Japanese stewartia (Stewartia pseudocamellia) makes an attractive ornamental tree in temperate gardens. In the summer, the tree produces white blooms similar to those of a camellia shrub. In the fall, it puts on a show as its leaves change from deep green to yellow and red. Although stewartia is a hardy tree without any known pests or diseases, no tree is immune to these problems. Taking a few precautions will keep your tree healthy.
Establishing Japanese Stewartia
Japanese stewartia does not establish itself as readily as do other common garden trees and shrubs, and this can lead to problems with the tree falling over. Plant the tree in the spring rather than the fall so it isn't toppled over by winter storms. Provide supports for young trees to stabilize them. For strong root development, water the tree deeply once a week for the first month, then water only after the soil dries to a depth of 3 to 5 inches. During the first two years, trim back new growth to encourage root development.
Japanese stewartia prefer acidic soil that drains well. They will tolerate clay soil, but the tree will do better if you amend heavy clay soil with sand and compost. Stewartia trees grown in neutral or alkaline soil will have difficulty taking in necessary nutrients, which leads to nutritional stress. This stress weakens the tree and makes it more susceptible to pests and disease. Amend neutral or alkaline soils with peat moss or conifer needles to lower the pH.
The leaves of Japanese stewartia will burn if exposed to strong afternoon sun. The tree prefers shady or partially shady conditions and can handle morning or evening sun. However, a stewartia planted in full sun will experience leaf burn and won't grow as strongly. This heat stress weakens the plant and increases the likelihood of pests or disease. Always plant your stewartia where it will be shaded during the hottest part of the day.
Damaged bark on any tree is an invitation to pests and disease. The problem increases with Japanese stewartia because it has thin bark that can be easily damaged if you run into it with a lawn mower or other lawn equipment. When working around your stewartia tree, use extra caution not to hit it. To add an extra layer of protection to young trees, place a short fence around the trunk.