All the roses in the nursery are marked with a single number that represents a "hardiness zone" -- a simple way to describe how well a species will survive our climate. The zone represents the average minimum winter temperature: Ottawa is in Zone 5, the Upper Ottawa Valley is in Zone 4.
The lower the number a plant has, the hardier the plant. Any rose marked Zone 5 will usually survive the winter here; Zone 3 and Zone 4 roses are even more hardy. But, some Zone 5 plants and all Zone 6 plants will have a hard time surviving, even though they may thrive in Kingston or Toronto or even in Perth. [If a rose won't grow here, I won't sell that variety]
You can get some idea of how the growing seasons differs in this area from other parts of Ontario:
What plant zone are you in??
Note: if you're looking at "zone maps" from the US, remember that they use a different system than in Canada. Typically, a Zone 4 plant from a US source will be a Zone 5 plant in Canada. A Zone 5 plant in the US will be a Zone 6 plant in Canada.
Survival of plants is affected by many factors in addition to low winter temperature "zones":
With so many factors affecting how well plants thrive in our climate, its difficult to specify exactly how a particular plant will do in a specific planting site. The "zone number" is a good general guide to hardiness, but if you have questions about a particularly difficult site, please feel free to ask me. I do indicate on the rose labels which varieties are particularly suited to difficult growing conditions.