Q: I recently purchased two dwarf-looking little shrubs with a named spelled like Thuia (or Thuja) Homstrup. I hope to keep them in containers on the patio throughout the year.
I remember the nursery salesperson saying that if I planned to keep them outside I’d have to double-pot them. Can you advise how best to do this?
A: The real name of your plant is “Thuja orientalis” ‘Holmstrup’. The “j” in “Thuja” is silent, so the word is pronounced “THEW ya”. The shrub may be small now but it can grow six to eight feet tall if planted in the ground. It will remain smaller in a container but I would still expect it to be at least four feet tall eventually.
Double-potting is just like it sounds: Buy a bigger pot (at least 6″ wider at the top), making sure it has a drain hole. Fill it partially with soil conditioner. Put your present pot inside the bigger one.
Add soil conditioner until the rim is level with the rim of the larger pot. Fill the space between the two with more soil conditioner. The roots will be well protected for winter and you can slip the pot out when spring comes.
Eventually you can use the bigger pot as the next home of your Thuja.