"Cuttings" is your source for garden updates and horticultural tips from Reeves-Reed Arboretum's horticulture staff. Check back monthly to find out what's blooming at the Arboretum, get the inside scoop on upcoming events, and learn some timely tips you can put to use in your own garden.
Now that winter is officially upon us, the garden has seen yet another seasonal transformation. A blanket of snow really shows off the bones of the garden – lines and curves are more defined, leafless trees and shrubs are outlined and stand in monochromatic contrast to the winter white. As one of our Board members said while looking out the sun porch window onto the Azalea Garden, "This is why good garden design is so important!"
Snow is actually a great insulator for dormant winter plants and, as it melts, the water percolates through the soil to keep plants and shrubs hydrated. Why, then, do some plants and lawn edges die back in the spring? The culprit could be salt.
As for us humans, excess salt is bad for a plant's diet. Salty soil prevents plants from taking up water and nutrients and is often the real cause of 'winter-killed' grass in the spring, not the freezing cold temps. Sodium chloride, common rock salt, is often used at this time of year as a de-icing agent. It's cheap, readily available in large quantities, and easy to use. The problem is that salt water will still freeze at 0 °F so if temps drop below that, it's ineffective as a melting agent. It also has a strong tendency to cause corrosion, rusting in the undercarriage of most vehicles, and rebar in concrete bridges. Imagine what it does to plants! To be on the safe side, avoid using products in the garden that contain sodium chloride, which is indicated on the package by the letters NACL.
Common alternatives to rock salt are calcium chloride, which is a salt of calcium and chlorine, and magnesium chloride, a naturally occurring material made by extracting the hydrated version from Great Salt Lake brine. These compounds not only depress the freezing point of water to a much lower temperature, they also produce a chemical reaction that produces heat and melts the ice at much lower temperatures. These products are somewhat safer for concrete sidewalks, pets and plants. Even so, they should be used sparingly.
Tips for plant safety when de-icing
Several university and cooperative extension websites offer information on the effects of different de-icing products. Compiling a list of recommended practices from many results in a wealth of tips for keeping the paths and walkways at your home clear and safe while also protecting your plants:
As always, you want to ensure that your garden is healthy while keeping your family, your pets, and your guests safe.
If you love working outdoors in beautifully brisk winter weather, we'd love to have your help at our upcoming January volunteer days! Please join us for a morning of winter work on:
Saturday, January 11: Saturday Volunteers – 9:00 am to 12:00 pm
Monday, January 20: Martin Luther King, Jr. Day of Service – 9:00 am to 12:00 pm
To sign up, or to learn about other volunteer opportunities at the Arboretum, please contact Lisa Martin at firstname.lastname@example.org.