Hydrangeas are easy-care shrubs that will bloom profusely from summer to fall if you treat them right. The first step is knowing whether or not your Hydrangea blooms on old wood or new, and that is dependent on the variety.

Hydrangeas that bloom on new wood

Most hydrangeas that perform reliably in the Ottawa area bloom on new wood, meaning flowers appear on the new growth that your hydrangea has produced in the current season. You can safely prune these shrubs in spring or fall, and your shrub will still reward you with blooms in the summer. These are Hydrangea arborescens and Hydrangea paniculata.

Hydrangea arborescens varieties include the classic Annabelle, Incrediball, and Invincibelle hydrangeas. You can safely prune these varieties down as far as 25 cm/10 inches from the soil in spring or fall.  This will improve the shape of your shrub and improve flowering.

Hydrangea paniculata varieties include Pee Gee, Limelight, Quickfire, Bobo, and Pinky Winky. These varieties have much woodier, stronger branches than arborescens varieties. Take out any dead or damaged branches in spring, and observe the ¼ out, ¼ back rule* when pruning for shape or tidying up your Hydrangea paniculata.

Hydrangeas that bloom on old wood

Hydrangea macrophylla and petiolaris varieties bloom on old wood, meaning growth from the previous season. If you must prune these varieties, do so immediately after flowering or in spring when any winter kill or damage is easy to spot. Look carefully to make sure you are not pruning off any flower buds, and use the ¼ out ¼ back rule.

Hydrangea macrophylla varieties include Endless Summer, Twist and Shout, Blushing Bride, and the Cityline series. Hydrangea petiolaris is climbing hydrangea.

Changing Colours

You can change the colour your Hydrangea macrophylla blooms by adjusting the pH of your soil. Craving a blast of pink? Make your soil more alkaline by adding a “soil sweetener”. Blue more your style? Acidify your soil. It’s easy to do, and there are several products available specifically for this purpose.

Want to know more about hydrangeas? Visit us at 4590 Bank Street, Ottawa.

*See our pruning video here for the ¼ rule and more tips.