Hello, which gardening zone is Toronto and which blueberry trees/plants are best for planting/surviving winter in Toronto and when is the best to plant them?
Thank-you for contacting Toronto Master Gardeners (TMG) with your question.
Toronto is considered to be Zone 6 in the Canadian system of hardiness zones, but Zone 5 in the USDA system. This previous TMG answer to a question about Toronto climatic zones clarifies the assignment of zones in Canada and by the USDA.As you research possible plants, you may see either zone system in use depending on your source of information.
Since you mention “trees” you are probably thinking of high-bush blueberries (Vaccinium corymbosum). These are the tallest of the blueberry species. Both low-bush blueberries (V. angustifolium) and half-high blueberries (an interspecies hybrid) are smaller, lower lying shrubs and are hardier plants than the high-bush types. Having said that, Toronto is in one of the warmer zones in Ontario and most of the high-bush varieties are hardy to at least Canadian Zone 5 so you should be able to overwinter your plants successfully here. Keep in mind that hardiness varies depending on the variety. This article on growing blueberries in Ontario home gardens put out by the Ontario government (OMAFRA) suggests that some of the hardiest varieties of high bush blueberries are ‘Northland’, ‘Bluecrop’, and ‘Jersey’. It is important to note that planting at least 3 varieties together is recommended for optimum pollination and largest berry production. A further benefit is an extended growing season since different varieties have different harvest times.
Summer is generally not the best time to plant shrubs. It would be better to wait for the cooler temperatures of early fall. Make sure to plant early enough for root development before the onset of winter. You may already be aware of the importance of planting blueberries in an acidic soil (a pH of 4.5 to 5 is considered to be optimum). Garden centres usually stock soil pH testing kits if you are unsure of your soil chemistry. Most soils in the Toronto area are neutral or slightly alkaline so achieving an acid soil can be a challenge. Many gardeners choose to overcome this by planting their blueberries in containers where they can monitor and adjust the soil pH more easily. Keep in mind if you decide on containers that winter protection will be more important than if planting directly in the garden. A further caution on winter care is to ensure that your shrubs are protected from hungry rabbits!
Halton Master Gardeners have produced a good, brief information sheet on growing both high- and low-bush blueberries in our area .
This article from the University of Wisconsin addresses growing blueberries in containers specifically.
Best of luck with your blueberry patch!