When is a flawless time of the year to plant a satsuma (orange) tree? ...

Clover corral?
Answers:    Spring after the last of the frosts if you live surrounded by a cold area. If you are surrounded by the winter in your chunk of the world now and can prepare the site, do it beside lots of organic matter. (eg manures and grass clippings etc). It will make a contribution your tree a fantastic start when you plant.