Potatoes can be a bit challenging to grow because you can’t keep an eye on them; often, what you see above ground isn’t even an accurate indicator of what the potato itself looks like. Even if the stalk looks strong, the potato can come out tiny or even rotten. Because of this, it’s really easy to make mistakes with potatoes without even realizing it.

We asked three pros what’s the most common mistake people make when growing potatoes, plus some tips for how to get it right every time.

The Most Common Mistake for Growing Potatoes

While there are many mistakes a person can make when growing potatoes, all our experts agreed that soil issues are an all-too-frequent one.

“If potatoes are exposed to cold and wet soil conditions, it can cause decay,” says agriculture expert Frank Clarke.

Cold and wet soil can come as a result of either overwatering or poorly draining soil. Clarke suggests mixing compost into heavy soils, like those with a high clay content, or switching to containers if your soil is beyond repair.

Soil conditions go deeper than just density. Master gardener Linda Wimmer has the perfect formula for growing potatoes.

“Make sure [you] plant in well-drained (not heavy clay), fertile, slightly acidic soil (pH of 5.8-6.5), 4 to 6 inches deep, 12-18 inches apart with six hours of daylight each day,” she says.

These conditions account for more than just the potatoes growing underground; the whole plant’s health is important for a successful crop.

“Planting too close encourages foliar diseases as the leaves have a hard time drying after a rain or a dew,” says professor of horticulture Steve Reiners.

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Other Problem Areas With Potatoes

Soil conditions are crucial to growing nice potatoes for various reasons, but it’s important to make sure you’re meeting all of the care requirements of these plants. These are some other problem areas our pros often see, plus how to correct them.

Temperature Control

Potatoes can be confusing—they’re planted in the spring, but still considered cool-weather crops.

“Plant when soil temperatures are 50 degrees or above,” Clarke says.

Wimmer says a good rule of thumb is to plant a week or two before the last frost, but to always have an eye on the thermometer.

“Potatoes don’t like anything above 80 degrees and nighttime temps of around 55 degrees,” she says. “Excessive heat can cause potato plants to grow huge above ground but yield no potatoes below ground.”

Not Deep Enough

If potatoes are in the ground, they should be good, right? Wrong. Potatoes should be planted at least 3 to 4 inches deep.

“Developing tubers that are exposed to light can turn green and inedible,” Reiner says. “‘Hill’ the plants by pushing soil over the crowns to ensure tubers are well covered and shaded to reduce green spuds.”

This is a common technique when caring for potatoes, and everyone has their own method. Clarke shares his own with us.

“When the potato plant is 6 inches tall, create a hill around the plant so about 4 to 5 inches of the plant is buried. You will hill the plant two to three times more in the season,” he says.

Grocery Store Potatoes

While you can grow potatoes straight from the produce you purchased at the grocery store, they don’t always provide the most promising yield. Instead, our pros recommend buying and planting tubers themselves.

“if you want the best yields, gardeners should purchase seed potatoes. These are not actual seeds; rather, they are tubers,” Clarke says. “Seed potatoes will grow more vigorously, be longer lived, and produce higher yields.”

Reiners adds that planting grocery store potatoes could introduce foreign plant diseases.

More Potato Problems

If your potatoes are still not turning out how you like, our experts say it could be because of any of these factors:

• Low nutrient levels
• Drought stress
• Over or underwatering
• Planting too late
• Early harvesting
• Pests
• Plant diseases (like late blight)