Plant a Rheingold arborvitae in a sunny to partially shady location that provides good drainage. Avoid low areas that collect runoff. Dig a hole about three times the size of the arborvitae's root ball. Mix the removed soil with an equal amount of compost, mixing well to form an even medium. Set the root ball in the hole, keeping the upper surface of the root ball level with the surrounding soil. Scoop in the amended backfill and tamp down firmly.
Water your arborvitae deeply to provide even moisture throughout the root system. Depending on your climate, you may need to provide supplemental water every one to two weeks.
Feed your Rheingold arborvitae in the early spring and mid-fall, beginning with the second year of growth. Use a granular or water-soluble fertilizer with a 10-10-10 ratio. Apply the fertilizer to the soil just above the roots, using caution to avoid contact with the foliage. These regular feedings will encourage optimal growth and color.
Prune this shrub in the winter. Trim off any uneven growth or unsightly branches that disrupt the overall shape and balance of the shrub. Check the shrub throughout the year for broken or diseased limbs and remove them as soon as they appear.
Check the Rheingold arborvitae for signs of spider mites. Although pests seldom disturb arborvitae shrubs, occasional mite infestations can cause damage. Examine the protected areas near the inner branches for signs of small webs that contain dead bugs. Treat a spider mite infestation with a pesticide labeled for use on evergreen shrubs.