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How Do You Know When Potatoes Are Ready To Harvest – A Complete Guide

Adding potatoes to your garden can provide a bounty of food that can easily be stored to last a few months. Potatoes are tubers, meaning they grow underground and provide a means of energy and nutrient storage from the aerial parts of the plant. They are not as easy to tell when it is time to harvest as a tomato or bell pepper. How do you know when potatoes are ready to harvest? 

Potatoes are ready to harvest when you notice complete dieback of the foliage. This means the leaves and any flowers present have dried and wilted. What usually would be a bad sign for most fruiting plants, potatoes are a bit different because you want to see the dieback of the plant’s foliage to indicate your potatoes are ready for harvest.

Once dieback has occurred, you can be assured that your potato is packed with nutrients and are ready to be eaten or stored. To harvest young potatoes, wait until your plant begins to flower. 

Continue reading to learn more on how to grow potatoes and how to harvest and store your bounty for maximum yield and flavor. 

How to grow potatoes

Potatoes can be grown easily at almost any time of year, depending on the climate. They can even be grown in containers, making them a very accessible food to have in your home-garden arsenal.

You can use a “seed” potato purchased online if you have a particular type of potato you’d like to grow, or you can use a grocery-store potato that has sprouted. Take caution when using grocery potatoes, as these potatoes are often treated with sprout inhibitors that can prevent growth and can even cause disease in your crop. 

Potatoes with “eyes” can be cut and left out to slightly callous before being planted with the eyes facing up. This can take a couple of days, done in a cool, dark place. Allowing your potatoes to be callous instead of immediately planting mitigates the risk of your tuber piece rotting in the ground before it can sprout.

Cutting the tuber can encourage more sprouting, though you want to have at least one eye or sprout per piece of tuber that you plant.

Grow your potatoes in a sunny spot in fertile, well-draining soil. Granular, slow-release fertilizer can be mixed into the soil before placing your potato pieces. Space out your cut pieces about 12-24 inches apart to allow room to grow since tubers form underground.

Plant the pieces about 6 inches deep into the ground. Water is enough to settle the soil. Take care not to over-water your potato plant, but ensure it doesn’t dry out either. Checking every day or every other day during the warmer months for water should be sufficient. 

Potatoes are hungry plants and require regular fertilization of nitrogen and potassium rich fertilizer during the stage where tubers are being set. The potatoes are where all the nutrients and carbohydrates are stored in the plant, so proper fertilization yields a more nutritious potato. Nitrogen helps with foliage growth and root development, and potassium is essential for the movement of water, sugar, and nutrients throughout the plant.

Mound some soil up a few inches on top of the tuber to protect emerging sprouts from sunburn, known as “hilling.” Tubers exposed to the light can turn green and become inedible, so your harvest needs to ensure your tubers are protected from the light. Once flower formation begins, you will no longer have to worry about hilling since your potatoes are well on their way to maturation. 

From here, it is just maintenance of your plant(s) until the classic sign of harvest: dieback of the aerial parts of the plant.

Ensure you are watering and providing fertilizer through the growing process to ensure you have as many stolons reaching maturity. If you want to harvest some young “new” potatoes, reach underground after the flowering process has begun and pick some potatoes for a taste test. Young potatoes are best in flavor and texture after harvesting and do not hold up well to storage. 

After the foliage has died back, and depending on when you planted your potatoes, you can wait up to two weeks or harvest, or until temperatures cool down, so you don’t have to cure your potatoes inside. About three or four months after planting, you can have enough potatoes to last you through winter, depending on the number of plants grown. 

How to know when to harvest your potatoes

Potatoes may go against gardeners’ intuition when the right time to harvest is after the plant is dead. Tubers are different than fruiting plants, which emerge from flowers because tubers form underground on the roots as a place to store energy and nutrition for the aerial plant. Fruits like strawberries form from the plant’s flower, which requires pollination, and function ultimately to help the plant reproduce. 

Below is a general guide to your potato plant’s stages, from sprout to harvest. 

SproutingSprouts form at the “eyes” of the potato planted underground and make their way to breach the soil. Roots begin anchoring the tuber into the ground.
Early GrowthFoliage and stems begins to emerge; stolons, or runner stems, begin to start forming at this stage as well. The ends of the stolons eventually form their own tubers which can be added to the harvest. 
Tuber InitiationStolon tips swell to show the beginning of tuber formation. At this stage water and nutrient availability are critical to developing these stolons to form full tubers, as not all stolons will reach maturity. 
FloweringFlowers will appear which coincides with the majority of bulking done in tubers. The tubers become the main storage center of energy and nutrients produced by the plant. 
HarvestLeaves and flowers will wilt and turn yellow, with eventual death of any vines or branches above ground present. Potatoes are to be left in the ground to cure until the complete dieback of the plant is reached. 
Growth stages of potatoes

While potatoes can be grown most times of the year, it is best to plant them early to late spring for a harvest right after summer. If you are in an area where the weather gets quite cold for winter, planting late into summer can produce the best results. 

