It may not be late for them to start sprouting. The Toronto area ranges from (US) zone 4 (furthest from the lake) to zone 7. If you are in a colder microclimate, everything in the cycle of a warm season grass will be behind warmer zones.

These types of grasses are known as warm season grasses, meaning they really do not start growing until both the soil and the air warm up to appropriate temperatures. Much of the country has experienced colder and later typical spring weather so not unusual for these grasses to be slow. All sorts of plants are several weeks to a month behind "schedule".

I live about 2 hours from Toronto and am in Zone 5a. I have many grasses that have no growth yet.
If they were Purple Fountain grass from last year they won't as it is just an annual grass. I assume you pruned them at some point.
You will just have to wait and see I am afraid.

Debbie