They may look like unripe cherry tomatoes, but in fact these are the fruits of the potato plant. Don’t eat them! They are poisonous. Photo by Tom Atwell

While “stealing” a few new potatoes for dinner a few weeks ago, I was surprised to see berries growing on some of the potato plants.

I say berries, but they looked more like cherry tomatoes that had yet to turn ripe. The fruit appeared on only one variety, “Rose Gold,” which we’d bought a few years ago from Wood Prairie Farm in Aroostook County. We have been saving some as seed potatoes each year since.

That the potato berries looked like green cherry tomatoes isn’t surprising because the two are related. Both belong to the Solanaceae family, which are also known as the nightshades. Potatoes produce blossoms every year – Fort Fairfield in Aroostook County even has its Maine Potato Blossom Festival each July. But while the mostly yellow blossoms on tomatoes regularly produce fruit, the white to pink blossoms on potatoes rarely do.

An article from the Michigan State University Cooperative Extension explained the puzzle. Potatoes bear fruit only in cool growing seasons. In southern Maine, this has been a cool (if way too dry) early summer.

Potato berries are not edible; in fact, they’re poisonous. They contain solanine, which probably wouldn’t kill you but would make you sick. Solanine also forms in potatoes that are left in the sun and turn green.

Having discovered these potato fruits, what to do about them? My initial reaction was to cut them off. The berries might steal energy from the underground tubers, the whole reason we grow potatoes in the first place. My second reaction was, heck, let them grow. I’m curious. I want to see what happens.

Curiosity won out. Fortunately, I was reassured when I read further in the extension article. Leaving the fruit alone, I learned, won’t stunt the tubers’ growth. When ripe, the berries sometimes turn purple and they fall to the ground. They also produce seeds, which, if left to grow for several years, would produce potatoes.

Any such plants would not be the same as the “Rose Gold” potatoes that produced the fruit. To replicate a variety, you need to plant the eyes of saved potatoes. Nor would any new potatoes from the berries’ seed be identical to either parent. In practice, hybridizers are the only people likely to plant the seeds from these potato berries. They’d do so hoping to develop a uniquely colorful or tasty spud to take the market by storm.

Some readers might wonder why I was harvesting potatoes in late June and early July in the first place, instead of in September and October. I just love new potatoes. I eat them barely cooked, sweet and tender, with butter and pepper. They don’t even need salt. New potatoes are the reason I grow potatoes; harvest them by using a trowel to carefully remove soil from the plant’s roots to reveal the small, tender spuds. Growing our own would not be worth the effort for the sort you dig up at the end of the season. Those are available cheaply come fall, although I would miss the unusual varieties like Rose Gold, Red Thumb and Carolina. New potatoes, though, are worth the effort.

One other note: After reading about the process last winter, I tried chitting our potatoes before planting this year. The process involves bringing the seed potatoes out from their dark storage space, cutting them up, and putting them in a warm, sunny room three or four weeks before planting them. The eyes produce small sprouts early, and are supposed to speed production.

It worked. We had our first new potatoes earlier than ever this year.

Tom Atwell is a freelance writer gardening in Cape Elizabeth. He can be contacted at: tomatwell@me.com.