Mock orange is a fragrant, deciduous flowering shrub, which has several uses in landscape design. It can be used as a specimen planting, hedge or privacy screen along a deck or patio. Mock orange is easy to grow and requires little maintenance. Pruning will encourage new growth resulting in a much denser shrub.
There are several varieties of Philadelphus or mock orange, including sweet mock orange (Philadelphus coronaries), little leaf mock orange (Philadelphus microphyllus) and Philadelphus virginalis. The plant size varies according to the cultivars, which range from 3 to 20 feet in height. This plant blossoms in spring with orange-scented white flowers. Most cultivars have green foliage, with the exception of 'Variegatus', which has green leaves with a creamy white border, and 'Aureus', which has yellow foliage. Mock orange has a rounded shape with arching branches. This shrub is native to Europe, and it is hardy in zones 4 to 8.
Mock orange does well when planted in full sun to partial shade. It requires moist, well-drained soil, and it will tolerate alkaline soils. When planting cultivars such as 'Sweet' mock orange, which grows to a height and width of 10 to 12 feet, be sure to allow enough room for the shrub to grow.
Mock orange is typically not a heavy feeder. Nutritional deficiency can occur when it is planted close to other shrubs; signs of nutritional deficiency are low growth and yellowing of the leaves. The best time to fertilize the mock orange is in late February or early March. It can also be fed in late June to early July. It is recommended that you apply a 10-10-10 or 12-12-12 plant fertilizer at the drip line and water after the application.
Timing is everything when it comes to pruning the mock orange shrub. Flowering generally takes place in early summer, with the plant producing flowers on stems from the previous growing season. New plants should only be pruned after their second year of growth. Prune a mature shrub after it has finished flowering. It should not be pruned in late summer or early fall, as it needs time to produce the flowering stems for the following year's blossoms. Prune the stems that have just flowered back to 1/3 of their length. Also prune out some old stems of the shrub, which causes the plant to produce new growth and ensures flowering wood. Cut out one in every three old stems down to 2 inches above the soil level.
Aphids can infest the mock orange shrub, but in most instances they do not pose a serious problem. The natural predators of aphids are the ladybug, lacewings and parasitic wasps. Generally, these insects take care of the aphid infestation. You can also apply a strong stream of water to knock the aphids off of the shrub. Mock orange is susceptible to gray mold, wood rots and decays, leaf spot and powdery mildew.