Ontario’s Grape Growing Stages of the Year

Blue grapes on a vine | Wineblots blog

So you have a general idea that vines chill out during the winter, start to grow in the spring, grow rapidly during the summer, and harvest is sometime in the fall. What processes do we see in each stage of the grape’s growth? We’ve put together a quick guide of Ontario’s grape growing season that will make you the hit of your next dinner party.

April – Early May

This is when we begin to tie canes (the stock of the grape) to trellis systems (the support structures used to manage grape vines) to support the vines and position the canopy for a great growing season. It is an important time to cultivate soil for adequate distribution of nutrients and to cover up post-winter pruning and bits of dead or discarded vines.

May – June

As a general rule Ontario’s bud-break (when vines begin to grow) occurs in mid-May, unlike our neighbours in the south who have been seeing bud break for a few weeks now:


We continue to watch the soil, control weeds, and remove anything funky throughout May and into June. In mid-to-late-June flowering occurs. Once the flowering stage begins it’s like groundhog day for the wine industry: there are about 100 days until the grapes are ripe enough to harvest and harvest begins! These first few months of the growing season are incredibly important and growth is rapid.


In July we see continue trimming (the process of cutting off unwanted pieces of vegetation) to shorten shoot length and open the canopy so that it thrives by getting added air circulation and sunlight. As an added note, there are lots of fun wine events to participate in throughout the summer, including Niagara-on-the-Lake’s SupperMarket.

August – September

In August we truly begin to see growth-driven changes in grapes. Sugar development amps up and the colours change in the grapes themselves. Workers remove leaves and debris for ventilation and access to sunlight while thinning out clusters of grapes for optimal quality. Once September hits, sugar production becomes more intense and quick.

September – November

This is where the real fun begins! September is when Ontario wineries begin to harvest their crops for table wines and sparkling wines. This process continues through October and sometimes even November! We harvest different varietals at different times. The winemaker’s end goals for the grapes, and ripeness also influence when harvests happen. In October and November,  sweeter grapes for wines such as Late Harvest varietals and Icewine are protected from birds and the falls winds with thin, mesh and mesh-like netting.

November – March

A winemaker’s job is never done! Through November and December we see harvest for late harvest wines – how appropriate! Canada’s Icewine harvests run from late December to January but can come as late as February and March, depending on weather conditions.

Pondview Estate Winery explains some key points in the Icewine harvest process

Vines are dormant in January and February. This is when we do winter pruning to prepare for the upcoming growing season. As temperatures increase in March, vines will fall out of dormancy and sap will start to rise. Then, we get ready to do it all again!

Now you’re set with some high-level pieces of the Ontario grape growing process. Let us know what parts you’ve seen in-person and at what Ontario wineries in the comments!


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