You’ll lose some of the blooms whenever you cut back hydrangeas during the growing season, so the shrub may not look as full as it normally does. Cutting during the growing season always promotes new growth, so your hydrangeas will grow back to the same size and require regular maintenance.
Avoid pruning the stems later in the fall or winter on these varieties since you’ll remove the developing buds and get rid of next year’s blooms.
You can leave around 18 inches (46 cm) of the stems coming up from the ground to add support for the next season’s growth. Your hydrangeas will develop weaker stems after each time you cut them down to the ground, so you may need to tie the stems to bamboo or wooden stakes as your plants get older for additional support.
You probably won’t see many flowers or blooms during the first or second growing season when you’re pinching tips. Pinching the tips helps your hydrangeas develop a stronger base so blooms are more full during future growing seasons.
If you do need to add fertilizer, use a balanced time-released mix once or twice a year. If your hydrangeas have yellowing leaves near the middle of the plant, then apply a fast-acting fertilizer.
Growth retardants contain chemicals naturally found in plants that prevent branching and form buds. [8] X Research source Your hydrangeas will still grow to their full size eventually, but it will take longer for them to develop fully.
Make sure you completely cut through the roots before applying a vegetation killer, or else you could kill the part of your hydrangeas you want to keep.
You’ll still need to trim and prune your hydrangeas when they’re in pots to help control their size.
Dwarf hydrangeas look great when you keep them in pots.
