Growing potatoes is rewarding, inexpensive, and fun. These tuber plants can be grown on a large scale, for commercial purposes, or in a backyard garden. Gardeners may opt to plant them in an in-ground garden or a container, but how long can you leave them in the ground?
In cold or moderate climates, potatoes can stay in the ground until late fall or early winter when the soil freezes. Conversely, in warmer temperatures, potatoes run the risk of sprouting. However, these tubers can stay in the soil for up to two weeks after the foliage dies without spoilage.
This article explores the conditions around harvesting potatoes. Read on to learn how long you can leave them in the ground.
Potato Growth Cycle
Before you can think about how long you should leave your potatoes (Solanum tuberosum) in the ground, you need to understand their growth cycle.
From planting to harvesting potatoes, the whole process takes about 3 to 4 months. It begins with the seed potato tubers, which form sprouts referred to as “eyes.” These sprouts then grow into stems and leaves of potato plants.
As the plants grow, they gather more sunlight and begin to develop potato tubers underground, typically before blooming flowers. The tuber finally grows into its mature size, and the plant’s leaves start to die.
When the plant’s foliage dies down completely, the tubers are ready to harvest.
Harvesting Potatoes
Harvesting is the most satisfying part of growing potatoes. You get to uproot the succulent tubers and see the results of your work for the past 90 days. This part is so fun that even the kids will want to join in. It’s like digging up treasure you can eat!
However, you need to know when to harvest them because the potatoes won’t mature if you harvest them too early. On the other hand, if you take too long to harvest, the potatoes might begin sprouting.
When To Harvest Potatoes
The right time to harvest potatoes depends on why you need them.
For example, if you want to reap the tubers for winter storage (known as main crop potatoes), you should observe the weather and the plant for signs. Wait for the plant’s foliage to die completely before you can start harvesting.
You should also factor in the temperature of both the air and soil.
In areas where the air is cool without frost in fall, soil temperature will dictate when you can harvest your tuber. Typically, your soil should be above 45°F (7.22°C) for you to harvest main crop potatoes.
Maincrop potatoes need to develop a tough skin for longer storage. As a result, you should only harvest them when you’re sure that the tuber is mature enough.
On the other hand, the timing is different if you want to harvest potatoes for dinner. Digging up potatoes for dinner is much easier. These are known as new potatoes and don’t need to mature fully. You just need to wait late in the season 50 to 55 days after planting and take only the tubers you need. The first sign you need to look out for is the blooming flowers.
For a long harvest of new potatoes, stagger your seed potato plantings or mix late and early maturing varieties. This way, you can enjoy fresh potatoes from June to August.
Do Potatoes Keep Growing After the Plant Dies?
Potatoes don’t keep growing after the plant dies. The health of a potato’s plant foliage is a clear indication of the growth happening in the tubers. When a potato plant dies back, it cannot continue producing potatoes. The tubers will be stunted, diseased, or immature if it does.
Therefore, a plant with brown leaves will not continue producing potatoes, at least not those you would eat.
How Long To Leave Your Potatoes in the Ground
Generally speaking, leaving your potatoes in the ground is not recommended, especially for long-term storage. Leaving them under a layer of soil that will probably become wet might either cause them to rot or encourage sprouting. Both of these results aren’t good for your produce.
However, you can leave the tubers in the ground for up to two weeks after the potato foliage begins to die. If you take longer than that, the tubers might start sprouting if the soil temperature and moisture support it. Otherwise, they’ll start rotting.
How To Harvest the Potatoes
Now that you know when to harvest potatoes, you need to know how to do it right. The harvesting process must also be meticulous to avoid damaging the precious tubers. It’ll also be determined by whether you’re harvesting new potatoes or maincrop potatoes.
New potatoes are small and tender and do not store well. These should be harvested and eaten right away. You can harvest them using a garden fork or shovel, and if you’re careful, you can replant the plant’s small tubers to grow.
