Q.What size container for evergreens
Can Wichita Blue Juniper and Forever Goldy Arborvitae be grown in containers in zone 7b? If so, what size of container to choose for 2’ tall arborvitae and 4’ tall juniper? (They are both cultivars that do not grow above 10’ tall, and I am fine with them staying small for my balcony container garden)
Certified GKH Gardening Expert
Since both of them are hardy to at least two zones lower than yours, they should do fine. The answer also depends upon what size container they're in now. You'll only want to repot them to the next larger sized pot or, if they're not in pots, you should be able to dig the hole twice as wide and deep as the root ball. The height or width of the pot should be about 2/3 the height of the plant for stability. These plants may become pot-bound and need their roots trimmed in order to keep them the size you want. You may want to mulch around the base of the plants if you're expecting a cold winter.
Here's a good article that should be helpful: https://extension.psu.edu/programs/master-gardener/counties/lackawanna/news/2015/container-grown-trees-and-shrubs-2013-fix-those-roots-before-you-plant