Pruning of hydrangeas depends on the type of hydrangea that one has and the time when you plan to prune; most old wood blooming cultivars typically have dormant spring 2024 flower buds by now. See this link for pictures to help identify yours if you do not know or do not have their plant labels:
https://plantaddicts.com/types... In general, pruning is optional (not a necessary task) but can be done depending on the type of hydrangea. That being said, if the plant has any leaf fungal issues or if the plant gets a lot of heavy, wet snow, consider doing deadheading –not the same as pruning- before the snow falls in order to minimize stem injuries or even trunk injuries for standard (tree form) hydrangeas of Big Leaf and Panicles.
Most species of hydrangeas produce lacecap form blooms but a few species also produce either mophead form blooms (Big Leaf Hydrangea, Mountain Hydrangea, Smooth Hydrangea, Rough Hydrangea) or panicle form blooms (Panicle and Oakleaf Hydrangeas). While some species of hydrangea only develop one type of bloom form, some species of hydrangeas can produce two types of bloom forms (but normally, on different varieties). Because you did not seem sure of the variety names of your hydrangeas, I included the most common lacecap and panicles in your area and probably gave you more information than necessary.
Cultivars of Big Leaf Hydrangeas (hydrangea macrophylla) and Mountain Hydrangeas (hydrangeas serratas) produce either mophead form blooms or lacecap form blooms. The flower buds for these develop depending on the variety. Most varieties produce only one flush of blooms per growing season from old wood; these develop dormant spring 2024 flower buds anywhere from July through September 2023. Because of that, they are best planted where they can attain the variety's estimated size at maturity and rarely pruned (you can prune leafless stems all the way down if they fail to leaf out by late June or in July). Newer varieties of these two hydrangeas can also produce two flushes of blooms, one in spring as described before and a second flush in late summer/fall 2023 from the new spring 2023 stem growth once these new stems reach a proper height to trigger bud set and immediate blooming. These too should rarely be pruned (you can prune leafless stems all the way down if they fail to leaf out by late June or in July). Rejuvenation pruning can be done to control the size of a very large specimen. You can also do major cuts during a short time when the shrub stops opening more new blooms and starts developing dormant flower buds a few weeks later, like azaleas and rhododendrons do; unfortunately, with our busy lives, it can be very difficult to notice when, in this short time frame, the shrub stops opening new blooms and if we prune "too late", we end up cutting off next year's blooms.
Cultivars of Rough Hydrangeas (hydrangea aspera) produce either mophead form blooms or lacecap form blooms. These hydrangeas develop dormant spring 2024 flower buds anywhere from July through September 2023. Because of that, they are best planted where they can attain the variety's estimated size at maturity and rarely pruned (you can prune leafless stems all the way down if they fail to leaf out by late June or in July). Rejuvenation pruning can be done to control the size of a very large specimen. You can also do major cuts during a short time when the shrub stops opening more new blooms and before the shrub starts developing dormant flower buds a few weeks later, like azaleas and rhododendrons do.
Cultivars of Smooth Hydrangeas (hydrangea arborescens) produce either mophead form blooms or lacecap form blooms too. The flower buds for this species of hydrangea develop starting in mid or late spring so, when pruning, they can be: left alone (not pruned), pruned now, once dormant or in late winter/very early spring (before leaf out). The only time when pruning is not recommended is around mid-to-late spring or summer, when they develop flower buds or when they are blooming. This species should not be pruned too much as the stems tend to flop; newer, thin, green stems flop more than older, woody stems do. This species benefits from staking of stems that are too thin.
Cultivars of Panicle Hydrangeas (hydrangea paniculata) typically produce panicle shaped blooms but a few varieties produce mophead form blooms. The flower buds for this species of hydrangea develop depending on the variety: either around July-September for Praecox; starting in mid/late spring or in the summer for most; in mid to late summer for Tardiva. Praecox blooms on old wood and should not be pruned now as it probably now has flower buds for spring 2024; instead, prune it during the brief period (a few weeks maybe) as it stops opening new blooms but before it starts developing dormant spring flower buds in the summer. Tardiva blooms on new wood but it starts blooming very late in the growing season so it may not be a good idea to prune this one now either, as it normally should still be opening flower buds now. Prune Tardiva once it goes dormant, in late winter/early spring or do not prune it. When pruning, the rest/majority of the panicles can now be: left alone (not pruned), pruned now, pruned once dormant or pruned in late winter/very early spring (before leaf out). The only time when pruning is not recommended for panicles is when they develop flower buds or when they are blooming. The stems of this species should not be pruned too much as the stems sometimes tend to flop greatly by the end of summer and their thin, new, green stems flop more than older, woody stems do. This species benefits greatly from staking (or pruning) of stems that are too thin, especially varieties that produce heavy, dense blooms. In order to develop future woody stems, try to cut no more than 1/3 of a green stem's length; in time, new green stems will turn from green to woody colors.
Cultivars of the hydrangea vines, aka, Climbing or Evergreen Hydrangea (hydrangea anomala, decumaria, hydrangea quelpartensis, schizophragma or hydrangea seamanii), also produce lacecap form blooms on old wood, should be cut seldomly (cut branches, not stems if practical). Branches with dormant buds should not be pruned now unless you need to stop or re-direct growth or if you need to remove leafless branches that do not leaf out as late as late June or in July. These vines/climbers develop dormant spring 2024 flower buds somewhere around July-September.
Cultivars of Oakleaf Hydrangea (hydrangea quercifolia) produce panicle form blooms. No cultivars should not be pruned now as they develop dormant spring 2024 flower buds from July-September depending on where one is located. Due to their structure, tall cultivars should have crossing/dead branches removed as opposed to pruning the whole stem down. Leafless shrub parts may leaf out quite late too sometimes so wait until the end of June or in July to prune. Compact varieties of Oakleaf Hydrangeas only require deadheading or let the blooms fall in spring or so.
Deadheading of spent/brown blooms can be done at any time of the year that you wish. Deadheading now, once dormant, or in late winter/early spring has no measurable effect on bloom production or winter protection. Deadheading, if done properly, does not affect future blooms even when done on any month of the year: cut above the first pair of leaves or if leafless, cut the string that attaches the bloom to the stem. Shrubs that produce lacecap form blooms will usually require little deadheading as these blooms tend to self-clean once the fertile flowers are pollinated (they do not remain attached to the stem as long as other bloom forms typically do).
