It's hard to say goodbye to summer, especially in Calgary where we get such a short amount of it, but there is no denying that fall is upon us. Now is a good time to do a bit of work around the yard to put it to bed cozy for the winter.
It's a great time to fertilize your lawn with a winterizing fertilizer with a moderate level of nitrogen and high in potassium (the last of the 3 numbers). The grass should be left a little longer for the winter, think of it as the warm blanket for the roots below, and raise the mower blades to about 7-9 cm. Rake up fallen leaves or mulch with a mulching mower and leave them in place. If there is a large layer of thatch, it may be a good idea to aerate or dethatch the lawn. It's also a great time to put down some grass seed. Even if it doesn't sprout before the snow flies, it will be laying in wait for springtime!
Now is also the time to plant bulbs such as crocuses, tulips, and daffodils. Plant them with the tip pointing up in well drained soil. Generally they should be positioned 3 times deeper than their height. Note that squirrels may be prone to digging up and eating freshly planted bulbs and deer are fond of them in the spring; since both these critters are common to the Calgary area, you may want to do some additional critter-proofing.
To deter critters from using your materials as their winter nests, wait until the ground is frozen to cover tender perennials with mulch or compost. Cut out blackened stems and foliage as it dies from overnight frost. Also remove any diseased foliage as this will weaken the entire plant, and trash it, do not compost! Attractive seed pods can be left for winter interest as well as to attract birds.
Early fall is a good time to plant new trees, but once the ground freezes it can be hard to deliver the amount of water a new tree needs. It may also be getting hard to find strong trees from the nursery as they try to clear their stock in the later part of the summer and early fall. Try to avoid pruning trees in the fall unless absolutely necessary as cuts seem slower to heal and it is such a prevalent time for mildew and fungi.