The Simple Potato-Growing Trick to Start in June for a Much Bigger Harvest

Potatoes are among the simplest vegetables to grow, but a step often forgotten or neglected is earthing them up. It is as simple as regularly drawing soil, straw, or other materials around the plants to encourage more shoots and tubers to develop. Yes, it is a bit of extra maintenance, but it more than pays off come harvest time.

This simple task goes by several names; depending on where you grow your crops, it may be known as earthing, mounding, or hilling up potatoes. No matter what you call it, it is a really important part of growing potatoes, as it gives you a better yield. If you bypass hilling up potatoes, you end up with fewer potatoes to harvest and are more likely to have inedible green tubers.

Experienced growers are likely to earth up potatoes with regularity. Those new to it may look at others covering healthy potato plants with soil with confusion, or see this traditional step in the process as unnecessary. It is vital, though, and you should earth up potatoes in the ground, as well as those in raised beds, pots, buckets, or grow bags.

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Why Growers Earth up Potatoes

Early in the potato growing calendar, the key jobs are chitting tubers and planting them at the right time in spring. After you plant potato tubers in the ground, you usually need to do very little until stems show through the soil – except watering the crop during an unusually dry spell.

Once they do show, hilling up offers several advantages, and you should do it with all types of potatoes.

Primarily, there is more space for side shoots, which means more tubers to harvest. When you earth up potatoes, you give the plant space to grow extra tubers from the buried parts of the stems, increasing your total yield come the end of the season.

As tubers develop, they can get pushed upwards and break through the soil surface. This is not ideal; you want tubers to develop in the dark. If the tubers are exposed to light, they turn green and inedible.

Green potatoes contain poisonous toxins and need to be discarded. By hilling up potatoes regularly, the tubers remain covered as they develop. Covering them prevents greening, so your tubers stay edible, and helps you grow bigger potatoes.

When you earth up potatoes, it also protects young shoots from late frosts and smothers weeds that may pop up around your crop. Potato crops can recover from light frosts, though it sets them back, but deep frosts can signal the end for the plants. If a frost is forecast, hilling up potatoes prevents unnecessary harm.

When to Earth up Potatoes

Don’t start hilling up potatoes too early. Just as placing the tubers too deep is a potato planting mistake, covering them with extra soil too early is too. It can delay the emergence of stems and create an unnecessarily thick layer that young stems may struggle to break through.

The right time is when the plants reach 6 to 8 inches tall. Whenever I see the stems showing that much from the soil in my vegetable garden, I know it is time to head out and earth up potatoes.

You should do the task every few weeks, each time once the plants poke that same amount out of the pile of earth. I usually earth up potatoes three times during the season, but, depending on their growth, some gardeners may do it a fourth.

If you ever see the ground heaving around plants or tubers starting to show through the soil, it is beneficial to mound around the plants to prevent issues.

How to Earth up Potatoes

The easiest way to earth up potatoes is to use the soil around the plants and drag it up around them. Draw the soil up and pile it around the stems, leaving just an inch or two of stems poking out the top of the mound, and gently pack the soil down around the plants.

I would say that the best tool for hilling up potatoes (and my go-to gardening tool for this task) is a garden hoe, more specifically a draw hoe, like this garden hoe at Lowe’s. This type of hoe has a metal head attached at a right angle to the handle, and it is ideal for breaking up and drawing soil around the plants.

Alternatively, I have used a garden spade (like this steel spade at Ace Hardware) before to scoop dirt from between the rows of potatoes and draw it around my potato plants. This tactic works, but you do need to be careful not to remove too much soil too close to the plants.

Or, if you don’t have a hoe or spade to hand, you could use a sturdy metal rake (ideally one like this steel bow rake, also at Ace Hardware) to drag soil into piles.

The Best Materials for Hilling up Potatoes

As mentioned above, using soil is the easiest and most obvious way to earth up potatoes. The resource is close by and easy to draw into place around plants. But there are other alternatives for hilling up potatoes that some gardeners may want to consider:

• Compost is one choice, such as shop-bought compost like this at premium organic compost at Walmart. I have used compost for this task when growing potatoes in containers (I go into detail about hilling up potatoes in pots below). It might end up costly to use compost for long rows of potatoes, so it may only be a realistic option for a few potato plants.
• Grass clippings can be used to earth up potatoes. If you ever wonder what to do with grass clippings after mowing, one potential is to use for hilling up potatoes. Let them dry for a day or two, and then apply them to your potatoes in thin layers, usually just an inch or two thick at a time.
• Straw is another natural material that gardeners can use for earthing up potatoes. It is important to use straw, not hay, as the latter can harbor unwanted grass and weed seeds. You can get a box of USA pine straw at Lowe's. Cover the stems as they appear and wet the straw to keep it in place. One advantage of hilling up potatoes with straw is that it makes harvesting potatoes easier than digging through lots of soil.

FAQs

How Do I Earth up Potatoes in Containers?

If you grow potatoes in a bucket, pot, or grow bag, there is an easy way to earth up potatoes. Start the process off by covering your planted potatoes with a few inches of soil. Once the stems have grown through the soil, cover them with more compost, and repeat this until the container is full. This regular process of hilling potatoes in containers helps you get the best yields.

Hilling up potatoes helps you have strong yields, but so does feeding the crop. For the best results, start fertilizing potatoes ahead of planting. A great way to do this is to add a slow-release all-purpose fertilizer to the site, such as this organic all-purpose granular plant food at Burpee. You can also feed plants once you start earthing up with a tomato feed high in phosphorus and potassium. Do this every two or three weeks until the month before you intend to harvest the crop.

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