How Deep Should You Plant Potatoes for a Successful Crop?

Information I’ve Been Missing

What is the relationship between days to maturity and storage length. Should I just stay away from potatoes that are early (70–90 days) or mid-season (90–110 days) if I want to store them until early spring?

• Yes, the varieties that mature later tend to stay dormant longer than the varieties that mature earlier. However, dormancy is controlled by many things, many of which are weather-related and out of the grower’s control. So plant early and mid-season potatoes to eat right away, and late-season potatoes to store for longer.

What really is the optimum planting depth and spacing of my potatoes?

• One to four inches deep is best for planting (less deep in colder areas and more deep in the south). I’ve been planting my potatoes WAY too deep.
• Plants should be 10 to 12 inches apart, except for fingerlings, which should be 14 to 18 inches apart. I’ve been planting my potatoes too far apart.

What is the optimum planting time for potatoes in my area?

• When the ground is 50 degrees four inches deep in the morning, before the sun heats it up, you can plant. If you don’t have a thermometer, this soil temperature map for your zip code is the best way to guess what the temperature of the ground is likely to be. In our area, the ground gets warm enough to walk on in early to mid-April. After the first of the month, I like to plant because there is less chance that a hard frost will kill the new stems.

Does it really matter if the potatoes are determinate or indeterminate? I only learned about the difference between the two a few years ago, and it’s hard to find a list that says for sure which ones are which.

• In short, no. Most commercial varieties are determinate, which means they grow all at once and then die back. They don’t keep putting on potatoes all season. Another important thing to remember is that potatoes are a cool-season crop. If it’s over 90 degrees during the day, the plants will likely die, whether they are determinate or indeterminate. Since summers are getting hotter and longer here, there’s no point in looking for indeterminate types. As the weather gets warmer, I’m also thinking about putting a shade cloth over the row.

What’s with disease issues? Does it really matter if I don’t buy certified seed potatoes every year?

• Viruses can easily infect potatoes. They are spread from plant to plant by insects with sharp, sucking mouths, most often by aphids. As these viruses spread through the potato plant, they slowly lower the yield of the potatoes themselves. Because these viruses build up in the potato tuber, which is a copy of its parent plant, planting potatoes from the previous year means that you are slowly adding more and more viruses. There’s a chance that you’ll never actually SEE that your potatoes have viruses. Over the years, the potatoes will just get smaller and smaller. These viruses are harmless to humans.
• It seems that before tissue culture of seed potatoes became common, some varieties had problems with “running out,” which meant that they couldn’t produce healthy potatoes when they were grown from seeds.
• Here’s a look at how commercial seed potatoes are grown from the outside. Seed potatoes are grown from cuttings instead of real seeds (you can grow potatoes from real seeds, but that’s a different blog post). Instead of coming from the roots, the tubers we harvest come from the plant’s stem. Along the stem there are lateral growth points, or buds. Each of these buds has a meristem, which is a small group of cells that divide quickly and can make all of a flowering plant’s adult parts. Meristems don’t have blood vessels, so they are less likely to get bacterial, fungal, or viral infections. It is possible to grow these meristems in a lab until they turn into small plants. This tissue is tested over and over for disease to make sure it is free of it. They are sometimes called pre-nuclear.
• Then, these plantlets—about the size of an alfalfa sprout—are grown in a greenhouse, away from insects that spread disease, to make “mini” tubers. These plants are the most disease-free seed tubers you can buy. They are sometimes called “nuclear.” Then, these little tubers are grown out in the open field to make the first crop of “seed” potatoes. It is illegal in most states to grow and sell these potatoes for more than one generation at a time, since each generation brings more viruses. Sites that are higher up and have colder climates have fewer insects, so diseases tend to spread more slowly there.
• Most of the time, when you buy seed potatoes, they are “certified.” Different states have different requirements for this certification, but it does make sure that the potatoes you buy are of a certain variety and size, are free of different diseases and mechanical damage (but not always viral diseases), and that the information on the box tells you what generation of grow out the potatoes are. See HERE for USDA details. Washington Dept. of Ag Certification Program HERE.

Wouldn’t it make sense that the larger the starting tuber, the more potatoes you’d get?

• It’s true that bigger potatoes give you more food, but you need to buy more seed potatoes to plant the same area, so it’s a trade-off.

Do I really need to cut up my seeds into individual “eyes”?

• Every potato “eye” grows a stem, and that stem makes a new plant. The best “seed” potato size, according to studies, is between 1 1/2 and 2 3/4 oz. (About the size of a large chicken egg). Because of this, cutting your bigger tubers into 1 1/2 to 2 oz square pieces, each with at least one eye, and spreading them out when you plant will give you the most potatoes for the least amount of work. 1 lb of potatoes should plant 8-10 feet.

What is Chitting or Greensprouting and should I do it?

