When I moved to Colorado three decades ago I expected to be knee-deep in snow and cold to the bone for months on end. Little did I know, Denver winters have long dry stretches, moderate daytime temperatures and bright sunshine that melts snow before it needs to be shoveled. So much easier than the New Jersey winters of my youth. The downside is that plants often suffer from lack of moisture. This year I’m being especially diligent about winter watering to help newly planted trees, shrubs and perennials make it through their first winter and thrive in the future. Whether nurturing young plants or insuring the longevity of established ones, here are Colorado State University’s recommendations for cold season landscape care.
- From November to March, give plants a good drink when four weeks elapse without snow cover or adequate moisture. March is the metro area’s snowiest month (11″); January (7″) and February (6″) average the least.
- Water when temperatures are above 40° and early enough in the day for the moisture to soak into the ground before temperatures dip below freezing.
- Reflective heat from buildings, the lower angle of the sun and areas prone to intense wind cause root systems to dry out more quickly, watch plants in these areas closely and water accordingly.
- Newly planted trees establish slowly – one year for every inch of trunk diameter, (measure 6″ above the soil ). A good rule of thumb is to apply 10 gallons of water per inch of trunk diameter each time you water. Water around the tree, out to the drip line and beyond. The goal is to send moisture to the tree’s entire root system at a depth of 12″. I’ve found running a sprinkler for 30 minutes does the job nicely.
- Newly planted shrubs require more moisture than established ones (over one year old). A first year, 3′ tall shrub requires 5 gallons per watering.
- Mulch is a plant’s friend – it helps maintain moisture and mitigate the damaging thaw/frost cycle.
- Newly seeded lawns and perennials (especially fall planted ones) will benefit from supplemental watering if precipitation is low, too.
According to globalwarmingdenver.com, we’ve received just .02″ moisture in the last two weeks and are about 2.5″ below average precipitation year-to-date. Given our dry days and spring-like temperatures, it’s about time to unwind the hoses.
For more information:
Planttalk Colorado: Fall & Winter Watering
Colorado State University: Fall & Winter Watering Fact Sheet 7.211
Photo credit: Pixabay.com, a source for royalty free images
Written by: Linda McDonnell, a Denver County Master Gardener