This week’s forecast is a gift for anyone with trees in the yard. Environment and Climate Change Canada is calling for sunshine most days in Lethbridge, with afternoon highs between 9 and 17 through Sunday. That makes it a good window for one of the most useful fall jobs: a slow, deep watering before the ground freezes.
Why it matters
Alberta Agriculture’s advice on preparing trees and shrubs for winter calls fall watering crucial. The best time is after leafy trees have dropped their leaves and before the ground freezes.
Evergreens like spruce and pine don’t go fully dormant, so they keep using some water all winter. The moisture that freezes around their roots is what they’ll have to draw on until spring, and our winter winds can dry out needles quickly.
How to do it
- Water slowly and deeply around the drip line, the outer edge of the branches where rain drips off, rather than right against the trunk.
- For young trees, water at the root ball.
- A simple trick: poke a few small holes in the bottom of a large pail, fill it, and set it over the roots so the water seeps in slowly. A soaker hose or drip line works too.
- Don’t let the water run off. If it starts pooling or running onto the sidewalk, turn it down or move the hose.
- Water during the mild part of the day so it has time to soak in before the overnight frost.
Finish the job
Spread a ring of mulch 10 to 15 cm deep around the base, shaped like a doughnut so it doesn’t touch the trunk. Mulch holds moisture and helps protect the roots from freezing.
Rake up fallen leaves and dead plants from under your trees and shrubs. Alberta Agriculture notes they can shelter insects and diseases over the winter.
Think ahead to icy sidewalks, too. De-icing salt that runs off into the soil is a major cause of damage to trees and shrubs in Alberta, so go easy on salt near your plants.
When you’re done, disconnect and drain the hose so it doesn’t freeze at the outdoor tap. For more seasonal jobs, see Home and Yard and Water, Plumbing and Drains.