The Mock Orange - Philadelphus varieties - are well known for their heady scent - especially on an early summer morning or evening! Correct pruning is essential for this group of early summer flowering shrubs.

Prune too early and you will lose the flower buds for the current year. Prune too late and the shrub will not have enough time in the growing season to provide flowering stems for the following year. Don't panic - we are here with information and advice upon when and how to prune your Philadelphus.

There are several Philadelphus - Mock Oranges - that need regular annual pruning in order to flower well with a spectacular display in early summer. We take you through the simple procedure of pruning Philadelphus to ensure that you have a stunning show of pure white flowers year after year.

Philadelphus Belle Etoile - One of the less vigorous varieties, noted for the light purple centre to the pure white flower. © David Hughes 2008

Most shrubs that flower at this time of year (early summer - image taken 17th June) depend upon flowering stems that were grown by the plant in the previous year (Growing season). If you prune Philadelphus too late - late summer or autumn- fall - for instance, then the shrub will not have enough time to make flowering stems ready for the following year.

The secret of correct pruning is not really a secret at all - You just need to know when and how to prune your Mock Orange Tree.

As soon as the shrub had finished flowering, cut out all of the stems which have just flowered. Prune them back to around a third of their length. They will soon start to produce new stems which will provide the flowering stems for next year. Do not just prune little bits off the end. Prune right back into the bush.

Once that bit of pruning has been done, then we (you) go on to the next stage of pruning. Pruning out around one in three of all the old stems - but right back to near ground level. We are talking about a few inches above the ground here.

The varieties of Mock Orange that can be pruned in this way include ... Philadelphus Avalanche, P. Beauclerk, P. Belle Etoile, P. coronarius Aureus - good hard pruning for this variety to get that beautiful bright golden foliage - Philadelphus Innocence, P. Lemoinei, P. maneau d'Hermine, P Mont Blanc and of course the double flowered Philadelphus Virginal - sometimes called P. Virginalis. All other Philadelphus that flower at this time should have pruning as above.

A great list of pure white flowers with varying degrees of scent!

This hard pruning of old stems, will prompt the shrub to send out new basal growths, which will provide good flowering branch framework for subsequent years, resulting in a fresh looking shrub. Do a further pruning of a third of old stems in subsequent years.

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.

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.

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.

Pests

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.

Newly Planted shrub not flowering

Diseases

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.