Spring is the season of renewal. We patiently expect our plants to shrug off the grays and browns of winter and burst forth in their magnificent splendor.

For some plants, the wait will be longer this spring, and for other plants the renewal will not come.

To determine why we are having such problems, we have to check the weather.

Winter kill is a broad, inclusive description of plants dying from exposure to cold temperatures. With plants, there are two factors that affect winter survival.

Every plant has a minimum temperature it will tolerate. For example, blossoms on my apricot tree only tolerate a temperature of 28 degrees F when they are in full bloom. By contrast, my fully dormant McIntosh apple tree could tolerate a temperature of -50 degrees F without damage.

As long as temperatures do not reach the critical minimum level, the plants can survive. When temperatures drop below those levels, various kinds of plant tissues are damaged. Sometimes the flower buds are killed.

The plant can survive, but it will not flower or fruit. In our area, peach blossoms are sometimes killed in midwinter, as are hydrangea, magnolia and other blossoms.

For other plants, it is how fast the temperature might drop.

The weather summaries for November of 2010 from the Utah Climate Center was, "A warm, dry southwesterly flow prevailed over Utah the 18th and 19th bringing gusty southerly surface winds. High and low temperatures throughout northern Utah were well above seasonal averages.

"... the Thanksgiving holiday (24th through the 27th) brought bitter cold (weather), record to near record low maximum and minimum temperatures.

The Salt Lake City International Airport set a record low maximum temperature of 19 degrees, surpassing its old record of 24 set back in 1931.Well-below normal to record low minimum and maximum temperatures occurred on the 29th and 30th."

This sudden temperature drop after what had been an unseasonably warm fall is what damaged thousands of plant this year.

The warm temperatures prevented plants from preparing for winter, and that led to a myriad problems.

What many people noted was that many trees did not drop their leaves last fall. Leaf drop is an active process, so when the leaves froze, they did not form an abscission layer and the leaves did not drop off.

Most have finally blown off, so that part was temporary. Unless the wood was killed, the plants will recover without problems.

Another kind of winter damage is from desiccation. Many broad-leaved evergreens, including euonymus, photinia, boxwood and laurels have had their leaves turn brown and die as the temperatures got very cold and they dried out and died.

Among the most noticeable problems this year, are the browning needles on sequoias, blue atlas or deodora cedars and some pines. The sudden drop in temperatures last fall created brown needles on many evergreen trees.

Patience is the key for both the broad-leaved shrubs and the trees with evergreen needles. There is nothing you can do now but wait patiently.

If the branches are still flexible, there is a chance they will recover.

The brown leaves on the broad-leaved shrubs will not recover, but if the stems are still alive, the new leaves coming out will push off the brown leaves. Wait and see if the twigs have died and then prune them back as necessary.

For the trees, just wait. If the damage is not too severe, the needles might turn green again. Otherwise, watch and see if the plant sends out new, normal growth this spring.

Another hard-hit group of plants are the roses. In my garden, the stems that would normally be green 18 to 24 inches high are now brown down to ground level or only up a couple of inches.

Since the brown wood is dead, it has to be removed. Hopefully there is enough healthy tissue to allow the plant to grow back and bloom well this summer.

Look carefully for the graft union because if the only sprouts that grow are coming below the graft union, your rose will be the rootstock. That means it will produce a single, off-color red flower that only blooms once.

Although the winter has not been kind, hopefully your plants will not be the victims of the infamous Thanksgiving freeze of 2010.

No one wants to lose their favorite plants to the insidious problem of winter kill but there are no miraculous cures for winter kill.

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Garden tips and events

The Utah Orchid Society is holding its 2011 Spring Orchid Show on April 2, 9 a.m.-7:30 p.m., and April 3, 9 a.m.-5 p.m. at Red Butte Gardens, 300 Wakara Way.

On display, you will find many beautiful, unique orchids. UOS members will be available to answer your questions and there will be presentations on the culture and care of Orchids. Cost is included with regular Red Butte Garden admission. Members are admitted for free. Fore more information, log on to www.redbuttegarden.org.

Larry A. Sagers is a horticulture specialist for the Utah State University Extension Service at Thanksgiving Point.

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