Fall Gardening Tasks for Southern Ontario: A Complete Guide

As the vibrant colors of fall sweep across Southern Ontario, gardeners have a prime opportunity to prepare their landscapes for the winter ahead while setting the stage for a flourishing garden next spring. Fall is a critical time for tasks like soil conditioning, pruning, planting, and cleanup, and tackling these chores ensures your garden stays resilient and beautiful year-round.

Here’s a detailed guide to fall gardening tasks that Southern Ontario gardeners can follow to ensure optimal garden health and beauty throughout the changing seasons.

1. Clean Up Garden Beds

Fall is the ideal time to tidy up garden beds by removing dead plants, fallen leaves, and other debris. Clearing out organic material helps to:

Prevent pest infestations: Many insects lay eggs in fallen leaves or plant debris, which can carry over to the next growing season.
Reduce fungal diseases: Removing diseased plant parts reduces the risk of diseases such as powdery mildew from overwintering in your garden.
Improve airflow: Clean garden beds improve airflow around plants, reducing the risk of mold and mildew.

Pro Tip: Instead of disposing of all garden waste, use healthy plant material to create a compost pile that will be ready for use next spring.

2. Add Mulch for Winter Protection

Mulching is essential to protect your garden through Southern Ontario’s often unpredictable winters. A fresh layer of organic mulch helps insulate the soil, regulate temperature, and prevent frost heave (when soil is pushed up and disturbed by freeze-thaw cycles). Spread a 2-3 inch layer of organic mulch, such as straw, shredded leaves, or bark, around the base of perennials and shrubs.

3. Prune Trees and Shrubs

Pruning promotes healthy growth and improves the shape of trees and shrubs. In Southern Ontario, the timing of pruning can depend on the specific plant species:

Deciduous Trees and Shrubs: Prune after leaves have fallen and trees enter dormancy, usually in late fall. Avoid pruning during early fall, as pruning cuts may encourage new growth that won’t have time to harden before winter.
Spring-Flowering Shrubs: Avoid pruning shrubs like lilacs and forsythia in fall, as they form their flower buds in late summer. If you prune now, you’ll be removing next spring’s blooms.

Pro Tip: Use sharp, clean tools to avoid tearing branches and spreading disease.

4. Plant Fall Bulbs for Spring Blooms

Fall is the time to plant bulbs in Southern Ontario for a stunning spring display. Tulips, daffodils, crocuses, and hyacinths are popular choices that thrive in Southern Ontario’s climate. Here are a few tips for planting fall bulbs:

Timing: Plant bulbs when soil temperatures are around 10°C, usually from mid-September to late October.
Planting Depth: Follow the rule of planting bulbs at a depth three times their height. For example, if a bulb is 2 inches tall, plant it 6 inches deep.
Spacing: Space bulbs a few inches apart to allow for growth and air circulation.

5. Prepare and Condition the Soil

Fall soil preparation sets a strong foundation for spring planting. Southern Ontario gardeners benefit from incorporating organic matter in the fall, giving it time to break down and enrich the soil over winter.

Compost: Spread a layer of compost over your garden beds, about 1-2 inches thick. This organic matter will decompose over winter and improve soil fertility.
Leaf Mulch: Shredded leaves are rich in nutrients and make excellent mulch or can be mixed directly into the soil to improve structure and water retention.
Cover Crops: Planting cover crops like winter rye can protect the soil from erosion and add nutrients. In the spring, these crops can be tilled back into the soil to provide a natural fertilizer boost.

6. Divide Perennials

Dividing perennials like hostas, daylilies, and sedum in fall gives them a chance to establish roots before winter, leading to healthier and more robust growth in spring. Dividing perennials also helps to control plant size and spread, prevents overcrowding, and promotes vigorous flowering.

Timing: Divide perennials early in the fall, giving them enough time to settle in before the ground freezes.
Method: Dig up the entire plant, gently separate the roots, and replant sections about 12-18 inches apart.

Pro Tip: Water newly divided perennials thoroughly and add a layer of mulch to retain moisture.

7. Harvest Late-Season Crops and Store Them

If you have a vegetable garden, fall is the last call to harvest cold-tolerant crops like kale, carrots, and brussel sprouts. Many root vegetables can be left in the ground until the first hard frost, as the colder weather often enhances their flavor.

Storage: Harvested vegetables like carrots, potatoes, and squash can be stored in a cool, dark place to extend their shelf life.
Overwintering: Hardy vegetables such as garlic and onions can be planted in the fall for an early summer harvest.

8. Watering and Winterizing

Although Southern Ontario experiences ample rainfall in fall, it’s essential to ensure that plants are well-hydrated before winter, particularly evergreens and newly planted perennials.

Watering Schedule: Give plants a deep watering before the ground freezes to help them retain moisture.
Drain Irrigation Systems: Drain hoses and irrigation systems to prevent freezing and damage.

Pro Tip: Store garden hoses indoors and insulate outdoor taps to avoid burst pipes during winter.

9. Protect Tender Plants and Shrubs

Certain plants in Southern Ontario, such as roses and hydrangeas, benefit from additional protection against cold temperatures and harsh winds.

Burlap Wrap: Wrap sensitive shrubs in burlap to shield them from strong winds and extreme cold.
Mound Soil: For grafted plants like roses, mound soil around the base of the plant to protect the graft from freezing.
Use Anti-Desiccant Sprays: Apply anti-desiccant sprays to evergreen shrubs to prevent moisture loss and keep foliage from browning.

10. Maintain Garden Tools and Equipment

As the gardening season winds down, it’s a great time to clean and sharpen garden tools, ensuring they’re in excellent shape for spring. Well-maintained tools are more effective and safer to use.

Cleaning: Remove soil and rust from tools. Use a wire brush or sandpaper for stubborn rust spots.
Sharpening: Sharpen pruners, shears, and shovels to make garden tasks easier and more efficient.
Storage: Store tools in a dry, organized space, ideally hanging to prevent rust and damage.

11. Prepare Lawn for Winter

A healthy lawn in fall can make a big difference come spring. Southern Ontario’s cooler fall weather provides the perfect conditions for lawn maintenance tasks:

Aerate: Aerating relieves soil compaction, improves drainage, and allows nutrients to penetrate the root zone.
Fertilize: Apply a fall-specific fertilizer to strengthen grass roots. Look for formulas with a higher potassium content to help grass withstand winter stresses.
Rake Leaves: Avoid leaving a thick layer of leaves on the lawn, as it can smother grass and create an environment for mold.

By following these fall gardening tasks, gardeners in Southern Ontario can not only keep their outdoor spaces looking neat and tidy, but also set the foundation for a healthier and more vibrant garden next spring. Embrace the season’s cooler temperatures and brilliant colors, and take pride in creating a resilient landscape that can thrive in Southern Ontario’s unique climate.