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Frost Damage
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by Diana Roberts |
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Category:
Disease-Pests
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| In order for deciduous trees and shrubs to carry on their normal cycle of winter dormancy and growth in the spring, it is essential to have the cold winter weather. What's not good for deciduous plants is an early spring frost. A severe frost to fruit trees can cause damage to emerging buds and shoots which could result in total or partial crop loss. It is even possible for these frosts to completely kill a tree. |
Cold flow
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| When planting your fruit trees or other frost sensitive plants, you need to take a good look at the surrounding area. Cold air will flow to the lowest point of your property, so any buildings or barriers will block the cold air from moving off your property. Try planting sensitive trees and shrubs in higher areas if possible. Another good idea to prevent frost damage is to buy tolerant varieties of plants. |
Two types
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| We all know what frost is; it is a deposit of ice crystals on the ground or exposed surfaces when the temperature falls below zero degrees. You may not know there are two types of frost. White frost happens when the air is moist and dew forms on the ground before the temperature falls below zero. When the temperature reaches zero, the dew freezes in a white coat of ice crystals. Black frost occurs when dew forms below zero degrees, therefore causing frost which you can’t see. |
Clouds
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| There are ways of predicting when the frost will come if you look for them. Many times you will have frost after a day of clouds or rain that clears off later in the day giving you a clear, still night. If the day is cloudy and there is no sun during the day to heat the soil, what little heat there is, is soon gone and frost will appear if the sky is clear. Lack of wind and a clear sky will cause perfect conditions for frost. Just a small amount of clouds in the night sky will keep frost away. |
Late
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| How badly buds and shoots are damaged by frost depends on how late in the spring it occurs. If your buds are still dormant, the damage is minimal, but once they start to open up, a hard frost can cause a lot of damage. If your plants receive a minor frost, you will see yellowish-white areas on young leaves. These spots will turn brown over time and fall out, which makes the leaves appear distorted or tattered. A severe frost can turn buds and shoots brown and limp within hours. Any developing fruit could develop a blackened heart and fall within a few days when it receives a hard frost. |
Soil
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You can reduce your chance of frost damage by allowing the soil to receive heat from the sun during the day. At night, the radiant heat from the soil will warm the air above it keeping frost damage to a minimum. Keep the soil under shrubs and trees weed-free, moist and compact to maximize the amount of heat it stores during the day. Cultivated soil will have large pockets of air which insulates it and reduces the ability to store heat, so it is best not to cultivate soil during frost periods. Lightly water the soil to help store heat, as moist soil will conduct heat more readily than dry soil. Do not over-water during frost prone periods, as more water will not help store more heat, but it could damage young roots. You need only keep the top couple of inches of soil damp. |
Snow
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The best thing you can do right now to prevent frost damage in the spring is to keep a heavy cover of snow around your trees and shrubs. The snow cover will ensure the plants don’t break dormancy prematurely if the weather warms for a few days in a row. A dense canopy of a tree will protect the lower part of the tree from frost (though the upper area may take some damage).
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Plants
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Some plants are hardier than others, but the least hardy plants or trees are asparagus, beans, berries (except cranberries), cucumbers, lettuce, plums, potatoes, summer squash, tomatoes, begonia, impatiens, lobelia, marigold, salvia and zinnia. Some which are moderately hardy are apples, broccoli, carrots, cauliflower, cranberries, parsley, pears, peas, radishes, spinach, coreopsis, pinks, calendula, and sweet pea.
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Hardy
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Very hardy plants include Beets, Brussels sprouts, cabbage, rutabagas, turnips, cornflower, ornamental cabbage, pansy and primrose. Another way to prevent frost damage is to use a cloth to cover your tender plants. Remay cloth, made for this purpose, will keep the temperature a few degrees warmer than the surrounding air. I have also found that plants stored under a tarp will not be as likely to get frost damage. When I used to bring in a shipment of plants from Chilliwack, I had a large area covered with tarp to put the plants under and they never took a frost. There seemed to be just enough heat in this covered area to allow the plants to get acclimated gradually to our cooler weather.
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