Philadephus, or mock orange, is a deciduous to semi-evergreen (some southern cultivars) shrub. The flowers have a delightful citrus scent. There are several types, from dwarf varieties 1 metre (3 feet) high up to standards of 7 metres (20 feet). Once an old favourite seen in many gardens, easy-care mock orange has been rediscovered. Because they have a tendency to get "leggy," mock oranges need pruning to direct growth and maintain their appearance.
Trim out at least one third of old growth on established mock oranges, according to gardening expert Ed Hume. Trim mock oranges in early summer after they have flowered.
Remove old wood that flowered the year before. Remove interior unwanted branches using lopping shears. Remove unwanted trunks by cutting out at the base of the ground with a pruning saw.
Thin out by completely cutting unwanted branches back to the trunk. Trim severely overgrown mock oranges further, using heading cuts. Cut the growth tips of branches back to side branching shoots. Do not leave a stub between the side shoots; cut the tip completely back to its base.
Leave young ground level shoots to replace cut out trunks if the mock orange needs rejuvenation. Inspect and head back new growth the following year as needed to maintain shape and size.
Remove any broken, diseased or split branches. Remove in-crossing branches that will spoil the mock orange's shape.
Prune newly planted mock oranges only after the second year of growth. Thin new shoots in early summer to encourage a good shape and structure.
Remove any weak, overcrowded growth. Trim to keep the plant from becoming leggy by using heading cuts.
Prune to open the mock orange up. Remove crossing or awkward inner branches back to the main trunk. Always remove dead or splitting branches and twigs and diseased growth.
Pinching shoot tips out will make a mock orange produce more side branches for a bushier shape. Use thinning cuts to clean up a mock orange's shape. Thinning completely removes branches to a main trunk or to the ground. Use heading cuts to create a fuller shrub. Heading is cutting back to a growth bud, and encourages lateral growth.
Never leave stubs. Cut as closely to the branch as possible to promote rapid healing. Pruning late in the fall or during dormancy will cut off flower buds and you will have fewer blooms in spring. Avoid shearing mock oranges.