest!

If you were previously unsure about growing potatoes since all the growth happens underground, I hope that this article reassured you that you can get all the information you need from the foliage growth above ground.

You should also feel confident knowing that there isn’t a specific, narrow time period when the potatoes need to be harvested. You have roughly a two month period in which you can harvest your potatoes, so if you’re occupied with other things you don’t need to worry about your potatoes!

The more experience you have with growing potatoes, the more comfortable you will become with knowing when to harvest. This is ultimately determined by how large you want your potatoes to be, and how many you want for immediate use versus for storage.

So, it’s essentially up to you to decide when to harvest and these yummy vegetables are very low maintenance when it comes to harvesting. Happy harvesting!