Extension Connection: Avoid winter burn
Winter weather can cause serious damage to plants in our landscapes. This is not so much from the cold but the result of dehydration. Even during the winter trees and shrubs give off moisture through pores in their stems, leaves and needles. This loss of moisture is one reason why many trees and shrubs drop their leaves in the fall. This greatly reduces the water required to keep these plant alive through the winter. Other plants hang onto their leaves in the winter. While some conifers drop their leaves (needles) like the Bald Cypress and Dawn Redwood, the other conifers we have in the Mesa County Arboretum, and you have in your landscapes, retain up to 12 years worth of needles during the winter. These needles need moisture during the winter or they suffer from “winter burn” (e.g. dehydration).
The cold weather we have had thus far this winter will be a good indication of what trees and shrubs are capable of withstanding. While we won’t be able to evaluate trees and shrub loss until spring, I’ll be curious to see how the plants in the Mesa County Arboretum suffered. My guess is all of those plants will come through the winter in great condition.
During the winter of 2008-2009 our Giant Sequoia dropped all its needles but quickly grew a new crop the following spring. It is not uncommon for this tree to respond this way for the first couple of years after transplanting. With several large Giant Sequoias in the Redlands area we already knew this tree did well in this area well before we planted it at the Arboretum. The trees, shrubs and perennials we planted this fall were well-watered upon planting and watered again shortly before the snow storm of December 7. We are quite sure those plants will make it through. To give these plants even more of a chance for survival we will be checking the moisture content of the soil as soon as the snow is melted.
It appears moisture from the snow is sinking into the ground but I want to make sure the moisture has penetrated to a depth of at least nine inches. In the areas I have examined, the soil under the snow has not yet frozen but that will change shortly after the snow is gone. Checking the moisture content before the ground is frozen is my top priority for the Arboretum this month.
Some of our new plants, particularly our new collection of purple-cone flowers (most are not purple) are on a south-facing slope. I checked them on Monday and found the snow immediately around these plants was gone. When probing with my fingers I discovered the native soil was moist but the root ball was dry. This is a common problem with new plants as native soil frequently pulls moisture out of the root ball. By the time you read this column we will have already watered each of those Echinacea with a bucket of water to help them make it through the winter.
The Arboretum is on irrigation water but that does not mean we can’t haul water when it is needed. When I remind people of the need for winter water, even after a snow, some tend to dismiss the idea. After all, won’t Mother Nature take care of her children? The answer to that is yes but only if Mother Nature planted that tree, shrub or flower in the right place. In this area Mother Nature planted very few of the vast collection of plants we have add to our landscapes.
Mother Nature planted the cone-flowers in moist to dry prairies and open wooded areas of eastern and central North America. She planted the Giant Sequoia on the western slopes of the Sierra Nevada Mountains of California and the Dawn Redwood in the Sichuan-Hubei region of China. Even the cottonwoods of which we have several different cultivars in the Arboretum are not native to this area. Our Eastern Cottonwood cultivars are native to riparian (wet) areas of the Eastern U.S. and southern Canada. Our Fremont Cottonwood cultivars are native along flood plains of rivers and along washes and irrigation canals. Even our Narrowleaf Cottonwood and willows are best suited along water courses and around seeps and springs. We moved these plants from their native habitats to meet our needs. Mother Nature had nothing to do with our decision to move ‘her’ plants from where they do well to a less desirable environment.
If we depended on Mother Nature to take care of our landscape trees, shrubs, vines, flowers and turf we would have little to admire. While I love the sparsely vegetated areas between Whitewater and Montrose, that is not what I want people to see at the Mesa County Arboretum or the other gardens around the Mesa County Extension office. While many of the plants you have in your landscape will do ok without much additional care during the winter, if you have plants that struggled this summer or were planted this fall, get out and check the moisture content of the soil and drench them with water if the soil is dry. Like the cats or dogs you adopt, the trees, shrubs, flowers and other plants in your landscape also need care. Give them the care the need and they will reward you with the grace and beauty you enjoy. Neglect them and you might lose a quite but beautiful friend.