• To wake a potato up from its sleep, greensprouting is done. To make a potato sprout, bring the seed potatoes to room temperature and keep the plant in the dark for 7–10 days. As soon as sprouts appear from the eye, put the tubers in light and cool them down to 50–55 degrees to stop growth. When you plant seeds, this method cuts the time it takes for the stems to come up by 10 to 14 days. The plant is very good at fighting off rot once the stem has come out. So green sprouting is a great way to protect against disease and save time when it’s time to harvest.

When is the optimum time to harvest my potatoes?

• You may have heard that your plants are making potatoes if they have blooms. Now is very important for your potatoes to grow, and it’s even more important that they have enough water! You can pick a few ping-pong-sized potatoes here and there once you see the plants blooming, but they won’t be at their best size until the plants have died back on their own. This can be anywhere from 70 to 130 days, depending on the type. For me, if I plant on April 15, I could harvest anywhere from late June to late August. Pay attention to those maturity estimates! .

• It’s possible for tubers to get bigger in the last week or two before they die completely. This is because the tuber pulls energy from the plant and stores it in itself. The potatoes will last longer in storage if you harvest them when they are fully grown. Don’t feel like a bad gardener if you don’t dig your potatoes right away (as long as you can keep gophers from eating them all before you do!)
• There are many genetic and environmental factors that make some types of plants stay dormant longer than others. All Blue, Burbank, Butterball, Katahdin, Kennebec, Prairie Blush, Red Chieftain, Red Cloud, Red Pontiac Rose, Finn, Apple, Russian Banana, Fingerling, Sapro, Mira, Yukon Gem, and Yukon Gold are some varieties that are said to store well for a long time.
• Your mileage may vary. The All Blue, Red Chieftain, and Red Pontiac have not done very well in my storage conditions.

What IS the ideal way to store potatoes for home use to keep them from sprouting?

• You’ve probably anways heard to NOT refrigerate your potatoes. This is because some of the starches can turn into sugars when the potato is stored in the fridge. When the potato is deep-fried, the extra sugar can turn it an unattractive shade of brown. I wouldn’t mind if the color changed, and I don’t deep fry potatoes very often anyway. When potatoes are boiled or roasted, this extra sugar doesn’t change the color.
• The University of California Davis says that the best way to store fresh food is at 40 degrees F with high humidity and good airflow. Conditions that don’t generally exist on the homestead. It seems like the best solution would be to keep potatoes in an extra fridge in my garage.

My problem is that I can’t get cheap, large amounts of straw or mulch. I plant up to a 100-foot row of potatoes, so I’d need a LOT of mulch, and I’d have to reapply it several times during the growing season to keep the potatoes from turning green. I used straw as mulch once, and it sprouted a million weed and grass seeds that were impossible to get rid of. What a great idea! If I had a big pile of mulch to use, I would definitely give this more of a try. But it does require deep soil fertility to be successful. Potatoes have surprisingly deep roots and are heavy feeders. If the mulch you plant in hasn’t been composted well before, your potatoes will be hungry and your crop will be small.

So there you have it. A much deeper dive into the ins and outs of growing potatoes for long term homestead use. This year I’ll be better about choosing my potatoes so that they harvest early and then late. I’ll also suck it up and order seed potatoes through the mail. I’ll likely order from Fedco (they carry close to 50 varieties). For early varieties, I’m thinking about Yukon Gem or Caribe. For late varieties, I might choose Kauka Gold, Elba, or Katahdin. I also like Pinto as a fingerling.

© Miles Away Farm 2023, where we’re Miles Away from perfecting our potato growing techniques, but are willing to keep experimenting. Want more content? Sign up for a monthly newsletter to your email inbox HERE

How Deep to Plant Potatoes

FAQ

What month do you plant potatoes?

What is the best depth to plant potatoes?

What’s the secret to growing potatoes?

Do you water potatoes right after planting?

How do you plant potatoes in a raised bed?

Make sure the raised bed is at least 16” deep. If possible, dig out a square foot of soil, leaving a 6” layer on the bottom. Place the potato in the hole, and add another 4” of soil on top. If you can’t remove large portions of soil, plant directly into the raised bed.

How deep should potatoes be planted?

When deep planting potatoes each tuber should be planted 8 to 9 inches deep. You can use a garden hoe to create a deep trench or a shovel to dig planting holes. Place a seed potato every 10 to 12 inches and keep rows 18 to 24 inches apart. Deep planting has several benefits, but there are also a few drawbacks.

How far apart should potatoes be planted?

As with the first option, space each tuber 10 to 12 inches apart and rows 18 to 24 inches apart. After the last seed potato has been placed cover the bed with 8 inches of straw. You won’t need to hill soil up around the plants, but you do need to add more straw about 4 to 6 weeks after planting.

How deep should a potato garden bed be?

Prepping the garden bed is equally important as the potato planting depth. Potatoes do best in rows. Depending on the number of plants, make sure there is enough spacing for at least 12 to 15 inches between each plant. Dig the trenches so that they are six to eight inches deep.