Philadelphus – or Mock Orange, to give it its common name - gets its fair share of bad press, as well as often being suggested as being one of the better fragrant shrubs. The reason for the bad press – from my own mailbox experience – is the widespread planting of the famed Philadelphus ‘Virginal’ or as was known Philadelphus virginalis.
This variety is one of the largest growing of the group, and probably most fragrant, with pure white double flowers. But, after the relatively short flowering period – about 2 weeks maximum – you are left with a rather dirty-green shrub, which simply grows to around 10 feet (3 metres) in height and almost the same in spread!
Whilst many other shrubs are happy to give a secondary interest with autumn foliage colour, this one does little more than turn a few leaves to yellow before they depart to the ground to be recycled.
After leaf fall you are left with an untidy mass of stems for up to five months. Winter always seems to be a good time for Pruning Philadelphus, but is in fact the worst time to do it. By pruning in the winter, you are cutting off all of the following years flowering stems! This wrongly timed operation alone is probably responsible for much of the shrubs’ bad name. They should be pruned if needed right after flowering.
Mock Oranges are happy to grow in most garden situations, being tolerant of full sun or even dappled shade. I have seen quite a few growing happily in a woodland garden also. Soil type is rarely an issue for they are at home in most soils and are reasonably drought tolerant.
Philadelphus can be planted at most times as they are normally sold as container grown shrubs, however, buying the shrub when in flower is probably not the best time, for you will then be planting and having to establish it at the start of summer. Late Summer, Autumn or early Spring would be my choice.
All of the Philadelphus have white flowers – some single cup shaped with solitary blooms. Others fully double, and absolutely smothering the bush an a mass of white. The flowering time depends upon choice of variety, but all flower between late spring and mid-summer.
Once you follow these basic instructions about how to grow mock orange, you will be rewarded with a bush that is full of flower in late spring, and tidy in growth throughout the rest of the year.
Aphids – both greenfly and blackfly can be a problem, and soon cause the foliage to twist into an unattractive mess if not treated with spray.
The Philadelphus is normally only susceptible to powdery mildew. This is especially the case in dry springs and summers.
Philadelphus root quite easily from either softwood cuttings or semi-ripe cuttings. Together with this they can be propagated by hardwood cutting in early winter. The latter is easiest, for there is no need to worry about flagging foliage as with the earlier cuttings.
Sowing seed is not really an option.