Every year it seems I either plant too early or too late, or just can't seem to keep anything alive. I am wondering when others start putting plants outdoors for good.

In Montana we have fickle weather and it can change the season of planting I assume? I do not have an actual yard so I use planters which can be a whole different game sometimes but in general I am curious when should I start putting flowers and other simple vegetables outside? Now I do know that each thing varies but just a general sense of when would be great.

Some people wait till mid may and others say May 1st. I know we get some cold days in May and of course you watch the weather to bring them in.