How to prune philadelphus

If not cut back, many shrubs will steadily increase in size to become a dense mass of twiggy stems, outgrowing their welcome and holding any blooms at the tips of branches.

Spring shrubs like philadelphus bear their flowers on short sideshoots that are produced from strong stems made in previous years. But this doesn’t mean that you have to leave all the old growth in place. Removing the oldest, thickest stems right down to the ground will reduce the height and spread of the shrub, and make space for younger growth to develop and flower next spring. It will also encourage the development of new, strong shoots from low down on the plant that will take over in future years.

This process will produce different ages of growth, over a cycle of around three years. In the first season a shoot will grow from the base of the shrub. In the second, it may produce a few flowers, but will grow taller and produce sideshoots. In the third season, it will flower well. Then the whole woody branch can be pruned out to allow the next succession of stems to take up the blooming baton.

Follow these easy steps to prune your philadelphus and improve its flowering performance.

You Will Need

• Secateurs
• Loppers, May be required for the thickest stems

Step 1

Assess the overall shape and condition of the shrub before you start to prune, identifying and removing any dead and broken branches. Use secateurs to cut back these as low to the base as possible, pruning to a bud or healthy stem.

Step 2

Prune out three or four of the oldest, thickest stems. Use secateurs (or loppers for thicker branches) to cut these low down, close to the soil. This will encourage the growth of new shoots to ensure a succession of flowering stems in future years.

Step 3

Thin out the younger stems, cutting them down to ground level and leaving up to eight of the strongest to carry flowers next season. Also remove any that are thin and weak or crossing, and choose to leave those that are evenly spaced.

Step 4

Reduce the height of any tall, older stems by around a third. Use the tip of the secateurs to cut back the arching end of the branch to a strong side shoot. This will reduce the weight of the foliage and stop branches from flopping onto nearby plants.

Step 5

Give the plant a last check over, taking out any branches growing in the centre of the bush to maintain good air circulation, and ensuring that you're happy with the resulting shape.

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