Native to New Zealand, "Silver Sheen" kohuhu (Pittosporum tenuifolium "Silver Sheen") is a fast-growing shrub with dramatic silvery highlights to its glossy foliage. Hardy in U.S. Department of Agriculture plant hardiness zones 8b through 10, "Silver Sheen" prefers well-drained, sandy soil and full sun. In hotter climates, some protection from intense early-afternoon sun is needed. "Silver Sheen" has nearly-black stems and olive leaves with silvery undersides, giving the shrub a shimmering appearance in gentle winds. Purple-red flowers shine against the foliage in late spring. "Silver Sheen" is best planted in early spring before its flowers bloom.
Plant "Silver Sheen" in a sunny to partially shady area of the garden. Ensure that the site has more than enough height for a plant that will grow 20 feet tall and 8 feet wide. The plant can be grown in coastal areas in full sun and is not bothered by rabbits or deer. Provide shelter near the house or other larger plants in the cooler climates of its hardiness zones.
Work an area of soil that is 3 feet square, using a shovel. Mix in 3 inches of compost to a depth of at least 8 inches. Rake the area smooth and remove roots or rocks. Check drainage by digging a 6-inch trench and filling it with water. Allow it to drain and fill it again. If it has not drained in 30 minutes, mix 2 inches of sand into the soil in the area to improve drainage.
Dig a hole twice as deep and twice as wide as the "Silver Sheen" root ball. This enables the soil to be loosened so new roots don't struggle as they spread. Remove the plant from its nursery pot and gently tease out the roots. Spread the roots in the hole and back fill, pressing the soil firmly around the roots. Fill the hole to cover the roots well, but do not mound the soil against the trunk of the bush.
Water the plant to settle the soil. Water regularly to a depth of 18 inches, allowing the top 7 inches of soil to dry before watering again. Two weeks after planting, feed the plant a high-phosphorus, granular fertilizer such as 5-10-10 to initiate root formation. Broadcast 1 tablespoon of fertilizer for a 1-gallon-container plant. Use 2 to 3 tablespoons for larger shrubs. Each spring, fertilize "Silver Sheen" with a slow-release, balanced fertilizer such as 10-10-10 at a rate of 2 to 3 tablespoons per 3-square-foot area around the shrub. Wear gloves and safety goggles when applying fertilizers.
Prune "Silver Sheen" as needed to retain the desired size. Without intervention, the plant regularly grows 10 to 15 feet in height or more. However, its small leaves respond well to pruning and shearing for a smooth appearance. Prune "Silver Sheen" in late winter or early spring, when the plant is semi-dormant. Use pruning shears or hedging shears, and prevent the spread of disease by sterilizing the blades with household disinfectant before and after you prune. Wear gloves, long sleeves and safety goggles when you prune.