Article and photos by Monika Smith, Master Gardener
With a very nice, long fall in the plus temperatures this year, we’ve all loved being outside and watching the trees change colour.
Only one downside: lack of rain! Calgary experienced the hottest September on record and driest in 140 years! How much moisture is in the ground? The trees and shrubs are slowing down metabolically as you can tell by the leaves turning yellow, orange or even red. It’s gotten colder and the days shorter; when those leaves are all gone, they are dormant but will revive in spring. The ground needs to be moist for winter, not bone dry. Snow is a great insulator for plants, but that’s not a sure thing in Calgary. Chinooks are drying winds.
Although trees are dormant in winter, some keep on photosynthesizing a bit through their bark, for example aspens, which have a fine, greenish bark. Also, some young trees can photosynthesize that way until they mature and their bark is thick and brownish are officially dormant in winter.
Conifers, with their green needles, photosynthesize in winter, but not like flowers or deciduous trees. They must maintain a balance to prevent a ‘system’ overload. Excess light energy from bright sunny days is safely dissipated, protecting the photosynthetic machinery from damage during freezing conditions.
We love our evergreens in winter! And most are native. However, if you’re going to add conifers, native spruce, fir, pine, larches and tamarack cope well with our climate. Easy to grow and hardy are three juniper species: Juniperus horizontalis, Juniperus communis, or Juniperus scopulorum and many cultivars providing creeping, upright or anything in between in size, shape and colours. You will be surprised. Nurseries do have Juniperus sabina, which are originally from Europe and Western and Central Asia, but they don’t do that well in Calgary. Calgary Carpet is a favourite, but from personal experience I won’t get them again as I’ve had a very nice, mature plants just die, turning into a prickly, orange, dead mass; there is no reviving them. Check with local garden nurseries about what is available. And go online to find out what will grow well in your yard. Not all conifers tolerate Calgary.
Non-native conifers such as cedars grow well where winters are cool and wet. That is not Calgary. If you insist on growing one, it may become an expensive annual. If you are determined, plant it in a shady, sheltered spot away from direct sun and winter wind, water well. But be prepared to have your heart broken. There are upright forms of junipers that could be a great substitute. Check those out and be pleasantly surprised.
Why water in the fall? That top up, especially this year, is important. Get water into the ground; it will freeze, stay put, giving a tree or shrub a good start in the spring. Again, our winters are dry and sometimes, not a lot of snow cover. Check out guidelines at Calgary Horticultural Society’s website: calhort.org or the City of Calgary, YardSmart information. Local plant nurseries will also provide great information on how to maintain your trees all year round. We all want you to succeed! Look at native trees and shrubs or their cultivars; you’ll be surprised at the variety and how beautiful and hardy they are.
For more information about Naturally, Glendale, contact: Monika Smith [email protected].
Western larches (Larix lyalli) at Highwood. A beautiful native conifer that turns brilliant gold in the fall then loses its needles. For your garden? Select Larix sibirica as that tree will fit in an urban lot.
Poplars (Populus ssp) and aspens (Populus tremuloides) in Edworthy Park, near the Bow River.
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