When growing potatoes, it is important to give them the space they need to thrive. Otherwise, you will end up with small potatoes – or no potatoes – despite all your hard work during the growing season.
So, how much depth and space do potatoes need to grow? Each seed potato should be planted 4 inches (10 centimeters) deep. Leave 12 inches (30 centimeters) between potato plants, with 36 inches (0.9 meters) between rows. Potatoes will need 8 inches of loose soil below the surface to allow their roots and tubers to grow. You may also need to add up to 12 inches (30 centimeters) of soil above the surface during the growing season.
Of course, some potato varieties will have deeper and wider root systems than others. If you are growing in a container, it will need to be 24 inches (0.6 meters) tall. Let’s take a closer look at how much depth and space potatoes need to grow.
How Much Depth and Space Do Potatoes Need to Grow?
Potatoes will need smooth soil at a depth of up to 8 inches (20 centimeters) to grow properly. Potato tubers (the part of the plant you harvest and eat!) will grow between 2 and 5 inches (5 and 12.5 centimeters) long, depending on the variety.
Since the entire potato tuber grows underground, you will need to loosen and sift your soil to a depth of at least 8 inches (20 centimeters). To give yourself a little margin of error for deeper-rooted varieties, you might want to loosen and sift the soil to a depth of 12 inches (30 centimeters) or so.
Of course, if you want to set a record, you will need much deeper soil than that. That’s because the world record for the heaviest potato is 8 pounds, 4 ounces!
A potato plant will need 12 inches (30 centimeters) of space around it to grow. This will prevent competition between adjacent plants and their roots.
In any case, potato plants will need smooth, sandy soil in order to grow their best. To find out more about the ideal soil conditions for growing potatoes, read my article here.
The soil you use to grow potatoes should always be free from rocks, roots, hard dirt clumps, and other obstructions that might cause potatoes to grow deformed. You can use a soil sifter to remove this debris from your soil.
The depth of a raised bed (planter box) or grow bag will need to be quite a bit taller than 8 inches. This is because you will need more height to hold the extra soil required for hilling (more detail on hilling later!).
How Deep Should a Raised Bed (or Planter Box or Container) Be For Potatoes?
I recommend a depth of 24 inches (0.6 meters) for a raised bed, planter box, or container to grow potatoes. Here is a breakdown of the depth:
- Bottom 10 inches: this includes space for enough soil to contain potato roots and tubers (the part of the plant you will harvest). This gives you a 2-inch margin for error, just in case your potatoes do really well and the roots grow a little longer than expected!
- Next 12 inches: this includes enough space for “hilling” your potato plants during the growing season. Hilling your potato plants simply means adding extra soil at the base of the plant to keep the tubers covered. Without hilling, some of the tubers will be exposed to sunlight. After exposure to sunlight, the tubers will turn green and produce solanine (a toxic substance that can make you sick).
- Top 2 inches: this includes space for extra material later in the season. For example, you might want to work some fertilizer into the soil, or add a thin layer of mulch on top of the soil to retain water and insulate the soil. This extra space will also prevent you from accidentally spilling soil out of the raised bed. If the soil was filled to the very top of the container, it would be too easy for it to escape due to heavy rain or strong winds.
When hilling your potato plants, wait until the potato plant is 6 inches (15 centimeters) tall. At that point, add 4 inches (10 centimeters) of soil to cover all but the top 2 inches (5 centimeters) of the plant.
You may repeat this process throughout the season. In fact, your hills may end up 12 inches (30 centimeters) above the surface of the soil!
According to Johnny’s Selected Seeds, most of the potatoes will be found in the top 6 inches of soil. This is because potato tubers will grow above the seed potato piece that you planted at the start of the season.
If ergonomics or personal preference demands more height for your raised bed, then you could build it on top of a mound of soil. This would also help with drainage during the rainy season.
You might even use legs to raise up the entire bed even further to suit your needs. I know that knees are often the first to go as you get older – I can already feel it!
