Blueberries need cold winters


New Hampshire Public Radio

Published: 01-11-2023 8:43 PM

Bill Bartlett and his wife have owned Bartlett’s Blueberry Farm in Newport for 38 years. And he says he’s seen winters change a lot over that time.

“We have far more milder days than we used to,” he said. “We rarely get temperatures much below 10 above. Now that would be cold to us, where in the beginning, it wouldn’t be uncommon at all for it to be 15 below, 20 below.”

With climate change, New Hampshire’s winters are getting shorter and warmer. As a consequence, the growing season for many crops is getting longer. But for farmers like Bartlett, cold winters are important for their products.

Some fruit trees and bushes need a certain amount of cold each year to get ready to grow well in the spring. Blueberries, for example, need up to 1,000 hours below about 45 degrees, and brief warm spells can interfere with that.

The volatility of winter temperatures has made Bartlett concerned for his plants.

“We’ve had a few cold days, so now these plants start thinking, ‘Oh, I got to get my gloves out and my mittens on,’ ” he said. “They prepare themselves for more cold weather. Then all of a sudden we hear we have 50, 60 degrees again. That is not good for not only blueberries, but many other plants that live here in the northeast.”

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A milder winter, Bartlett says, could mean a less productive spring for his blueberries. He’s seen climate change affect his farm in other ways, too.

“Climate change can also mean drought for some areas,” he said. “We have a drip irrigation system here so we can water the whole season if we need to. And in the past few years we have done that. This summer we watered about every four days because it was dry.”

Short-term droughts are likely to increase in New Hampshire, according to the state’s most recent climate assessment, as the state as a whole trends hotter and wetter.

Bartlett says there are other varieties of blueberries he could plant that are adapted to different kinds of weather, but they would take about eight years to start producing fruit on his farm. So for now, he’s hoping to see some snow and colder temperatures this winter.

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