September In The Garden

 Autumn Leaves

Fall is approaching with all its seasonal beauty, cool temperatures and Thanksgiving and Hallowe’en right around the corner. Once more, school and university have begun with fall courses becoming available on every topic we can think of – especially gardening!

The University of Saskatchewan offers affordable gardening workshops, events and online courses in fall and winter.  For more information go to The instructors are horticultural experts with many years of experience gardening in Saskatoon.

September is always a very busy month in the garden. One of the most important things to be aware of is the approximate date of the first light frost of the season. According to the Old Farmer’s Almanac in Saskatoon that date is approximately September 19. Now is the time to keep an eye on the night temperatures and listen to the local weather report.

Harvest Vegetables

At the top of the to-do list for September is to continue harvesting and storing your garden vegetables, bush and tree fruit. Root vegetables such as beets, carrots, parsnips and potatoes can be left for a longer period of time as they are unaffected by cool September temps. Leave harvested onions on top of the soil for about a week or two to ‘cure’. This toughens up the outer skin, helping to avoid disease in storage. Later in the fall, when the vegetable garden has been cleaned up, spread a layer of compost overtop and leave it for the winter.

For those gardeners wondering about planting in fall, I highly recommend it for trees and shrubs during the months of September and October. The soil is still warm and it will be some time before it freezes.


Trees and shrubs will benefit from a handful or two of bone meal mixed into the backfill soil. Apply the required amount of Mykes directly to the rootball. Remember that Mykes is a living fungus that helps new roots venture out into the soil – it is not a fertilizer. Mykes has a ‘best before’ date on the container and should not be allowed to freeze or be left in a high heat environment. Regularly water your new plantings right up to hard freeze up.

As far as perennials are concerned, spring bloomers fair better when planted/moved in fall. Fall blooming perennials fair better when planted or moved in spring. If dividing and transplanting in fall, leave the leaves on the plants until they have died back for the winter. Then prune all the dead plant material back to just above ground level. Of course there are always exceptions to these rules so please check out your plant’s care chart or your favorite Zone 3 gardening book!

Deciduous trees, shrubs and perennials will often lose some or all of their leaves after fall transplant. This does not mean the plant is dead! Below ground, new roots are busy forming in the warm soil, unaffected by the cool air above. Continue to water but check the soil moisture every time you do. You don’t want to drown the plant.

Mixed Fall Planters

Extend your outdoor flowering plant season by creating a few mixed planters to replace some of the tired annual ones.  Annuals that enjoy cool fall temperatures are dusty miller, pansies, violas, mums, snapdragons, alyssum, marigolds, ornamental cabbage and kale, petunias and zinnias.

Indoor and outdoor plants should not be fertilized after August 15. I must admit though, I have lightly fertilized my annual planters after that date if fall is proving to be a warmer than usual. If you feel extra adventurous plant a couple of small garden beds with short days to maturity lettuce varieties, radishes and cilantro. Cilantro grows best in cooler weather and is slow to bolt. For those of you with grow lights continue in late fall and winter to plant greens, herbs, microgreens and start some sprouts.   

Garlic should always be planted in fall. Mulch the planted area with a deep layer of straw as winter approaches. For more information on planting garlic in Zone 3, visit my October In The Garden Blog, September 27, 2021.

Bone Meal

At the end of September into October, plant those spring flowering bulbs that are the first to appear in spring. For new gardeners these bulbs are tulips, daffodils, crocus, fritillaria, snowdrops, allium, and lilies. Choose bulbs that are firm and have few marks on the exterior skin. Be sure to purchase some bone meal to mix into the soil below the bulbs. Bone meal helps to establish good root growth. After planting, water the bulbs once thoroughly and then leave them be until you see them pop up in spring.

There are also lots of fall blooming annuals that can be planted up in containers to create a beautiful mixed show of fall foliage and flowers. These annuals include pansies, violas, dusty miller, chrysanthemums, ornamental cabbage and kale, snapdragons, celosia, coleus, ornamental peppers, dianthus, alyssum, calendula and petunias.

Peonies are a herbaceous perennial that should be planted or divided/transplanted in the fall. It has been proven that fall planted peonies establish themselves faster and flower sooner than those planted in spring. To move a mature peony plant, wait until it has gone dormant. Peony tubers should be planted with the eye or eyes (buds) facing up and no more than two inches below the top soil level. If you plant a peony too deep, it will not flower.


You will probably notice that your lawn perks up during the cool temperatures of fall. September is a great time to over-seed your lawn or lay sod. Repair bare spots with a product such as Scotts EZ Seed Patch and Repair. Toward the end of September into October apply a fall fertilizer available at most garden centres. Fall fertilizers strengthen roots and improve your lawns winter hardiness. Fill and calibrate your fertilizer spreader on a hard surface to avoid accidental spills that can burn a lawn. Always err on the side of applying too little fertilizer, instead of too much. Less is more!

 FYI:   For those of you wondering about when to lift your dahlia tubers and gladioli corms, remember to let the foliage die back first before you lift them and store for the winter.  Watch this space for a Do It Yourself blog on this topic in October!

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