The arborvitae is an evergreen tree and shrub that produces flat foliage that is scale-like in texture. The tree grows to 50 feet and is hardy in USDA growing zones 4 through 9 depending on the variety. Arborvitae grows best in a nutrient rich soil that is well-draining and has partially shaded light conditions. Propagate the tree or shrub by taking semi-hardwood stem cuttings during mid-summer through early autumn.
Cut 6-inch semi-hardwood stem sections from the arborvitae tree with a sharp knife or pruning clipper. The stem section should be from current year growth that is beginning to firm with mature sized foliage.
Mix together equal quantities of sterile peat moss, course sand and perlite to create a rooting mixture. Lightly moisten the mixture with water and fill it into a rooting tray.
Clip all foliage off the lower half of the arborvitae stem. Dip the cut end of the stem into powdered rooting hormone and gently tap to remove excess powder. Stick the stem into the rooting tray to a depth of 2 to 3 inches. Firm the soil around the stem to hold in place. Space the cuttings several inches apart so they do not touch.
Mist the rooting medium with a water filled spray bottle and cover the tray and cuttings with a plastic bag. Set the tray in a warm location or on top of a heated propagation mat to keep the soil warm during the rooting process.
Gently pull on the arborvitae stems four to six weeks after the start of the rooting process to see if there is resistance from the formation of roots. Grow the stems in the rooting tray until they reach a length of 1 inch.
Transplant the cuttings into individual planting containers filled with a good quality potting soil. Grow the cuttings indoors for the first year then plant the cuttings outdoor in the spring season to give them time to establish before winter.