However, if you’re harvesting potatoes for storage, wait until all the foliage has died before you start harvesting. Then, dig up a few tubers to test maturity. If the potatoes’ skins are still thin and light, they’re still “new” and not ready for storage. To encourage faster maturity, cut off the stems and leave the tubers for a few days without water.
When the tubers are mature enough, follow these few simple steps to dig them up:
- Push a garden fork or spade about six inches (15.24 cm) from the base of the plant.
- Lift the plant with the fork and shake off the soil.
- Gather the potatoes and dispose of any that have green skin. (This indicates a toxin called solanine).
- Lift the loose soil near the potato with the spade or garden fork to discover any tubers you might have missed.
- Discard the foliage and the original potato seed to prevent diseases.
The tubers are now ready for storage. However, unlike new potatoes, you shouldn’t wash main crop potatoes after harvesting. While it’s hard to resist the temptation, washing the potatoes introduces moisture to their skins, which is not good for storage.
I recommend watching my YouTube video below if you’re a visual learner. I’ll visually walk you through how long you can leave potatoes in the ground and the telltale signs you need to look out for during this period.
How To Store Potatoes
Storage is another important aspect of growing potatoes. If you store the tubers in the right conditions, they can last for weeks or even months. However, if you expose them to elements like moisture or heat, they will sprout or rot.
Store in a Cool Place
When stored between 43 and 50°F (6.11- 10°C), raw potatoes can go for many months without spoiling. This temperature is slightly higher than refrigeration and can be achieved with basements, cool cellars, sheds, or garages.
These conditions discourage the formation of sprouts, a strong sign of spoilage. As a matter of fact, studies show that potatoes stored in cool conditions had four times the shelf life of potatoes stored under normal conditions.
Further research revealed that potatoes stored in cool conditions retain their vitamin C content longer than those stored at room temperature. Therefore, keeping potatoes at cool temperatures, slightly above refrigeration, is a great way to maintain their vitamin C content and extend their shelf life.
Keep Away From Other Produce
Many fruits and vegetables emit ethylene gas as they ripen. The gas helps them soften and increases their sugar content. However, if you expose potatoes to the gas, they will soften and sprout much faster. Therefore, avoid storing potatoes near ripening vegetables and fruits, especially tomatoes, bananas, onions, and apples.
Although there are no scientific studies to show how far potatoes should be kept from fruits and vegetables, storing them on the other end of a dark room should be enough.
Place in an Open Paper Bag or Bowl
Potatoes need good air circulation to avoid the accumulation of moisture. The best way to achieve this is by placing them in an open airbag or bowl. Don’t store them in an enclosed container with no ventilation, such as lidded glassware or a zipped bag.
With no air circulation, moisture from the tubers will accumulate in the container, promoting the growth of bacteria and mold.
Don’t Store Potatoes in a Freezer or Refrigerator
Although cool temperatures are ideal for potato storage, freezing or refrigeration is not. Freezing potatoes can cause cold-induced sweetening. This is when some of the starch is converted into reducing sugars. These sugars can form carcinogenic chemicals known as acrylamides when the tubers are fried or exposed to very high cooking temperatures.
If you’re curious, check out my article on how to harvest and store the most popular fruits and vegetables: How to Harvest and Store Your Fruits and Vegetables
Keep Some Plants To Use As Seeds
If you plan on replanting potatoes, you can set aside some tubers to use as “seeds.” Then, a few weeks before planting season, bring the potatoes to a warm sunny area and cover them with moistened paper towels or moist burlap. Soon, the potatoes’ eyes will begin to sprout shoots.
When it’s time to plant, you can cut big potatoes into two segments so that each part has a shoot. In a few months, each sprout will produce an entire hill.
To Sum It Up
Leaving potatoes in the ground is not recommended. However, the tubers can stay in the soil for up to two weeks after the foliage dies without spoilage. In cold or moderate climates, the potatoes can even stay up to late fall or early winter without sprouting.
