The arborvitae (Thuja) is a group of evergreen trees and close relatives of the cypress. Planted close together, a group of arborvitae will grow together to provide an attractive, living privacy screen. The different species of arborvitae give the gardener a choice of shapes from which to choose: globe, columnar and pyramid. Arborvitae thrives in cold climates and is hardy to USDA zones 2a to 8b. Harvest your cuttings in mid to late winter.
Look for growth from the current season that is growing from an older branch. Researchers at the University of Florida suggest taking your cutting from the lower part of the plant. Pull the shoot sideways from the older branch and yank on it, so that you get a piece of the older wood with it. This is known as a heel cutting. Cut the branch so that it is 6 to 9 inches in length.
Fill planting pots with coarse sand. Water the sand well and allow the excess water to drain from the bottom of the pot. Poke a hole into the sand to accommodate the cutting.
Dip the heel end of the arborvitae cutting into the rooting hormone and then insert it into the hole in the sand.
Place the potted cutting into a plastic bag, leaving the top of the bag open.
Place the bagged cutting on the heat mat, set to 75 degrees F.
Check the soil periodically and mist it with the misting bottle if it feels dry. The cuttings should root within six weeks. If a gentle tug on the cutting meets with resistance, it has roots and you can remove it from the mat and the bag.