At a minimum, you want to avoid any frost or freezing temperatures. I play it fairly cautious and bring mine out in early May. But I have a lot of them (about 13), and some of them are quite large and heavy, so they won't get put somewhere else every night, and I don't want to have to drag them all into the house if frost threatens.

They start the spring on a covered east-facing porch, gradually moving down towards the sunny end, then onto the deck for more sun, then out into the yard. It takes several weeks for the whole progression. This is to make sure I don't sunburn the leaves.

i have mine inside in winter in 50F so when its 50-59 in shade i take them out . i have all of mine outside now . and if its get lower then 41F i cover them and if its gets lower then 32F i take them inside . and then i take them inside when it gets 41F in the shade . this past november they even got snow on there flowers and light frost but it dint hurt them

Thanks! I think mine are ready for the great outdoors--at least, I am!

I put my tropical out after Mothers Day in May every year.
Never had a problem with it.