Quick answer: fall is planting season in Ontario, not just cleanup season. Spring bulbs, garlic, trees, and shrubs all go in the ground between September and freeze-up, and perennials divide best while the soil is still warm.
What to Plant in Ontario in the Fall
Four groups thrive from fall planting here. Spring bulbs like tulips and daffodils need the winter cold to bloom at all. Garlic goes in from late September through October and gets a head start no spring planting can match.
Trees and shrubs also establish well in September and early October, while the soil is warm enough for root growth but the summer heat stress is over. And cool-season vegetables like spinach and lettuce squeeze in a final harvest before hard frost.
When to Plant Spring Bulbs in Ontario
Timing beats technique with bulbs. In the GTA that means planting from about mid October to early November, once nights are consistently cool.
“The ideal time to plant bulbs is approximately four to six weeks before the ground freezes, around mid-October to early November.”
Ken Johnson, Horticulture Educator, University of Illinois Extension
Depth follows a simple rule from the same guide: plant each bulb two to three times as deep as it is wide. Point the tip up, firm the soil, and water the bed well so roots can start before freeze-up.
How to Divide and Transplant Perennials in Fall
Fall is the easiest time to divide crowded perennials like hostas, daylilies, and peonies. Lift the clump, split it into fist-sized sections with healthy roots, and replant at the same depth with a good watering.
The same warm-soil window suits moving shrubs or young trees: they re-root now without supporting a full canopy. One job that does NOT belong in fall is major pruning; our fall maintenance guide explains why pruning waits for late winter.
Should You Clean Up Garden Beds in the Fall?
Partly. Remove anything diseased, and clear soft, mushy growth like hosta foliage after frost, which otherwise mats down and shelters slug eggs. Send diseased material out with yard waste, never into the compost.
But do not strip the garden bare. Standing stems and seed heads of coneflowers, black-eyed Susans, and ornamental grasses feed birds and shelter overwintering pollinators, and they add winter structure. Extension programs now recommend leaving healthy stems up until spring.
Lawn work is its own list, from feeding to the last mow, and it lives in our fall outdoor maintenance guide.
How to Store Tender Bulbs Over Winter
Dahlias, cannas, and gladiolus will not survive an Ontario winter in the ground. Wait until the first frost blackens their foliage, then lift the bulbs and tubers carefully with a fork.
Let them dry for a few days in a ventilated spot, brush off loose soil, and store them in peat moss or vermiculite somewhere cool, dark, and frost free. A basement corner at 5 to 10 degrees C is ideal. Check monthly and discard any that turn soft.
How to Prepare Garden Soil for Winter
Feed the soil in fall and it feeds everything next year. Spread 2 to 3 inches of compost over beds and let winter work it in, or dig it into the top layer of vegetable beds now.
“To help the bulbs survive the winter, cover the soil with two to three inches of mulch.”
Kristine Lang, Assistant Professor and Consumer Horticulture Specialist, SDSU Extension
Wood mulch belongs on planting beds; stone belongs on paths and drainage lines. Our river rock vs mulch comparison covers which material goes where, and our soil and mulch range has both.
Fall Planting Calendar for Ontario
Here is the season at a glance for the GTA. Dates shift a week or two with the weather, so let soil and night temperatures make the final call.
| Window | What to plant or do |
|---|---|
| Early September | Divide and move perennials, plant shrubs and trees |
| Late September to October | Plant garlic and cool-season vegetables |
| Mid October to early November | Plant spring bulbs |
| After first frost | Lift and store dahlias, cannas, gladiolus |
| Before freeze-up | Compost beds, mulch 2 to 3 inches, final watering |
Where to Buy Fall Garden Supplies in Mississauga
Sid’s carries bulbs-to-beds fall supplies: soil, compost, and mulch, aggregates for paths and edging, and advice from people who plant in this climate. Visit us at 6000 Ninth Line in Mississauga or contact us with your project list.
Fall Gardening FAQs
When is it too late to plant bulbs?
You can plant until the ground actually freezes, often late November in the GTA. Late-planted bulbs may bloom a little later their first spring, but planted and watered beats stored and forgotten every time. After freeze-up, pot them and chill them instead.
Should I fertilize the garden in the fall?
Feed the soil, not the plants. Compost and slow amendments are ideal now, but skip high-nitrogen fertilizer on shrubs and perennials because it pushes soft growth right before frost. Lawns are the exception and get their main feeding in mid September.
Should hostas be cut back in the fall?
Yes, once frost collapses the leaves. Soft foliage left on the ground mats down, breeds rot, and shelters slug eggs for next year. Cut it to a few inches and compost healthy leaves. Leave sturdy perennials and grasses standing for winter.
Can you plant trees in October in Ontario?
Yes. Roots keep growing until the soil drops near 5 degrees C, so an October-planted tree settles in well. Water deeply every week until freeze-up and finish with a wide mulch ring, kept back from the trunk.
