The mock orange (Philadelphus coronarius or Belle Etoile) is a medium-sized shrub that features fragrant white flowers in spring. This plant, which prefers full sun or partial shade and well-drained soils, is meant to have an upright and rounded form, often with arching branches. The mock orange requires annual pruning in order to maintain good form, particularly if the shrub is used as a border or screen.
Ideal pruning time
Mock orange is a spring-flowering shrub that produces buds in the autumn to bloom the following spring. Prune mock oranges as soon as possible after the shrub has finished flowering in spring. Pruning at this time will ensure fast healing wherever cuts are made and dead branches are still visible and easily eliminated. During this annual pruning, remove any weak, diseased or damaged branches first and then work from the top down to shape the shrub. Use pruning loppers or a saw to remove a quarter to one-third of the canes at ground level.
When not to prune
Do not perform an annual prune on mock oranges in late summer, autumn or in spring before the shrub blooms. Pruning at these times will remove many flower buds and severely limit blossoms the following spring. Late-season pruning can also make the mock orange susceptible to cold damage. Mock orange shrubs can suffer from tip kill in colder weather. The only exceptions may be light, corrective pruning for maintenance or hedges.
Corrective or maintenance pruning
Mock oranges can be pruned minimally throughout the year to remove any diseased, broken or dead branches. If the mock orange is grown as a hedge or screen it may require multiple prunings in the spring and early summer to maintain an attractive shape.
After several years of growth, a mock orange shrub may benefit from a rejuvenation pruning, particularly if the shrub was not pruned regularly and, as a result, became spindly and unkempt-looking. Perform a rejuvenation pruning in spring before the mock orange leafs out. Cut off all of the stems as close to ground level as possible. There will be no blossoms for a year following this severe pruning but vigorous growth will emerge and you can shape this as desired.