Question asked, "When do I prune hydrangeas?

     How to Prune Snowball Bushes
Several hydrangeas and a viburnum are known as snowball bushes.
 The term “snowball bush” is an example of the confusion caused by the use of common plant names based on appearance or features. Chinese viburnum (Viburnum macrocephalum), Annabelle hydrangea (Hydrangea arborescens "Annabelle") and panicle hydrangea (H. paniculata) are all called snowball bushes. In Southern gardens, smooth-leaf hydrangea (H. macrophylla) is also called snowball. Prune these shrubs based on how they form their flowers. Annabelle and panicle hydrangeas form blooms on new wood each summer, but Chinese viburnum and smooth leaf hydrangea bloom earlier on last year’s growth.
 
Things You Will Need
◾Hand pruners
◾Pruning shears
◾Pruning saw
◾Bleach or rubbing alcohol
◾Mixing bowl and clean rag
 
Tips
H. macrophylla, H. paniculata and V. macrocephalum snowball bushes respond to complete renewal -- cutting the shrub to the ground -- but may take more than one season to resume heavy blooming. Annabelles will bloom as usual if cut to the ground during winter.
Hydrangeas and viburnums will respond to heavy pruning by suckering -- sending up new branches. Cut these back when they appear if you want to limit the spread of your snowball bush.
Sterilize cutting tools with a 10 percent solution of household bleach and water or isopropyl (rubbing) alcohol before cutting branches and after finishing each plant.
 
 
Warning
Identify existing snowball bush shrubs before pruning and complete pruning at the correct time. In addition to being time-critical, annual pruning needs vary: For example, viburnum requires little regular pruning, while Annabelle stays tidy but productive only with annual renewal pruning.
predominantly on the upper part of the shrub. Cut from one to three of the oldest branches back to the ground to renew the shrub. You may cut up to one-third of the old stems from overgrown smooth-leaf hydrangeas to the ground to renew them. Renewal may affect the succeeding year’s bloom, so limit its use to overgrown plants or plants whose bloom has fallen off.
things You Will Need
◾Hand pruners
◾Pruning shears
◾Pruning saw
◾Bleach or rubbing alcohol
◾Mixing bowl and clean rag
 
 
Tips
H. macrophylla, H. paniculata and V. macrocephalum snowball bushes respond to complete renewal -- cutting the shrub to the ground -- but may take more than one season to resume heavy blooming. Annabelles will bloom as usual if cut to the ground during winter.
Hydrangeas and viburnums will respond to heavy pruning by suckering -- sending up new branches. Cut these back when they appear if you want to limit the spread of your snowball bush.
Sterilize cutting tools with a 10 percent solution of household bleach and water or isopropyl (rubbing) alcohol before cutting branches and after finishing each plant.
 
 
Warning
Identify existing snowball bush shrubs before pruning and complete pruning at the correct time. In addition to being time-critical, annual pruning needs vary: For example, viburnum requires little regular pruning, while Annabelle stays tidy but productive only with annual renewal pruning.
taken from http://homeguides.sfgate.com/prune-snowball-bushes-42978.html
Till next time this is Becky Litterer, Becky's Greenhouse, Dougherty Iowa