How long do potatoes take from start to finish?

Potatoes are one of the easiest vegetables to grow producing heavy yields of tasty tubers when planted in garden beds and containers. Plus, there’s so many awesome potato varieties to grow – from fingerlings to russets – in a rainbow of colors. But as the crop is produced below ground, it’s hard to tell when the tubers are ready to dig. So, how DO you know when to harvest potatoes? 

When to harvest potatoes? 

Harvesting potatoes is so much fun, even the kids will want to help. It’s like digging for buried treasure – treasure you can eat! There are two main types of potatoes: new potatoes and storage potatoes, and both harvesting time and techniques differ between the two types. Because I want both new potatoes for summer cooking and storage potatoes for fall and winter, I plant at least one bed of each. Figuring out when to harvest potatoes can be a challenge for new gardeners, but once you know the basics, timing the harvest is a snap!

New Potatoes – All potatoes can be new potatoes if harvested when the tubers are still small and thin-skinned, about 50 to 55 days from planting the seed potatoes for early maturing varieties. The first sign that new potatoes have formed is the appearance of the flowers. At that point, feel free to start harvesting from the potato plants. For a long harvest of new potatoes, stagger your seed potato plantings or plant early and late maturing varieties. That way you can enjoy tender new potatoes from late June through August. 

Storage Potatoes – Storage potatoes, also called main-crop potatoes, are ready at the end of the growing season when the foliage has turned yellow and begun to dry, often after a frost. At this point they have reached maturity. In my zone 5B garden I harvest my storage potatoes in late September through October. Some gardeners cut back the leaves while others allow them to die back naturally. Either way, the tubers need to be left in the ground for about two more weeks. This allows the skins to thicken up and results in better storage quality. 

How to harvest potatoes

Pick a dry day to harvest potatoes as moisture can spread disease and rot. What’s the best way to harvest? Carefully! Try to avoid piercing or slicing the potatoes when digging the tubers. If your spade does slip, eat damaged potatoes right away. I find it handy to keep a bowl nearby for damaged tubers which then head directly to the kitchen. Potato scab is a common potato disease and any affected potatoes are also taken to the kitchen as they may not store well.

New Potatoes – When the plants begin to flower, usually sometime in July, you can start harvesting new potatoes by reaching into the side of the hill and taking a few tubers from each plant. I use a gloved hand, not a tool, for this task as I don’t want to damage the plants and I want to keep my hands (relatively) clean. Once you’ve harvested a few new potatoes, push the soil back in place and mound it around the plants. 

Storage Potatoes – To harvest storage potatoes, insert a garden fork about a foot away from the plant and gently lift the root mass. Shovels may also be used. There may still be a few potatoes in the ground, so use a gloved hand to feel around for any missed tubers. Once harvested, gently brush off caked on soil and allow them to dry off for an hour or so outdoors. Do not wash the tubers. 

Harvesting potatoes from containers and straw beds

If harvesting new potatoes from a container or potato grow bag, reach into the soil to feel around for the tubers, taking just a few from each plant at any one time. After harvesting new potatoes from in-ground or container plants, feed them with a fish emulsion fertilizer to encourage healthy growth and more tubers. Container grown storage potatoes can be easily harvested by dumping the container onto a tarp or in a wheelbarrow. Sift through the soil with your hands to grab all of the tubers. Learn how to grow potatoes in containers in this short video. 

If harvesting potatoes from a bed mulched with straw, use a garden fork to carefully lift off the layer of straw. Most of the tubers will have formed in the straw mulch and be dirt-free. Gather them up for curing.

Prepare the soil for next year

Once the potatoes have been harvested, I sow a cover crop or add a source of organic matter, like manure or compost, to the top of the bed. The autumn and winter weather will work it down into the top few inches of soil. If you’re not sure of your soil pH, this is also an ideal time for a soil test. It’s also important to consider crop rotation and keep track of where you grew potato family crops, like tomatoes, peppers, and eggplant. Planting these crops on a 3 year rotation cycle can reduce pests and soil-borne diseases.

How to store potatoes

Before they can be stored, potatoes need to go through a curing process. This helps the skin thicken up and extends the storage life of the tubers. To cure potatoes, lay them on newspaper, trays, or cardboard in a cool, dark spot (50 to 60 F, 10 to 15 C) with high humidity for one to two weeks. Pick a location that offers good air circulation. 

Once cured, move the potatoes (removing any that have signs of damage) to bushel baskets, cardboard boxes (with ventilation holes poked in the sides), low baskets, or brown paper bags. You can also find multiple drawer harvest storage at many garden supply stores. Don’t pile them too deeply, however as that can encourage rot to spread. Cover containers with cardboard or sheets of newspaper to block light. Light turns the tubers green and green potatoes contain solanine, a toxic alkaloid.

The best storage area for potatoes

The storage area should be cooler than the curing site and be dark and well-ventilated. I use a corner of my basement, but a root cellar is best if you have one. You can also store potatoes in a garage, but it should stay above freezing. Aim for the ideal temperature of 40 to 45 F (4.5 to 7 C) with high humidity. Under ideal conditions, storage potatoes can retain quality for six to eight months in long-term storage. Check tubers regularly and remove any that show signs of rot or shrivelling. 

The thin skin that makes new potatoes so appealing limits their storage life to weeks not months. Therefore, enjoy new potatoes soon after harvesting them.

For a tutorial on when to harvest potatoes and how to do it right, check out this video by Savvy’s Jessica Walliser.

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