Do's and Don't of Pruning Hydrangeas
When pruning hydrangeas it is important to know what species of hydrangea you have. There are different ways in which hydrangeas bloom and should be pruned.
Also known as big leaf hydrangeas or mop heads, bloom on old wood. The best time to prune these varieties are shortly after their blooms start to fade and is recommended to prune very lightly, just underneath blossom, as pruning any harder will mean you are removing buds for next years blooming resulting in limited blooms or no blooms.
If shrub is looking unruly and want to prune back in order to reshape the shrub this is possible, the only set back will be you may not have as many blooms on next years plant, but the shrub should be more bushier and fuller looking. Prune back no later then end of July if hoping to see some blooms the following year.
Paniculata Hydrangeas (PG/ Limelight)
Also know as hardy hydrangea, Blooms on old and new wood, pruning back these varieties will not eliminate blooming for next year. These Hydrangeas should be pruned in the fall, winter or early spring. Pruning these varieties back by 1/3 of the plant size will ensure better form and shape, however harder back continuously each year may result in weaker stems in some varieties and may need to have more support as they bloom.
For pruning and plant maintenance, Annabelle is treated the same as Paniculata Hydrangeas. Often Annabelle hydrangeas are pruned in late fall to 3 inches above ground level, this does not eliminate any blooms for the following year and your Annabelle should be covered with blossoms next year. How ever this is a popular decision for most to tidy the shrub for winter months, it may make stems become weaker and require support if done every year.
Dead heading is NOT pruning. How to know if your pruning right?
This is Dead Heading, not pruning.
Deadhead in summer by removing the spent blooms, follow the blooms stem down to the first break (set of leaves) and cutting just above the break, image to the left.
If dead heading in early spring you will follow the blooms stem down to the first set of buds emerging from the stem. Cut just above these new buds emerging, photo on right.
Proper pruning of hydrangeas
Macrophylla Hydrangeas or also known as Mophead hydrangeas, are commonly just dead headed each year, but if necessary to prune for reshaping or filling out your shrub then you can cut further down the branch, be sure to check for at least two breaks of buds or leafs, then cut above the second set. This will not hurt the shrub in any way but may result in next years buds being cut off leaving that stem green for the following year. If dead or damaged wood is present on shrub you should remove theses branches at anytime of the year to detuor insects or diseases for getting into your shrub.
Paniculata Hydrangeas (PG/ Limelight) and Annabelle hydrageas
Shrub in end of summer is full lush and lots of blooms in flower. To ensure of a full well shaped and branched specimen this shrub should be pruned down to 1/2 the size it is now. Remember it is important to make sure you leave at least TWO breaks (buds, or leaf breaks) on the stem you are pruning. This however does not apply for Annabelle hydrangea in which that variety can be cut to three inches above ground level with no worries of break left, as Annabelle will grow from the ground up again.
This is the same shrub as above, black lines have been added to give you a sense of size this shrub will be pruned back to this fall/winter. It is important to prune just above a break (set of bud or leafs) in the steam, try not no leave too much stem above the break when pruning as this leads to dead wood which is more susceptible to bugs a diseases entering the shrub.