Flowering trees today, frozen blooms tomorrow | St. Louis Public Radio

Flowering trees today, frozen blooms tomorrow

Mar 9, 2017

The unusually warm winter in and around St. Louis has caused many flowering plants and trees, such as magnolias and peach blossoms, to bloom early this year.

But with temperatures expected to fall below freezing this weekend, experts are concerned it will affect the growing things that already seem to think it's spring.

"The cold snap this weekend is a concern for some of the trees that begin flowering earliest in the spring," said Simeon Wright, a forest pathologist with the Missouri Department of Conservation. "We may see some browning or blackening of flowers as a result of the freeze." 

During the winter, plant cells are dormant, he said. When temperatures rise to warm, spring-like levels, sap enters plant tissues, giving the plant the moisture needed to grow leaves and flowers.

Yet, when temperatures suddenly drop to below freezing, it causes the sap to freeze as well. Then, plant tissue bursts, thus hurting the plant's ability to develop. 

Wright added that damage from cold snaps can make plants more susceptible to diseases. 

The chilly weather will mainly affect flowering plants and trees that produce fruit, such as peaches. 

"If we do get down to the 20s, that will kill the ovary of the [peach blossom], which means you will inevitably lose your fruit crop for the season," said Jennifer Smock, supervisor of the Kemper Center for Home Gardening at the Missouri Botanical Garden. 

Smock recommends that gardeners cover their trees and small flowering plants this weekend. She offered the following tips: 

  • Don't use plastic. Use a cloth-like fabric, like bedsheets. When covering the tree, make sure that the fabric touches the ground to best retain heat. 
  • If you've moved containers of plants from inside to outside, move them back inside. 
  • If you uncovered mulch from your roses, make sure to cover up the crowns of the roses. A little tip dieback, or when new growths become rotten, is fine, but as long as the crowns are covered, the roses will still bloom. 

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