whens the latest i can grow untill

Hey guys, i am located in southern ontario and just wondered whens the latest i can grow untill, seeing as my plants need more time. is it first frost they die?

Outdoors this time of year is hard because the days are getting shorter and idk if you mean Ontario, Canada or Ontario in Los Angeles but Canada i would imagine it'd get way too cold.
Indoors you can grow year round.

You can extend the growing season by covering your plants with those 55 gal contractor trash bags at night. If a frost advisory/warning is in effect for a given night, just cover the plants in the evening/afternoon and then remove the covers in the morning. I think it also helps to lay some black plastic around the base of the plants. The black plastic will pick up and hold heat from whatever sun there is and release the heat back at night.

This applies to a soft frost, where the temp might hover around freezing or just below it. For a hard frost, I guess it's just harvest whatever you can.