Answer: You can plant anytime the ground is not frozen. Spring is an excellent time, followed by autumn. Both seasons offer plentiful natural rainfall to help the roots become established. You can plant your Thuja in native soil or, if it doesn't drain well (or drains too well), mix in some organic matter prior to planting. Be sure to water well after planting to help settle the soil and remember to water deeply once each week (if rainfall is sparse) to help the roots become well established.
Best wishes with your landscape!
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