I live in Western PA, zone 5/6. I was told to pruned Hydrangeas in the spring back to 6-8" from the ground. That they only bloom on old wood. It seems to me that if you do this, any growth that year would be new wood and no blooms. This seems to have happened to my bush. It's about
2 1/2' tall, 3' in diameter, great foliage, but no blooms. When should it be pruned?Try this web
Different species of hydrangeas have different criteria for pruning. Some need very little pruning at all, other than to shape, as with H. quercifolia & H. anomala petiolaris. H. arborescens does well with the dramatic pruning you describe. Pruning of H. paniculata would depend on if you were training it to be upright like a tree or as a broad shrub, & need not be dramatic pruning, just barely enough to induce new growth on which flowers occur, though in your zone a more dramatic pruning might be needed because of winter damage. Most hydrangeas prefer late winter pruning, but H. macrophylla is better done in late summer when flowers are getting scruffy & new shoots are developing; it needs a heart of old wood to always to be preserved since it will bloom on shoots from the old wood; late winter or spring pruning would remove buds, & in your zone as the buds would probably freeze off.
If your instructions for yours was correct you must have H. arborescens, & in your zone it suffers a lot of winter injury so it is recommended to prune it to under a foot height in late winter or very early spring (such a complete cut-back wouldn't be necessary where I live). It flowers on NEW growth, & if yours failed to flower, probably not from degree of pruning, unless you did it after new spring growth had started, in which case you cut off the buds. It's not unusual that hydrangeas do not to bloom when very young & newly planted as they expend most energy on developing roots & settling in. Or with too much sun wit&h too little summer watering, buds might bake so never develop. Though they like very bright shade or dappled sunlight, too deep a shade will keep them from blooming. Or if you fertilized the hell out of it, it'll be annoyed; it will get bushy without flowers if over fertilized.
Someone else with more hydrangeas than I grow may have better advice, but it'd help to know if it really is H. aborescens you're asking about, because it makes a big difference.
-paghat the ratgirl
Paghat's information is very good. Pruning hydrangeas of any type is never a "requirement" and many are best just left alone to grow and flower at will, however your climate and the specific type of hydrangea will be a big factor in how well they do this. Both paniculata and arborescens bloom on new wood and in colder climates, often act more like a herbaceous perennial rather than a shrub - they can die back to the roots in winter but will regrow and bloom the following summer. Removing the dead wood should be done in spring as you see new growth developing.
Bigleaf hydrangeas (H. macrophylla) are marginally hardy in zone 6 and typically not hardy in zone 5 without winter protection. These do bloom on new wood and the new growth that developed this season must be protected from freezing in order to enjoy any flowering. A google search will turn up any number of sites that can give you specifics on how best to accomplish this. I don't generally recommend that you prune these at all except to remove old flowerheads or dead wood, unless they become excessively leggy. Then you can cut back selected branches/stems with the understanding that the cut stems will not produce flowers for that season.
There a couple of new macrophyllas on the market that have been developed for exceptional cold hardiness and the ability to bloom on both new AND old wood. Look for 'Endless Summer' or 'All Summer Beauty" - they are reputed to be hardy to zone 4.
pam - gardengal
Whoops, sorry - that should be Hydrangea macrophylla or big leaf hydrangea bloom on OLD wood. :-))
pam
Endless Summer Hydrangeas require pruning to keep blooming more profusely......
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