You have houseplants like geraniums that want to spend the summer outside.
You have seeds that you started inside.
All of these plants need to be slowly acclimated from their nice pampered existence indoors to the harsh realities of the mountain climate.
|Houseplants and seedlings hardening off in the shade|
I recommend first putting them outside on a cloudy day or in the shade, in order to expose them to wind.
Then expose them to gradually increasing amounts of sunshine - dappled first (if you can find it), then full sun, then longer periods of full sun.
Of course, at this time of year, there's always the threat of frost, so even after the plants toughen up a bit, I watch the forecast, and bring them in if it threatens to drop below freezing. Hence "the dance".