Deb Babcock: Your garden in winter
November 23, 2009
Steamboat Springs — At the annual meeting of the Yampa River Botanic Park, Karen Vail was the featured speaker and discussed the various microclimates we can create in our gardens to accommodate various plants, expanding the range of things you can grow here.
One of the keys to finding the right space for the right plant is to understand where the plant originated. For example, the butterfly bush (Spp. Buddleia) that I purchased in Denver, rated USDA Zone 4 (which is the Steamboat area's zone rating), didn't make it past two seasons in my garden because it didn't get the protection it needed. As Vail said, it isn't "hard-wired" like our native plants to start "hardening off" or become tolerant to our freezing temperatures at the right time. It needed a microclimate similar to its native China, which we can create in our gardens with rocks, walls, trees, structures, and other hard-scape and landscape elements.
Our native plants understand that when our temperatures drop and our daylight hours are shorter here, it's time to start preparing for winter.
This preparation, according to Vail and her source, "Winter: An Ecological Handbook" by James Halfpenny and Roy Douglass Ozanne, appears to be a three-part process.
The first part is that when the plant senses the time is right to start entering dormancy, it moves sugar and nutrients from its foliage into its stems, branches and roots to store through the winter. This is when you notice leaves turning color and eventually falling off most perennials, shrubs and trees. At this point, the plant stops growing.
At this stage, the plant also thickens its cell walls and creates an anti-freeze-like substance within the cell to protect it from damage because of freezing temperatures as low as 14 degrees Fahrenheit.
In the second stage of preparing for winter, the plant creates another chemical or enzyme that keeps the plant from dehydration or drying out because of limited water intake and the fierce, cold winds we experience during the winter. At this stage, the plant can handle temperatures as low as minus 22 degrees.
If temperatures get really cold here, below 22 degrees Fahrenheit, stage-three changes take place, which Vail described as a type of plant cryogenics. This involves the plant forming some type of vitrification or glass formation (with smooth edges rather than sharp edges so as not to destroy plant cells).
Not a lot is known about this stage, which disappears quickly with just a few hours of warmer temperatures.
So if you have native plants in your garden, they know what to do as the weather starts getting colder and colder. If your plants are non-native, they likely need greater protection in terms of a microclimate, covering of mulch or fabric, or even being moved to an indoor shelter for the winter.
Deb Babcock is a Master Gardener through the CSU Extension Routt. Questions? Call 879-0825.