Does hilling potatoes increase yield?

QUESTION: What are the benefits to hilling my potatoes? Does hilling potatoes increase yield? -Kayla W.

ANSWER: Hilling is not meant to increase the size of your potato harvest, but instead hilling protects developing potatoes from the elements as they grow. That said, hilling does tend to end up increasing the yield of potato plants because in addition to preventing potatoes from going green, it also controls weeds, improves drainage, and raises the temperature of the soil.

It’s especially important to protect developing tubers from the sunlight, as exposure to the sun can cause potatoes to turn green with the toxic alkaloid solanine, which can poison people if ingested. That’s why it’s important to cut off any green portion of potatoes before consuming them. Symptoms of solanine poisoning include confusion, diarrhea, digestive discomfort, drowsiness, vomiting, shortness of breath, and weak or rapid pulse. Untreated solanine poisoning can eventually lead to death due to respiratory failure.

Is it too late to hill my potatoes?

It’s best to start hilling potatoes once the foliage has grown to eight inches tall, and continue building the hills as plants grow taller throughout the season. Most gardeners hill once at six to eight inches tall and again a second time a few weeks later. Long season potatoes may get a third hilling.

If you missed your window, you can hill your potatoes at a later date, but your results may not be as ideal as they would have been if hilling occurred at the appropriate time. Go ahead and add the hill now to cover your potatoes, though, as the soil protects the developing tubers from sunlight, which can turn them green and raise their solanine content to dangerous levels as described above.