Maine’s weather extremes are messing with plants


It’s been a confusing year for flowering plants in Maine.

Wild temperature swings at the end of last season and the start of this one have wreaked havoc with plants’ dormancy cycles.

After a string of 70-degree days in November, gardeners and homesteaders around the state reported seeing plants sprouting and buds opening on trees and plants that should have been well into winter dormancy. At the time, it was predicted crops such as blueberries and apples could see some die-off this spring from the confusion.

Fast forward to early April, when the temperatures shot up to as high as 70 degrees one day.

When daytime temperatures get too high too early, there’s a risk that plants will prematurely form new growth, and that the growth will be killed by frosts at night. Thankfully, a string of below-average temperatures in late April has hopefully prevented a mass die-off.

The ongoing extreme weather events and fluctuating temperatures are signs of climate change affecting the growing season here, which will continue over time. Climate experts warn Maine farmers need to adapt storage techniques, irrigation, crop rotation and types of crops grown here due to the changing climate.

If April’s temperatures hadn’t cooled back down, it could have been disastrous, according to David Handley, professor at University of Maine’s fruit and vegetable research center at Highmoor Farm.

“It was really warm early and that got us scared,” Handley said. “I was out walking my dog and saw my apple buds were already breaking and that is not good.”

In botanical terms, “breaking” is when the new buds of spring start to open and form leaves, flowers or twigs.

It also leaves that new growth susceptible to killing frosts.

“When buds open that early and start to get flowers that can be killed by frost, those flowers will not go on to produce fruit,” Handley said.

There is always a risk of a killing frost in Maine through May. Gardeners or homesteaders who put plants in the ground and see sprouts should cover them at night to protect them from freezing temperatures.

Luckily, more seasonable and colder temperatures have slowed things down.

“This long cool spell we’ve had has swung the pendulum the other way,” Handley said. “Things are now right where they should be.”

Not that growers can breathe a complete sigh of relief.

“This time of year the buds are like coiled springs and with any warm weather they will break dormancy and explode out,” Handley said. “We want them to slow down because we still have the likelihood for a killing frost and it’s going to come down to what the next three weeks look like.”

Looking ahead, temperatures in central Maine will be in the high 50s to low 60s during the day and drop down into the 30s at night.

Even though some fruit-producing trees and plants already have tiny leaves out, Handley said they can handle a light frost.

“If we get that frost three weeks from now, you could lose a crop,” he said. “That’s why farming is so much ‘fun,’ it’s such a gamble.”

One strawberry grower told Handley he’s placed irrigation sprinklers in his fields already. Watering crops during a freeze can save plants. When water on the plant starts to freeze, it releases just enough heat to keep the plant itself from freezing.

“That strawberry farmer told me if the temperatures hit [33-degrees Fahrenheit] he’s turning on his sprinklers,” Handley said.

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