A bit late (but I was too busy working in the garden): Mother's Day was yesterday (9 May 2021) and it is usually a rough guide to when tomatoes can stay outdoors here in the Lower Mainland. Assuming you start your own seeds indoors, and then harden them off slowly, yesterday was the day to leave your Tomato plants outdoors full-time. So that is what I did. Instead of putting them out in the morning and bringing them back indoors in the evening, they are now outdoor plants. Whew! One more milestone among the many Spring activities.