Question
Can cedar shrubs and trees also be kept from outgrowing their 5cu.ft. planters?
Can they be overwintered in planter?Is it ok to winter them in above freezing
garage without light or growing lamp or is it better in the cold with natural
light.? Must there be watering  in winter in any one of the above conditions?

Answer
Ed,

While it is possible to maintain the top by pruning to keep it small, there is little to do to keep the root system from out growing the planter eventually. With proper maintainance, they should be fine for 5-10 years.

You can overwinter the plants in the garage, this would protect them from any wind burn that they might receive outside. If you keep them inside, make sure that you water them through the winter.

Good luck,
Ed Gulliksen