We have beautiful tall Mock Orange bushes that have been growing beautifully and flowering well for 20 years.
Every year in the spring there is a lot of dead branches.
I always trim them back.
Is this the correct procedure or should I leave them?
Thank you for contacting the Toronto Master Gardeners. Your Mock Orange shrubs sound really lovely, and healthy! Mock Orange (Philadelphus coronarius) benefits from annual pruning to encourage strong healthy shoots and improve flowering. Annual pruning also prolongs the life of these plants. Mock Orange blooms on the previous year’s growth, also known as ‘old wood’. Therefore, they should be pruned immediately after flowering, because if you wait too long to prune, you run the risk of cutting off the buds for next year’s flowers.
Dead or damaged wood can be removed at any time, so removing it in the early spring as you have been doing is fine. These stems should be removed right to the ground or to their point of origin. You could remove dead or damaged wood at the same time as you do annual pruning, right after flowering, so that all of your pruning is done at the same time.
Typically, annual pruning consists of:
- Removing dead or damaged wood
- Removing some stems right to the ground if the bush looks congested, to improve air circulation.
- Removing any weak stems right to the ground, so that the plant focuses its resources on strong new shoots that will produce the best flowers.
- Remove flowered growth above an outward facing bud
- Shape the bush as needed
As Mock Orange shrubs mature, they can get overgrown. This can be prevented by cutting back up to 20 percent of aging stems to near the base each year. If a Mock Orange is severely overgrown, there are two ways to rejuvenate it. The first is to rejuvenate in stages, over the course of three years, by cutting one-third of the oldest stems down to the ground, at the time that you do your annual pruning, each year for three years. After three years, you will have a healthier looking shrub. The second way is drastic pruning, which is cutting all of the stems to ground level in the spring. You will not have flowers that year and maybe not the next, but you will soon see healthy growth at the base as the shrubs quickly grow back.
I hope you enjoy many more years of blooms and fragrance from your Mock Orange shrubs !