I posted this somewhere recently....
The second the buds start breaking and leafing out, if daytime temps are over 55º, they're outside during the day in full sun on a south-facing wall of my house. Any time the weather calls for overnight temps below 40º or excessive rain, they come back inside. If you can manage to get them directly into full sun as they're starting to leaf out, they won't need to be slowly brought into the sun ("hardened off"), and you won't need to worry about leaf-scorch.
I realize how daunting it may be for some to pull dozens of plants out into the sun on a few days of rollercoaster weather. I use plastic bun/loaf trays you find in your local bread stores, it's a 2'x2' tray, like this: http://www.wasserstrom.com/restaurant-supplies-equipment/Product_914301
The trays have two handles for easy carrying and each tray holds 10 one-gallon pots pretty easy.
After I sold my '68 Chevy pickup, I realized the wooden rolling dolly I kept the assembled front clip (front end) on would hold three trays perfectly. It has inflatable tires on it from Harbor Freight or Northern Tool and rolls on rocks and dirt well. I roll it to my side yard with 3 trays, pop the trays in one of my raised beds, then roll back in and get more! Works like a champ. Also saves my back!
Here are pictures of my 4 trays full of trees and my 3-4gal pots, taken yesterday. Already have a good 4" of growth on some of them, after 10 days.
