Autumn: Golden time for Vail Valley trees and gardens |

Autumn: Golden time for Vail Valley trees and gardens

D. Craig Keithley
Vail, CO Colorado

VAIL VALLEY, Colorado –Autumn in Colorado’s Vail Valley is not only a colorful time of the year for trees and gardens, but also the ideal time to prepare trees and gardens for the coming winter.

Autumn growing conditions are ideal. Insects and diseases are inactive and the tree takes full advantage. It’s during autumn that your efforts made on the tree’s behalf have the greatest benefit. Your plants and trees will thrive all the better next spring if they are well cared for now.

The shorter fall days trigger the shedding of leaves, which increases organic matter in the soil, nourishing the root system and fueling the development of new leaf and flower buds. Evergreen trees slough under-producing needles and roots, trying not to carry any excess “baggage” into winter. We can help the trees along with some basic maintenance in these areas.

The autumn window of opportunity is short-lived, so here are some ideas to make sure your trees and gardens are in the best possible shape heading into winter.

Inspect: Take time to thoroughly inspect each tree. Take note of cracks in the trunk, signs of disease or insect damage and the tree’s structural soundness. If you see something unusual call an arborist for a diagnosis and prescription for treatment. A proper inspection can catch small problems now and prevent expensive and dangerous situations later.

Fertilize: As the top of trees are losing their leaves and entering dormancy the opposite is true for the roots. The roots are a place of great activity and require an immense amount of nutrients. The placement of nutrients (fertilizer) into the root zone at this time is highly beneficial. Trees demand an incredible amount of energy as they develop next year’s buds. This energy comes directly from the roots.

Performed properly, deep root fertilization places the nutrients where they’re needed at just the right time. In spring the trees flourish and are more capable of resisting the attacks of insects and disease.

Prune: Insects and disease-causing organisms become inactive in the autumn and no longer pose a threat. The tree can safely be pruned and have time to heal. Removing deadwood while maintaining the trees’ overall structural integrity will reduce risk of future insect and disease infestation, and reduce wind damage.

Thinning should be performed to reduce foliage and growth from the tree’s interior. Less weight on a branch reduces winter damage. Better air circulation within the interior of a tree reduces the possibility of fungal and similar diseases.

If you are pruning for the control of disease be certain to sanitize the tools you are using following each cut. Otherwise, you may spread the disease to uninfected trees.

Mulch: Leaving the top (or all) of a tree’s rootball exposed to the elements can be a recipe for disaster. Tree roots will not tolerate rapid fluctuations in soil temperature. Mulching helps to stabilize the soil temperature, maintain moisture, reduce competition by weeds and assist roots in absorbing nutrients.

The average amount is typically around 3 inches and tends to decompose over time. Avoid the error of allowing mulch to come in contact with the exposed trunk above the rootball. This can suffocate the tree. Finally, choose a high-quality mulch that will offer nutrients as it breaks down over time.

Autumn is the last chance a tree has to get ready for the harsh conditions that winter brings. The more care trees receive now, the healthier they will be come spring.

D. Craig Keithley is the director of plant horticulturist for Land Designs by Ellison and A Cut Above Forestry. He can be reached at 970-453-9154 or E-mail comments about this column to

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