Gardening Zones 101
What are Hardiness Zones and Why do they Matter?
Hardiness zones are a way of categorizing climate patterns across different regions. These zones are determined by the minimum temperatures that a region experiences during the winter months. Each zone represents ten degrees fahrenheit of temperature difference, with each zone also divided into “a” and “b” segments that represent five degrees fahrenheit of temperature difference. Knowing the hardiness zone for your area is important because it can help you select plants that will thrive in your local climate and not be killed by winter weather here in Southwestern Ontario.
Understanding hardiness zones can seem daunting, but it’s actually quite simple! Just like the temperature, the lower the number, the colder it is in that region. The hardiness zone system was developed by the United States Department of Agriculture (USDA) in 1960, with a Canadian version first published in 1967 (the most recent release was 2012). This system divides North America into 11 hardiness zones. Each zone is labeled by a single number with lower numbers representing colder regions (Zone 1 covers northern places like parts of Nunavut), and higher numbers representing warmer regions (sunny Florida has regions that are zone 10).
What Hardiness Zone is London, Ontario?
London, Ontario Canada is located in hardiness zone 6 (both 6a and 6b zones can be found in the city). This means that the average minimum temperature in London during the winter months is between -23.3°C to -20.6°C (or -10°F to -5°F for 6a) and -20.5°C to -17.8°C (or -5°F to 0°F for zone 6b). You can see more information about the hardiness zone of your home at this interactive map: https://www.plantmaps.com/interactive-ontario-plant-zone-hardiness-map.php
If you live in this area and want to grow plants that will survive the winters here, you should look for a plant that has a hardiness zone of 6 or lower. Plants that are native to warmer climates, such as petunias (zone 9 – 11) will look lovely for the summer, but once temperatures below their zone tolerance arrive, they will die.
What Hardiness Zones Should I Buy?
At Heeman’s we prefer to err on the side of caution and suggest you select plants that aren’t just on the edge of our zone but ones that can survive a bit colder. Opting for a Zone 5 or colder plant gives you extra peace of mind that even in an unseasonable cold winter, your plants can survive.
Remember to Consider Microclimates too!
It’s important to note that hardiness zones aren’t the only factor to consider when selecting plants for your garden. Microclimates and variants exist everywhere! Planting something in the middle of an open field on the outskirts of town will mean the plant is more exposed to the elements like drying winter winds, so you should likely choose a plant that is more hardy such as something that is rated for zone 4 or 5. If you live in the middle of the city and are choosing a plant for a sunny courtyard that is blocked by the wind on all sides, the microclimate in that space might allow you to experiment with a plant that is slightly less hardy like a zone 7 (keep in mind those aren’t guaranteed to survive, but they might!).
Overall, understanding hardiness zones is really helpful for all gardeners who want to select plants that will thrive in their local climate. By knowing the hardiness zone for your area, you can make informed decisions about which plants will grow well in your garden. With this knowledge, you can create a beautiful and successful garden that will flourish year after year.
Where do I Find Plant Hardiness Zone Information?
Most plants will have hardiness zone information on the tag that you can reference. Each company may show this information slightly differently. If you notice a range of numbers (like petunias that are zone 9 – 11) that means the coldest zone that it can tolerate is zone 9 and the warmest that it can handle is zone 11. It will struggle to thrive and/or survive in anything outside of those zones.
In the video here, we’re looking at the tag of a beautiful Columbine! You can see the hardiness zones are listed as a zone 5 (coldest this plant can survive) up to a zone 9 (warmest this plant can survive). Because our zone (Zone 6) is between those numbers, this plant should be able to tolerate our winters.
Other Popular Hardiness Zones for Heeman’s Shoppers
To find your exact garden zone, you can use the same resource we did and visit http://planthardiness.gc.ca/
- Dorchester 6a
- Ingersoll 6a
- Thamesford 6a
- Thorndale 6a
- Strathroy 6b
- Stratford 6a
- Exeter 6b
- Lucan 6a
- St. Mary’s 6a
- St. Thomas 6b
- Waterloo 5b
- Toronto 7a
- Brantford 6a
- Chatham 6b
- Belmont 6b
- Toronto 7a
- Bracebridge 5a
We know our guests come from near and far so we wanted to include a few popular regions our gardeners live in so you can see the Hardiness Zone in your area too.
