If you can figure out how to maneuver through the national political scene that has infected my Facebook page, you can see that almost every one of my local “friends” has taken a photo of the fall foliage in Southwest Colorado.
The striking yellows and occasional oranges of the high-elevation aspens bleed nicely into the autumnal tones of the Gambel oaks at lower elevations.
The color palette has made for multiple comments like, “The photo doesn’t do the beauty justice,” which is then typically followed by one of their friends from the Northeast saying something like, “These colors don’t even compare to what we see here in Vermont!” You can see what comes next, which can closely resemble a comment comparing Donald Trump with the devil or Hillary Clinton as the consummate liar. Then, I get off Facebook.
We seem to be at the peak of the colors this first week in October, and as temperatures start dropping, so will the colors. Environmental conditions – such as temperature, sunlight and soil moisture – can influence the quality of the fall foliage display. Fall colors – yellows, oranges, reds and purples – are revealed when the plant stops producing chlorophyll. As the chlorophyll (green color) disappears, pigments like xanthophyll (yellow), carotenoids (orange) and anthocyanins (reds and purples, which are actually manufactured from sugars trapped in leaf) are seen.
Cool temperatures, particularly at night, coupled with abundant sunlight, promote the formation of more anthocyanins. A hard freeze can destroy the mechanisms for manufacturing anthocyanins, so an early freeze frequently equates to an early end to colorful foliage. If the plant incurs drought stress during the growing season, it can sometimes cause leaves to drop before they have a chance to develop fall coloration.
The “ideal” conditions may be what many areas are seeing this year: a growing season with plenty of moisture followed by a somewhat dry, cool, sunny fall that is marked by warm days and cool but frostless nights. Wind and/or heavy rain may cause the leaves to be lost before they develop their full color potential and make the raking of leaves an earlier event than you wanted.
If you want your own fall color, in your own yard, right now is a fantastic time to plant your own tree or shrub. Soil moisture is adequate, soil temperatures are still relatively warm (very few areas have yet to see temperatures below 30 degrees until this week). and the ground may be easier to work than what we deal with in spring. Local nurseries typically still have plenty of fantastic options and often those trees can be found at excellent prices. But be aware that conifers are more susceptible to winter desiccation since their leaves (needles) continue to lose moisture they hold during the winter. Our cold northern winds can exacerbate this desiccation.
Some ornamental deciduous trees that can have amazing fall color would be: the maples (Rocky Mountain, Wasatch, Amur or Tatarian are great choices), Chanticleer pear, red or white oak and the hawthorns. You can also visit the nurseries (right now!) as the colors will definitely be on display.
Darrin Parmenter is the director and horticulture agent of the La Plata County Extension Office. Reach him at darrin.parmenter@co.laplata.co.us or 382-6464.
