Hard frost poses danger to plants already in bloom

PHOTOGRAPHER: Kelly de la Rocha

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After last week’s taste of summer, Mother Nature is dishing out a strong dose of reality.

Forecasters were predicting lows overnight Monday in the upper teens to lower 20s, and the potential for a drastic drop in the mercury had area gardeners concerned.

The danger to newly awakening plants, shrubs and trees isn’t necessarily a layer of frost on the buds and leaves, but changes that occur internally when temperatures bottom out, said Christian Cash, chairman of SUNY Cobleskill’s Plant Science Department.

Thanks to the unseasonably warm temperatures, plants have come out of dormancy early and have started to move water and nutrients to their buds.

“The chemistry of the plant has changed from protecting itself from winter to now it’s ready for spring,” Cash explained. “The basic change that occurs with the plant is, now there is more water in the cells and the water has the potential to crystallize [at temperatures below freezing] and burst the cells, which would kill the newly formed tissue. It won’t generally kill older tissue.”

Temperatures for tonight aren’t forecast to be much more plant-friendly.

“We’re looking at lows in the mid- to upper 20s,” said Tom Wasula, a meteorologist for the National Weather Service in Albany.

Temperatures should quickly

rebound in the Capital Region on Wednesday, with highs in the upper 40s to mid-50s, he said, but by that time the damage is likely to be done to tender flowers and foliage.

The most vulnerable plants are those that are already in full bloom. But some are tougher than others.

“Daffodils are kind of designed to take the cold, plus they’re lower to the ground and our ground retains heat, so even though you have frost coming down, our thawed-out ground now, it gives some protection,” Cash said.

Blossoms far from the protection of the ground will likely be killed in a hard frost, which, on fruit trees, will mean no fruit.

The 75 acres of apple trees aren’t in full bloom at Knight Orchards in Burnt Hills, but they are in various stages of budding.

“When [the buds are] where they’re at right now, we don’t like to see it go much below the high 20s. They’ll take a bit lower at the stage they’re at right now, but not much more, so I don’t really want to see it go much below 28, 29,” said owner Jeremy Knight.

But if the temperature does dip lower, there’s really nothing that can be done to save the delicate buds, he said.

“Usually later in the season, say if it was May, end of April … you have a layer of [warmer] air higher up and you’re able to pull it down with a wind machine, but this early in the season, that warm air is just not there,” he said.

Knight is even more concerned for his peach crop.

“I don’t think they’re going to make it. The flowers on those are just about ready to open,” he said.

Isabel Prescott, owner of Riverview Orchards in Rexford, has several thousand apple trees in various stages of budding.

“I’ve never seen us be quite this early before with the budding, so it’s going to be interesting to see the results,” she said.

A hard frost in May 2010 caught the orchard’s trees in full bloom, resulting in the loss of about 85 percent of the apple crop, she said.

Last week, home gardeners were coming into Kulak’s Nursery and Landscaping in Rexford to search for annuals. This week, they’re calling for advice about how to protect their plants from the frost.

“All last week I had customers coming in and asking us, ‘Why hasn’t your nursery got plants in it yet?’ And it’s for exactly what’s going on right now,” said owner John Kulak. “We’re ahead of the growing season by one month, and this is not the growing season. Memorial Day is really the [start of] growing season. You get these things in too early, and one frosty night and you just wasted all your money if you don’t protect them.”

The roller-coaster weather the region is experiencing is highly unusual, Kulak said.

“I’ve been here 45 years and I have never seen a season like we’re having right now,” he said. “There was virtually no frost in the ground this year and there was no snow, and all those play out to be a disaster in the spring, like we’re going through right now.”

Experts agree the best way to protect newly budding plants from cold temperatures is to cover them with a sheet or blanket.

“That traps the heat of the ground near the plant and protects it from the wind drawing the moisture out of the plant,” Cash explained.

But even if foliage and flowers are damaged by frost, the plants will likely survive.

“You’ll more than likely see less flowers than you normally see, or the buds that are on there right now will probably get frosted and fall off,” Kulak said. But leaves that fall will be replaced by new leaves, he said.