For every 1 foot (12 inches or 30 centimeters) of length in your raised bed, you should be able to plant 1 seed potato (12 inches between plants). So, you should be able to plant 4 potatoes in a row inside of a 4 foot long raised bed.
If the width of your raised bed is 2 feet, then you can plant 2 rows of potato plants. This would give you a total of 8 potato plants in a 4 foot long by 2 foot wide raised bed.
To find out how many potatoes you can fit in your raised bed:
- Multiply the length of the raised bed (in feet) by the width of the raised bed (in feet). (Note: this assumes a space of 12 inches between potato plants).
What Size Grow Bag for Potatoes?
I recommend a depth of 16 inches (41 centimeters) for a grow bag to grow potatoes. The breakdown of the depth is similar to that mentioned earlier, but with less “margin for error”:
- Bottom 8 inches: this includes space for enough soil to contain potato roots and tubers (the part of the plant you will harvest).
- Next 6 inches: this includes some space for “hilling” your potato plants during the growing season (as described above).
- Top 2 inches: this includes space for extra material (fertilizer or mulch) later in the season. This extra space also prevents your soil from washing away when you water the potato plants.
For a grow bag with a diameter of 24 inches (51 centimeters), you should expect to fit about 4 potato plants.
If you are looking for grow bags, you can check out the many different sizes available on the Vivosun website. They have 1, 2, 3, and 5 gallon grow bags, with various sizes all the way up to 30 gallons.
Note that the 20, 25, and 30 gallon sizes all have a height of 16 inches (41 centimeters), as recommended above. The diameters of these grow bags are 20, 22, and 24 inches, respectively.
Vivosun Grow Bag Dimensions
How Much Space between Potato Plants? (Planting Seed Potatoes)
When you plant seed potatoes, you should leave about 12 inches (30 centimeters) of space between plants. Cover the seed potatoes with a layer of soil that is 3 inches (7.6 centimeters) thick.
Always sow your seed potatoes directly into the garden. Potatoes do not transplant well after being established, so they should not be started indoors (aside from allowing them to sprout – you can learn more about planting sprouted potatoes here).
Potatoes are a cool-weather crop, and they don’t mind chilly temperatures if you start them outside early. According to the Old Farmer’s Almanac, they can be planted as soon as the soil thaws and can be worked.
What Happens if You Plant Potatoes Too Close Together?
If you plant your seed potatoes too close together, you may end up with small potatoes. Small potatoes are the result of competition between neighboring plants for water and nutrients in the soil.
You may also get small or deformed potatoes when the roots of your potato plants run into obstructions underground. This is much more likely if you forget to remove rocks, sticks, roots, and other debris from the soil before planting (you can do this with a sifter).
Also remember that other plants (including weeds) can compete with potato plants for water and nutrients. Taller plants, such as tomatoes, beans, and corn can easily shade potatoes and block out their sunlight. For this reason, you should pull weeds carefully and avoid planting potatoes too close to other tall crops.
How Much Space between Rows of Potatoes?
When planting in your garden, you should leave 36 inches (0.9 meters) between rows of potatoes. This leaves enough space to walk between rows so that you can pull weeds and water, fertilize, inspect, or harvest your potatoes during the growing season.
When planting potatoes in a raised bed or grow bag, you do not need to leave so much space between rows. This is because you will not be walking on the soil in your raised bed or grow bag!
As long as the raised bed is not too wide, you should be able to reach all of the plants from outside of the raised bed. In this case, you can simply leave 12 inches (30 centimeters) between rows of potatoes in your raised bed.
Now you know exactly how much depth and space potatoes need to grow their best. You also know how deep to plant the seed potatoes, and how to use hilling to protect your potato tubers from the sun.
I hope you found this article helpful – if so, please share it with someone who will find the information useful. Now it’s time to get back out in the garden and make your potatoes grow!