With the daylight trickling away, gardens all across Calgary are winding down their season. However, savvy gardeners know that this time of year is a crucial one to think about the winter health of your garden. That's especially crucial since the unpredictable weather in the city could change at any moment, presenting a unique challenge for Calgary gardeners.
“Winter could come tonight. So we could get cold for a night then warm up again, and the plants can get confused,” said Victor Kallos, with BKDI Architects. It's often not as dire a situation as in spring, where sudden warming, followed by a cold snap can kill off tender new growth, but these fall periods can damage plants just the same.
Mulch to protect plants from cold
One of the easiest ways to protect perennial trees and shrubs is with mulch, placed around the base of the plant to protect it against winter kill. And one of the easiest sources of mulch is something gardeners often view as a nuisance - the plant's own leaves, or leaves from larger deciduous trees. “When the leaves fall, I go over them with a lawnmower so it mulches them. I collect them in a bag and just before the first snow I put them around the perennial beds, and that gives them some protection, some added warmth,” said Kallos. Bark mulch can also be used, but leaf mulch will help provide more nutrients to plants and is easier to remove in spring.
Send evergreens into hibernation well-prepared
Evergreens have their own specific issues, since they continue to lose moisture throughout the winter, and can be especially hard hit by a Chinook. Watering-in these trees and bushes from now until the frost hits is essential to keep them healthy through the colder season and ready for spring, Kallos said. This is a bit of a balancing act, however, since the roots of plants still need oxygen, and too much water can drown them. Keep the soil moist but not soaking.
Don't feed something that's going to sleep
Gardeners may often make the mistake of fertilizing too much in fall, right as the plants are preparing to go into hibernation. “If you fertilize now, it'll encourage it to grow, and the new growth will freeze and damage the plant,” said Kallos.
Give your plants a haircut, but not a buzz cut
Once perennials stop growing for the year is the best time to think about pruning. This encourages new growth in the spring and also keeps plants manageable. The fact that it does encourage growth is exactly why you need to wait until they go to sleep for the year. Cutting away dead wood will removing hiding places for insects that might damage the rest of your plants.
Nothing complicated for lawns
Most grass lawns will take care of themselves over the winter, and just need a little water in fall and a low-nitrogen, slow-release fertilizer that will be there for the grass in spring when it wakes up. Make sure to get rid of those leaves, which could damage grass if they're allowed to sit. Fall may be also a good time to aerate your lawn, with the plugs then decomposing and providing some nutrients for the rest of it.
Dream about next year
The best thing a gardener can do is to take stock of what happened in their garden each year – which plants thrived, and which plants struggled. Most of Calgary is in the 3a hardiness zone, but microclimates exist that mean some plants will prosper where guidelines dictate they shouldn't, and others won't make it where they'd be expected to. “Clean, prepare, and dream about next year. Document what's worked and what hasn't,” said Kallos.