Wondering how deep to plant potatoes? This is a great question as planting depth is important. If seed potatoes are planted too shallow, the tubers can turn green and taste bitter. Potatoes planted too deep can rot before they have a chance to grow. Below you’ll learn how deep to plant potatoes in garden beds, in straw, and in pots, and I’ll also share a deep planting technique that can save you time. Keep reading to learn more.
Why it’s important to know how deep to plant potatoes
Potatoes are a popular vegetable grown in home gardens and related to tomatoes and peppers. I plant potatoes for a crop of tender new potatoes in mid to late summer and for a storage crop for autumn and winter. There are several categories of potatoes you can grow including fingerling, russets, and waxy potatoes. You’ll even discover that there’s a rainbow of spuds available from garden centres and online garden shops that includes yellow, white, blue, and red potatoes.
It’s important to understand proper spacing when planting seed potatoes, but it’s also essential to know how deep to plant the tubers. Planting at the right depth increases yield, but also prevents the tubers from turning green. This occurs when tubers form at the soil surface and are exposed to sunlight. Green potatoes contain a chemical called solanine and have a bitter flavor. They can even make you sick as solanine is toxic in large quantities.
It’s not just shallow planting that can impact potato production and quality. Planting seed potatoes too deeply can cause the newly planted tubers to rot. There are three main options for how deep to plant potatoes. I’ve got all the details below.
3 options for how deep to plant potatoes
When you grow potatoes it’s important to plant the tubers at the right depth. Here are three easy options:
- Plant 4 to 5 inches deep
- Plant shallow using a straw mulch
- Plant deeply, but your soil must be loose and well-draining
Let’s look more closely at each of these planting options.
Option 1: Planting potatoes 4 to 5 inches deep
This is the standard technique used when planting seed potatoes with the tubers usually planted in a trench. I use a garden hoe to dig a 4 to 5 inch deep trench and place a seed potato every 10 to 12 inches. Space rows 18 to 24 inches apart. After all the seed potatoes are planted, I use my hoe to backfill the excavated soil. With this method, it typically takes 2 to 3 weeks for the plants to emerge. You’ll also need to ‘hill’ potato plants several times over the growing season. Below you’ll learn more about when and how to hill potato plants.
Option 2: Planting potatoes in a straw mulch
This technique uses a shallow planting depth and relies on a layer of straw mulch to shade developing tubers from the sun. I’ve used this planting option many times, creating shallow potato beds by spreading out the old potting mix from last year’s containers. You can also use this method in raised beds or in-ground gardens.
Once you’ve prepped the site with compost and organic fertilizer, gently press each seed potato into the soil. It should be level or just under the surface of the soil. 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.
Option 3: Deep planting seed potatoes
This lesser practiced technique works best in raised beds or in-ground gardens that have deep, loose, well-draining soil. 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. First, when you plant seed potatoes deeply, you don’t have to hill them during the growing season. Nor do you need to add a layer of mulch. This saves time and effort. However, because the tubers are planted deeply, the shoots are slow to emerge. It could be 4 to 5 weeks before you see the foliage poking through the soil. A few other considerations are soil type and weather. If your soil is clay based or compacted, or the weather has been very cool and damp, deep planting can cause the seed potatoes to rot. It also takes more effort to dig the tubers at the end of the season as they form further down in the soil.
How deep to plant potatoes in containers
In addition to growing potatoes in raised beds, you can also grow potatoes in a pot, barrel, or planter, or plant in bins, buckets, or fabric containers. One of the benefits of growing in pots is no weeds! Plus, it’s an easy way to enjoy a homegrown potato harvest. The number of seed potatoes in the pot depends on how much soil it holds. I like to give each potato plant at least 2 1/2 to 3 gallons of growing space. That means a 5 gallon bucket holds 2 seed potatoes. Overcrowding potatoes in pots results in fewer and smaller spuds.
Ensure whatever pot you use has drainage holes and fill it with a blend of high quality potting mix and compost. I also add a granular organic vegetable fertilizer. Place enough growing medium in the container to fill the bottom third. Lay the seed potatoes on the potting mix and cover with an additional 2 inches of soil. When the potato vines are 6 to 8 inches tall, add another 4 inches of potting mix to the container. Repeat 1 to 2 more times, or until the soil level has almost reached the top of the container.
It’s essential to keep potted potatoes well watered throughout the growing season. Drought stressed potato plants produce few tubers. Check the moisture level often, deep watering every day or two throughout summer.
When and how to hill up potatoes
As noted above, when you plant potatoes 4 to 5 inches deep you’ll need to hill soil up around the plants several times over the growing season. Why? Mounding soil around the plants ensures the tubers are well buried and not exposed to the sun.
The first hilling takes place when the plants are about 8 to 10 inches tall. Using a rake or garden hoe, pull soil up around the plants. Don’t worry about burying the stems, the plants will be just fine. I like to cover most of the potato plants, leaving just the top 2 inches above the hilled up soil.
The second hilling takes place about 3 weeks later with any loose soil drawn up and around each plant. I use a hoe for this task. I don’t bury the plants as much as I did with the first hilling. Instead I mound about 3 to 4 inches of soil around the plant. Alternatively you can replace this second hilling with a 6 to 8 inch layer of straw mulch.
Do you want to learn more about how deep to plant potatoes? Watch this video:
Potato planting tips
Above I’ve covered several options for how deep to plant potatoes, but it’s also important to plant properly. This means prepping the tubers, getting them in the ground at the right time, and planting to maximize yield. Here are 5 tips to keep in mind when planting seed potatoes:
- Start with certified disease-free seed potatoes – It’s best to buy planting potatoes from a garden centre, don’t use grocery store potatoes. This reduces the risk of disease and gives you a strong start to the growing season. Plus, grocery store potatoes are often treated with a sprout inhibitor which means they won’t grow or won’t grow well if planted.
- Plant potatoes at the right time – Wondering when to plant potatoes? The best time to plant is mid to late spring when the soil temperatures have warmed to at least 40 to 45 F. This is typically 2 to 3 weeks before the last frost date.
- Plant in the best site – Potatoes need plenty of sunlight so plant in full sun. Amend the soil with a source of organic matter like compost. The ideal pH for growing potatoes is in the 4.8 to 5.5 range. Acidic soils reduce the risk of scab.
- Prep the seed potatoes – Before planting, cut seed potatoes into pieces about the size of a chicken egg, ensuring each piece has two eyes. If the seed potatoes are small, you can plant them whole. I cut seed potatoes 2 to 3 days before I intend to plant so the cut sides can dry before planting. This reduces the risk of rot. Use a clean, sharp knife to cut the tubers.
- Eyes up – When planting, position the tubers so that the eyes are pointing up. The eyes are buds where the stems and leaves emerge.