Plants and cold temperatures

Plants and cold temperatures

Ken Johnson

Recently we’ve had some unseasonably warm weather. While this nice weather allowed us to emerge from indoor earlier than normal, it’s dons the same thing for many of our spring blooming bulbs and other plants. The return of more seasonably appropriate temperatures has many people wondering what the fate of their plants will be.

Most of our spring blooming bulbs such as tulips, daffodils and crocus can handle cold temperatures. If they have not begun to bloom, the return of cold weather will often delay further development. If they have begun to bloom, very cold temperatures may damage the blooms. Fortunately, the foliage of these plants is rather hardy and can handle cold temperatures, so they shouldn’t suffer much long-term damage. If you are concerned about you bulbs, you can always cover your plants when below freezing temperatures are predicted.

When it comes to trees and shrubs, most of the ‘problems’ will come in the form of damaged or killed flowers. Newly emerged foliage can also be susceptible to freezing temperatures. However, trees can send out a new flush of leaves if this foliage is damaged or killed. As long as trees are healthy and established, there shouldn’t be any long-term damage to trees, especially if you take good care of them for the remainder of the year (like watering during dry periods). Unfortunately, plants don’t send out new flower buds, so while freezing weather may reduce or eliminate this year’s blooms, there shouldn’t be any long-term damage to trees or shrubs.

Many people are also concerned about their fruit trees. Just like trees and shrubs, freezing temperatures shouldn’t harm healthy and established trees, but blooms can be damaged. As flower buds begin to swell and open, they become increasingly susceptible to damage from cold temperatures. The amount of damage trees will suffer will depend on the type of tree. Peach and apricots are more prone to damage than apples and pears, mainly because they bloom earlier. When peaches are at the pink stage (flower buds are beginning to turn pink) temperatures of 25 F will kill approximately 10 percent of blooms, while temperatures of 15 F will kill 90 percent of blooms. When peaches are in full bloom, temperatures of 27 F will kill 10 percent of blooms, while a temperature of 24 F will kill 90 percent of blooms. The combination of peaches early blooming and late freezes is the reason peach trees only produce an average of 1 out of 3 years in Central Illinois. While cold temperatures can drastically reduce the amount of fruit your fruit trees produce, you can always look on the bright side – you won’t have to do as much fruit thinning.

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