Growing Arborvitae in Containers
I live in Salem Oregon. Last year I bought 6 Emerald Green arborvitae and planted them each in 5 gallon black plastic nursery pots. I used good soil and compost. They are lined up along the edge of my patio, facing west. The patio has an overhang, and there is a large tree to the south that is near the patio. The arborvitae get sun all day once the sun is overhead. This year, they look healthy, with new growth on the tips. Problem: the tops are flopping over to one side, toward the west. Why is this? Should I turn the pots around to get the tops to go straight? Is it because I have them in pots? (I can't put them in the ground- I live in a condo and we can't plant trees or shrubs).
The arborvitae should do fine in the black pots for several years. Light is most likely the problem. The plants are following the light that arrives at your patio mid day and sets in the west. Turn the pots to encourage upright growth. You should also avoid high nitrogen quick release fertilizer that can promote excess top growth. Consider using a low nitrogen slow release fertilizer like Milorganite. It releases small amounts of nutrients throughout the season. Better for your plant and easier for you.