If you think the gardening year ends when the last tomato comes off the vine, I have good news. In Ontario, fall is one of the best times to plant, and for some plants it beats spring. The soil is still warm, the air is cool, the rain is more reliable, and the weeds have mostly given up for the year.
So the honest answer to “can you plant anything in the fall in Ontario?” is yes, but not just anything. Some plants love an autumn start, and a few will simply die. This guide covers what to plant, when to do it in different parts of the province, and what to leave until spring.
The Quick Answer
You can plant these in fall in Ontario:
- Garlic (and shallots)
- Spring-flowering bulbs like tulips, daffodils and crocus
- Trees and shrubs
- Perennials
- Grass seed, for new lawns and overseeding
- Cold-hardy vegetables like spinach and hardy greens (in the right window)
- Cover crops like fall rye
- Native and hardy wildflower seed, sown late so it stays dormant until spring
You shouldn’t plant tender annuals, tomatoes, peppers, basil or anything else that can’t take frost. Those wait for spring.
Why Fall Planting Works So Well
Think about what a new plant needs: roots. Fall gives them the perfect setup for building them.
The soil holds summer’s heat long after the air cools down. Roots keep growing in warm soil, while the cool air means the leaves and stems aren’t stressed and thirsty. Fall usually brings more rain too, so you spend less time dragging a hose around. And there’s far less weed competition than in spring.
The payoff comes next year. A shrub, tree or perennial planted in fall has spent months building roots before it ever has to support leaves and flowers. In spring it takes off, instead of struggling to catch up in the first hot week of June. Bulbs and garlic also need the winter cold to flower or form proper bulbs, so fall planting isn’t optional for them.
Timing: Frost Dates and the “Six Weeks” Rule
Ontario is a big province, and fall arrives at very different times depending on where you live. Hardiness zones run from about 2 in the far north to 7 in the south. Rough averages for the first fall frost run from around early September in Thunder Bay to mid-October in Windsor. Toronto sources vary, with dates anywhere from mid-October to early November. Frost dates are estimates, not promises, and microclimates matter (a downtown yard stays warmer than a rural field).
Two rules of thumb are more useful than any date on a calendar:
- Plant perennials, shrubs, trees and vines up to about six weeks before the ground freezes solid. That gives roots time to settle in.
- For bulbs, watch soil temperature. Wait until it drops below about 15°C (60°F) so the bulb focuses on roots instead of pushing up leaves.
If you’re reading this in late September, you’re still in good shape in most of southern Ontario. If you’re farther north, move quickly, because your window is closing.
A Quick Fall Planting Calendar for Southern Ontario
| What | Best window | Notes |
|---|---|---|
| Grass seed | Late August to end of September | Earlier is better. Seed as soon as you can. |
| Trees, shrubs, perennials | September to mid-October | Water until the ground freezes. |
| Cover crops | September to early October | Fall rye is the classic choice. |
| Spring bulbs | Late September to November | While the ground is workable and soil is cool. |
| Garlic | October | Roughly 4 to 6 weeks before the ground freezes. |
| Hardy greens | Now to early October (in the south) | Best with a cold frame or row cover. |
| Wildflower seed (dormant seeding) | Late October to November | After the ground has cooled. |
Shift everything earlier in northern Ontario and a little later around Windsor and Niagara.
What to Plant in Fall in Ontario
1. Garlic
Garlic is the fall crop. Cloves planted in October grow roots before winter, sit dormant under the snow, and take off in spring for a summer harvest. The cold period is what triggers hardneck garlic to form a proper bulb.
Timing is the main thing. Aim to plant about four to six weeks before the ground freezes. For most of southern Ontario, that means October, and lots of gardeners use Thanksgiving weekend as their reminder. Farther north, plant in late September or early October. A little later still works if the soil isn’t frozen, but yields drop.
How to do it:
- Buy local seed garlic from a farmer or garden centre rather than grocery-store bulbs.
- Break the bulb into cloves just before planting.
- Plant each clove pointed end up, about 2 inches deep and 6 inches apart, in loose, well-drained soil with compost worked in.
- Once the ground starts to cool and freeze, cover the bed with 2 to 4 inches of straw or shredded leaves. Don’t mulch too early, or the mulch can rot the cloves.
2. Spring-Flowering Bulbs
Tulips, daffodils, crocus, hyacinths, alliums and other spring bulbs all go in during fall. They need a stretch of cold to reset their internal clock, and several weeks of root growth before the ground freezes.
Plant when the soil has cooled below about 15°C (60°F). For most of Ontario, that’s late September through October, and you can keep going into November as long as the soil isn’t frozen. Plant too early and the bulbs may send up green shoots that get nipped by winter. Plant too late and the roots don’t have time to form.
A good rule of thumb is to plant about three times as deep as the bulb is tall, which works out to roughly 6 inches for tulips and daffodils. Point the pointy end up, add a little compost, and water in.
Squirrels and chipmunks: they dig up tulips. Cover the planted area with chicken wire before you add mulch, or lay a layer of shredded leaves on top to cover the scent. Daffodils, alliums and fritillaria are naturally left alone by most critters, so they’re a smart choice if squirrels are a problem.
3. Trees and Shrubs
Fall is prime time for planting trees and shrubs in Ontario. The roots get a long, calm stretch to establish before they have to feed a full canopy.
Most nurseries and garden centres also discount plants in September and October, which is a nice bonus. Plant as early in fall as you can, ideally with a full six weeks before the ground freezes.