How long do potatoes take to grow? 

Potatoes can be planted in the early spring months of March through May and take from 60 to 120 days, depending on the size of potato desired. 

“New” potatoes refer to young, baby potatoes harvested earlier in the growth stage than full-sized potatoes and are usually collected right after the plant has flowered. These potatoes have a creamier texture and thinner skins, but since they’re immature, they are not great if you have long-term storage. 

Fortunately, with all the potato varieties there are, there is not much variation in the time it takes to grow and harvest. 

The first stage of growth, when your plant begins to sprout from the tuber, takes about 15 to 20 days. The formation of stolons also takes about the same amount of time, and from here, the tubers begin to form for another 15 to 20 days. 

The bulk of grow time is spent growing the tubers, which can take about 45-60 days, depending on weather conditions and water/nutrient availability. Finally, maturation occurs, taking about 20 days until they are ready to harvest. 

Overall, you can expect to harvest your potatoes after about three or four months for full-sized potatoes, and a little sooner for new potatoes, harvested shortly after flowers begin to appear. 

What happens if you harvest your potato plants too early? 

Harvesting your potatoes before they’ve cured underground can lead to premature rot and decrease the storage life of your potatoes. Curing potatoes can be done for up to two weeks after your plant has completely died. Remove the dead foliage and stems and patiently wait for your cured harvest.

If you’ve harvested your potatoes right after the dieback, before they’ve cured underground, you can simulate this stage in your home. Find a cool, dark area (about 50-60ºF) with a good humidity and set your potatoes out on cardboard or paper. Leave them to cure for one to two weeks before use. 

During the curing process, your potato skins thicken, extending their shelf life and perfecting their texture. “New” potatoes or potatoes harvested young do not undergo a curing process since they are still immature and are best eaten shortly after harvest. 

Are green potatoes safe to eat? 

Potatoes exposed to sunlight can turn green, which is a telltale sign that these potatoes are no longer safe to eat. 

Green potatoes are perfect pieces of evidence of improper storage. Green indicates the presence of a group of toxins called glycoalkaloids, which can cause gastrointestinal distress and poisoning symptoms upon consumption. Any bitterness in the flavor of a potato is a good way to tell these glycoalkaloids are present and should be promptly thrown away. 

Potatoes that have sprouted “eyes” are usually safe to eat once the eyes have been cut away provided the potato is not soft or squishy. Sprouted potatoes can be salvaged for planting as well, whereas green potatoes are not recommended to be salvaged at all. 

The best way to prevent the greening of your potatoes is to effectively “hill” your potatoes while they are growing, allowing them to cure after maturity and storing them in a cool, dark place for the remainder of their time before being prepared. 

How to Harvest, Wash, and Store your Potatoes

Part of the beauty of a potato is its ease of preparation and versatility in the kitchen. They are no-fuss foods, and they are no different when harvesting. 

You can use a trowel or hand shovel to dig up your potatoes, or if they are shallow enough, all you’d need is your hands and some gardening gloves. When using tools, take caution to not tear up your harvest before they can be enjoyed. Any damaged potatoes should be used immediately or tossed. 

Your potatoes will emerge covered in soil, which might be tempting to wash off. Instead, brush away excess dirt and store them in a cool, dry place, where your potatoes can stay good for a whopping 6 to 8 months. Wash your potatoes right before use instead of after harvest, as washing after harvest can increase the chance of mold development and decrease the overall shelf-life of your potatoes. 

The best way to store many potatoes is in a cool, dark place to avoid greening or sprouting. Avoid stacking your potatoes too deeply on top of each other, which can encourage rot, and instead opt for shallow storage like in paper bags or wide baskets covered with a tea towel. 

Final Thoughts

Potatoes are easy to have around as they can be planted almost any time of year, and harvests can be quite large from just one plant, as long as it is cared for properly throughout their maturation stage and is cured correctly. 

Curing potatoes increases their shelf life, and when stored properly, this can be up to eight months. Depending on how many potato plants you have, this can be more potatoes than you know what to do with! Sharing your homegrown potatoes with neighbors or friends can be a delightful way to use your harvest and forge relationships with those around you. 

The versatility of these tubers, combined with their ease of growth and harvest, make them perfect for growing in summer or fall months, so you have garden-grown produce available to you during the winter months. Don’t think twice about planting that sprouted potato you have; in a few months’ time, you will not regret your decision.