Deadheading, or cutting off the flowers, won’t harm viburnum. However, doing it isn’t necessary and prevents the plant from growing berries.
At most, remove no more than ⅓ of the shoots. Usually, this means removing 1 to 3 shoots at a time. Leave behind the thinner, fresher shoots coming up from the plant’s base. These will rejuvenate your viburnum. Although the snowball flowers bloom on old wood in viburnum plants, the oldest shoots produce weak flowers and are safe to remove.
Remember to only perform hard trimming in spring, after the bloom, to avoid damaging the bush’s buds the next year. You can trim the branches this way to maintain the snowball bush’s rounded shape or sculpt it into a hedge.
The best time to do this is around May, after the flowers bloom, although it can be done anytime as needed. After trimming back the plant, you may want to wait and watch it grow back. Then you can see where you need to thin out the branches. By maintaining the bush regularly, you likely won’t need to do this.
This routine trimming should be done year-round to keep your snowball bush healthy and thriving.
Hydrangeas flower on new wood.
You can cut snowball hydrangeas to the ground every year. This usually isn’t necessary and can weaken your plant over time, so only try doing this every 3 or 4 years. You don’t have to deadhead hydrangea since you remove the old blooms when you trim back the branches.
Try to trim some of the old branches back every fall so your hydrangea always has fresh growth.
Through routine maintenance, you can reduce the amount of pruning you need to do in the fall.