Tips for success:
- Dig the hole twice as wide as the root ball but no deeper.
- Keep the root flare at ground level.
- Water deeply after planting, and keep watering through fall until the ground freezes. Dry roots going into winter are one of the top reasons fall plantings fail.
- Add a 2 to 3 inch layer of mulch, keeping it off the trunk.
- Skip heavy fertilizer. Late nitrogen encourages tender new growth that winter will kill.
A few fussier tree species are said to do better with spring planting. If you’re unsure about a particular one, ask the nursery.
4. Perennials
Perennials planted in fall get the same head start as trees and shrubs. September and early October are the sweet spot in most of the province. You can also divide and move overcrowded perennials now, a job that’s easier and less stressful on the plant than doing it in the heat of summer.
Set plants in the ground at the same depth they were growing in their pots, water well, and mulch after the first hard frost. Late-planted perennials are more prone to “frost heave,” where freeze and thaw cycles push shallow roots out of the ground. A layer of mulch, and a quick check in early spring to press any lifted plants back down, takes care of that.
5. Grass Seed and Overseeding
Fall is the best time of year to seed a lawn in Ontario. Warm soil germinates seed fast, cool air is gentle on seedlings, rain is more dependable, and weeds are on their way out.
The prime window is late August through September. Each week you wait costs you, because grass seedlings need time to mature before winter, so if you haven’t done this yet, don’t put it off.
- Mow short, rake out debris, and loosen the surface (core aeration helps if the soil is compacted).
- Spread seed evenly, and use a starter fertilizer if you like.
- Keep the seedbed consistently moist for the first couple of weeks.
6. Cold-Hardy Vegetables
Your tomatoes are done, but your vegetable garden isn’t. A few crops keep going into fall, and some handle frost like champions.
- Spinach, lettuce and other hardy greens: they tolerate light frost, and a cold frame or row cover can stretch the harvest well into cold weather. Some gardeners sow spinach in fall to overwinter for very early spring picking. Results vary with winter conditions.
- Radishes and arugula: quick crops that can still fit if you’re early enough in the season and in southern Ontario.
- Garlic, shallots and multiplier onions: the true fall vegetables, planted in October.
Frost-hardy crops usually aren’t damaged until temperatures fall to about -2°C, which is often around two weeks later than the first 0°C frost. If you plant late, protect the seedlings with row cover.
7. Cover Crops
If you’ve got empty vegetable beds, plant a cover crop. Fall rye is the go-to in Ontario because it germinates in cool weather and keeps growing when other plants have quit. It protects bare soil from winter erosion, suppresses weeds and adds organic matter when you turn it under in spring. Sow it in September to early October and rake it in lightly.
8. Native and Hardy Wildflower Seeds (Dormant Seeding)
Many native wildflowers and hardy perennials need a cold, damp period before they’ll germinate. That’s why nature drops their seeds in fall. You can copy the process with dormant seeding: scatter seed in late fall, after the soil has cooled and weeds have stopped growing, and let winter do the work.
Wait until the ground is cold so the seeds don’t sprout and get killed by frost. Choose plants that are native to your area, and check the species names on any seed packet. Cheap “wildflower mixes” sometimes contain invasive plants, like oxeye daisy, that you don’t want.
9. Fall Annuals and Containers
Not everything colourful is a summer flower. Pansies, violas, ornamental kale and mums all tolerate cool weather, so they’re great for filling porch pots and front beds as the summer annuals fade. Mums sold in fall are often treated as seasonal decor. Planted in the ground early enough, some will come back, but don’t count on it.
What Not to Plant in Fall
- Tender annuals and vegetables such as tomatoes, peppers, basil, cucumbers and zinnias
- Tropical or tender perennials that can’t handle Ontario winters
- Anything planted after the ground freezes, because roots can’t establish
- Seeds that will sprout before winter and be killed, such as most warm-season vegetable seeds
Fall Planting Care Checklist
- Water new trees, shrubs and perennials regularly until the ground freezes. Don’t stop just because the leaves have fallen.
- Mulch after planting (and again after the first hard frost for perennials).
- Skip heavy nitrogen fertilizer this late in the season.
- Label everything so you don’t forget what you planted where, especially bulbs.
- Protect bulbs from squirrels with chicken wire.
- Check for heaving in early spring and press any lifted plants back into the soil.
Quick Answers
Is it too late to plant in October in Ontario? Not for garlic and bulbs, which do best in October. Trees, shrubs and perennials can still go in through early to mid-October in the south, provided the ground isn’t frozen.
Can I plant in November? Bulbs, yes, as long as the ground can be worked. Garlic too, though yields drop. It’s too late for most trees, shrubs and perennials.
Is fall or spring better for planting trees in Ontario? Fall is great for most trees and shrubs, because the roots get time to establish. Spring works well too. The key is watering thoroughly in either season.
Can I plant perennials in fall in Ontario? Yes. September and early October is the ideal time.
Does northern Ontario have a fall planting window? It does, but it’s shorter and earlier. Plan on late August to late September for most things, and check your local frost date.
Final Thoughts
Fall is easy to overlook, because the garden is winding down and the days are getting shorter. But it’s a season of opportunity. A few hours with a trowel now gets you garlic next summer, tulips next April, and shrubs and perennials that hit the ground running.
So grab some bulbs, pick up a shrub on sale, and get a few cloves of garlic in the ground. Your spring self will thank you.
What are you planting this fall? Tell me in the comments, and tell me where in Ontario you’re gardening so I can help with timing.
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