When Are Potatoes Ready To Pick & Tips Before Harvesting

Because potatoes grow under the ground it can be tough to tell the right time to pick them. Fear not, there are a number of ways to tell when your potatoes are ready to pick and a wide window of when potatoes can be picked.

If you know the variety of seed potato you planted then you will know the average length of time until they reach maturity. Combine this knowledge with a watchful eye and when you see the potato plants dying off, turning yellow and brown, it’s time to pick your potatoes.

You can get potatoes earlier in the season by planting an early or mid season variety and harvesting new potatoes. New potatoes are ready to pick any time after your potatoes have flowered but are a better size 2-4 weeks after flowers emerge.

Check out this article on new potatoes to learn more about the best varieties for new potatoes and how to harvest them.

The main pros of new potatoes is you get them early in the season and they have thin skin that doesn’t need to be peeled. The cons are they don’t store well and they’re not as big as they would have been if left to mature.

Before & After Harvesting Mature Potato Plants

If you are harvesting mature potatoes when the plants have turned yellow and brown it’s good practice but not necessary to cut the plants down to a couple inches above the ground two weeks before harvesting.

Doing this signals to the potatoes definitively that the plant is dead and the growing season is over. The skin of the tubers will then toughen up and start the curing process so they will store better.

Another good practice is to slow down watering once the potato plants flowers start to fade and to stop watering completely two weeks before you plan to harvest.

If you’re potatoes are still in the ground when the first hard frost is coming you should go ahead and harvest. If potatoes are still in the ground after a frost get them out to avoid rot.

When harvesting potatoes choose a dry day if possible. If you’ve had an extended wet spell around harvest time then just get them out of the ground.

While pulling potatoes out of the ground try your best not to cut the potatoes as cut potatoes will not store well. Whatever ones become unintentionally damaged put to the side and eat them soon.

As your harvesting avoid letting the potatoes sit in the sun for an extended period of time. If a potato’s skin has turned green it was in direct sunlight for too long.

Small areas of green can be trimmed off but any significantly green potatoes need to be discarded because the sunlight has triggered a chemical reaction making the potatoes inedible.

What Do Potato Plants Look Like When Ready to Harvest?

Potatoes can be harvested as new potatoes about 3 weeks after flowering starts. At this juncture potato plants are green and bushy with flowers on them. Later in the season when potato growth has finished potato plants will turn yellow and brown and eventually start to fall or lean over.

When potato plants have reached the point where growth has stopped and the plant is yellow and brownish the plant can be cut down with an inch or two left above the ground to mark the spot.

This will signal to the tubers underground that growth is definitively stopped and the skin of the potatoes will thicken and toughen.

If you see yellowing of the plants early in the season there could be a nutrition problem, heat stress, or stress from pests.

Colorado potato beetle and temperatures regularly above 85 degrees can harshly affect potato plants. Plants dying off and turning brown or black early in the season indicates disease.

Heat stress is a serious stresser on this cool weather crop that can significantly reduce yields. In this study done by done by the Agriculture and Agri-Food Canada’s (AAFC) Fredericton Research and Development Centre they found that out of 55 potato varieties grown under hot conditions the potato variety that did the best still had a 73% yield reduction by weight.

Use shade cloths or whatever you have around the house to get potato plants out of the intense midday sun when temperatures are regularly above 85 degrees.

Heat stress or pest stress is especially important during flowering and the tuber bulking phase when stress on the plants affects yields more. I use neem oil in the garden to deal with pests.

How Long Can You Leave Potatoes In the Ground?

I live in Michigan and the winters here consistently bring temperatures in the single digits. We commonly find potatoes that have overwintered in the ground that look fine and have volunteer plants pop up where we missed them. But, it’s also common to find withered looking or rotted potatoes that we missed in the fall harvest.

To prevent losing potato yields try and take potatoes out of the ground before a hard frost comes to prevent freezing and cracking of potatoes.

Curing and Storing Potatoes

Curing your harvest of potatoes before storing them will help the skin thicken up further and extend the time they can be stored. While harvesting your potatoes brush the dirt off of them with your hands. Avoid washing the potatoes unless you plan on using them after. If they do get wet let them dry before putting in containers for storage.

Cure your potatoes in a dark area with a temperature between 45-60 degrees, high humidity around 70%, and good air circulation. Potatoes have a high water content and low humidity levels will cause them to shrivel.

Potatoes with small cuts and bruises should heal during curing but at the end of this process sort through the potatoes and discard any blemished, shriveled, or soggy potatoes so you don’t invite disease and rot into your storage area.

You can lay the potatoes out on newspaper or in a cardboard box. If you have lots of potatoes you can put the potatoes in a box with newspaper between layers and holes poked into the sides of the box for air circulation. Don’t stack too many layers on top of each other just 2-3.

For curing and storing a wicker basket or cardboard box with holes poked in it and newspaper placed between layers of potatoes will work.

After curing, potatoes should be stored in a temperature between 40-55 degrees with high humidity. Cold is good but freezing is not good. If stored in an area below 40 degrees the starch in the potatoes will turn to sugar.

If temperatures are cold enough for potatoes to freeze there will be splitting and cracking of the potatoes which will lead to rot. If potatoes are stored in an area with temperatures above 55 degrees or light they will not store as long and could begin to sprout after 2-3 months.

Check on your stored potatoes periodically and remove any rotting or shriveled potatoes and break off sprouts if present. With ideal storage potatoes can last up to 8 months.

How to Store Seed Potatoes

Store seed potatoes the same way you store other potatoes. You can choose the smaller size potatoes to keep as seed potatoes and can get more specific by identifying potatoes you want to store as seed potatoes while harvesting so you can choose spuds that came from high yielding plants.

You can store seed potatoes in the refrigerator if you don’t have an area cool enough to keep them from sprouting. If you do store them in the refrigerator make sure you give them plenty of time to break dormancy and pre-sprout in the spring, 4-6 weeks.

Remember that using seed potatoes from the previous years harvest is fine but it does increase the chance of carrying any disease that affected last years crop over to the next growing year. Some people recommend buying certified seed potatoes every year to avoid any chance of this and even go as far as pulling up volunteer potato plants that sprout from potatoes that stayed in the ground from the previous year.

Please comment with any thoughts or experiences you have with when to pick or storing potatoes!

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