The column-shaped arborvitae "Elegantissima" (Thuja occidentalis "Elegantissima") is one of the lesser-known arborvitae varieties. During most of the year, the plant has medium to dark green foliage with golden-yellow tips that turn to a striking shade of bronze in winter. It is relatively free from most disease and pest problems, although it may experience canker, spider mites or bagworms. "Elegantissima" arborvitae grows in U.S. Department of Agriculture plant hardiness zones 4 through 8. You can use this deer-resistant tree in borders, landscaping beds, hedges and or to form a privacy screen.
Choosing a Planting Site
The slow-growing "Elegantissima" arborvitae prefers average or slightly sandy well-draining soil, but it can tolerate and thrive in a variety of soil conditions, including acidic soil, slightly alkaline soil, clay, loam and sand. Like all arborvitaes, "Elegantissima" can grow in areas that receive some light shade, although it prefers between six and eight hours of direct sun daily. When arborvitaes get too much shade, it affects their growth, giving them leggy branches and an open structure. When planting an arborvitae, you only need to amend the soil if it is very poor, advises National Gardening Association. Otherwise, it can be planted directly into the garden.
Like most plants, "Elegantissima" needs roughly 1 inch of water weekly once it is established, but may need more water during its first growing season. In the first year, let the first few inches of soil dry out before watering the plant again. When watering "Elegantissima," provide enough water so you moisten the soil all the way to the bottom of the root ball.
Fertilize "Elegantissima" arborvitae twice yearly -- in early spring and the middle of fall. Use a water-soluble or granular fertilizer in a 10-10-10 or 6-12-12 formula. Use 1/2 to 1 pound of granular fertilizer for every 100 square feet of planting area, or according to the directions on the label. When applying a granular fertilizer, spread it out to cover the plant's root system, which is usually the plant's height multiplied by 1 1/2 to 2. For example, if the tree is 10 feet tall, the root system will spread out 15 to 20 feet. Time granular fertilizer applications right before a soaking rain is predicted or water the area with roughly 1 inch of water to help the soil absorb the fertilizer.
Although "Elegantissima" is a fairly low-maintenance plant, it is susceptible to several pests, including bagworms, which can create substantial damage. Inspect the plant periodically for evidence of insect infestation and treat affected plants as soon as possible. Bagworm eggs can be picked off by hand, while small larvae are effectively treated by spraying the surfaces of the plant with insecticides such as neem oil. Horticultural oil can help prevent and control spider mites, which can kill trees. Mix horticultural oil or neem oil at a rate of 2 1/2 to 5 tablespoons in 1 gallon of water, or according to the instructions on the label. Apply it with a garden sprayer to every surface of the plant, applying it twice in a two-week period. Follow all safety instructions when using garden chemicals.
You don't generally need to prune "Elegantissima" arborvitae, but you may need to occasionally do a light trimming to maintain the shape or remove diseased, damaged or dead limbs. Pruning can be done at any time of year, although Cornell University Extension of Schenectady County recommends pruning arborvitae in early spring. Always use sharp pruning tools that have been disinfected by soaking them for five minutes in a solution of 1 part bleach and 3 parts of water.