April Frost brings May concerns

Mother’s Day is fast approaching and away should go the chance for frost and freezes in the Grand Valley and other low lying areas of Colorado.  Unfortunately the last weekend of April and three weeks prior we had some late cold temperatures.  Many plants were a good month ahead on growing because our February and March had been so warm.  The first of the frost/freeze wasn’t too bad.  Most of our fruit crop just had a good thinning and some just the lower limbs were affected.  Areas that were lower, like my residence in Fruita, got much colder.  I lost all my peaches and plum fruit for this year and my apples were thinned heavily.  We tend to forget that cold settles.  I had tried covering my smaller trees, but when you get down to 21 degrees F, a cover doesn’t do it.  

The Palisade area was much warmer (29 plus) and with orchard fans running were able to avoid great damage; then came the second frost April 29^th and 30^th.  I didn’t see much more fruit damage; it is dependent on the bud or fruit stage and how cold it gets for several hours or more.  But I did see many large ornamental trees get hit hard by the cold.  They were just at the right point of expansion of the leaves. I have noticed cold damaged foliage on cottonwoods, sycamores, elm, honey-locust and oak.  

Cold damage on a baby Kentucky Coffeetree in our Nursery area- SLC

Even Siberian Elms showed some cold damage- notice the larger leaves on the tips-
New foliage is now emerging- SLC

My potatoes had damage to the edges of the top leaves and we have had some shrub samples come in with cold damage.  I found a good handout for preventing frost damage from Arizona Extension.  https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1002.pdf

SO what do you do if you had cold damage?  Many people at first want to cut off some of the damage or fertilize.  If the tree was in good health, a second set of leaves should emerge.  Give it time.  Patience has its virtue.  Don’t prune until new shoots have emerged; then remove the dead.   And don’t fertilize.  This plant is under stress from the frost damage.  We don’t want to try to force it to grow and cause more stress.  

Susan's potato plant with frost damage

Here is a link to how and when to fertilize: http://planttalk.colostate.edu/topics/trees-shrubs-vines/1720-when-to-fertilize/ Keep the tree watered but don’t overdue.  http://www.ext.colostate.edu/mg/gardennotes/635.pdf With some patience and good basic care, your tree and other damaged plants can come back as long as they had some reserved energy and the temperature didn’t get too cold for the particular plant.  So now that we have gotten the freezing temperatures out of the way, it’s time to plant our tomatoes in Grand Junction and wish mom Happy Mothers Day!

Plant Select plant: Scutellaria resinosa 'Smoky Hills'
Didn't see any cold damage on it.
Happy Mother's Day

By Susan L Carter, Horticulture Agent, CSU Extension, Tri River Area