The Hydrangea Pruning Mistake That Will Result In Fewer Spring Blooms

Deadheading hydrangeas can be a somewhat tricky business because hydrangea varieties you have in your garden require different approaches to this task. If done improperly in autumn, deadheading some hydrangeas may result in fewer buds the following spring. This is particularly true for bigleaf hydrangeas (Hydrangea macrophylla) because certain varieties start forming new buds in late summer. If you have bigleaf hydrangeas, you should avoid deadheading in autumn and leave them intact until the following summer.

Bigleaf hydrangeas are versatile garden shrubs as long as they're grown in the appropriate zone. But some gardeners have issues with them blooming consistently. There can be various reasons for this, including cold temperatures, a lack of sunlight, and poor soil conditions. But one cause is that it's easy to unintentionally cut off small, newly forming buds while deadheading late in the season. Once cut off, these buds are lost and will not form again until after the next flowering season.

Sometimes there is confusion over pruning different hydrangea types. Panicle hydrangeas are generally much more cold hardy than bigleaf hydrangeas (for example, a 'Limelight' panicle hydrangea is hardy in USDA zones 3 to 9, while a 'Nikko Blue' bigleaf hydrangea is hardy in zones 6 to 9). This difference affects when buds form. Panicle hydrangeas go dormant in winter and start forming buds the following spring, whereas bigleaf hydrangeas start forming buds in late summer soon after flowering ends. Being able to deadhead panicle hydrangeas late in the season may make you think it's also a good time to deadhead bigleaf hydrangeas, when in fact the latter will be more vulnerable at that time because buds have begun to form.

Knowing what type of hydrangeas you have will help you know the best times for deadheading. These are bigleaf (Hydrangea macrophylla), panicle (Hydrangea paniculata), oakleaf (Hydrangea quercifolia), and climbing (Hydrangea anomala ssp. petiolaris). Oakleaf hydrangeas have big, textured leaves shaped like oak leaves. Climbing hydrangeas have woody stems with shaggy bark and may spread along the ground unless supported by a wall, fence, or trellis. It's important to know their growing zones to understand which hydrangeas can tolerate warmer climates or colder temperatures, as well as how these types of hydrangeas require different timing for deadheading.

Bigleaf and panicle hydrangeas are the shrubs most gardeners are familiar with. The bigleaf varieties include hydrangeas with pink or blue flowers in round flower heads that start blooming in late spring to early summer, including lacecap and mophead varieties. Popular varieties include the classic 'Nikko Blue,' or 'Blue Jangles,' or the 'Endless Summer' hybrids, including the cold-hardy 'Bloomstruck. Panicle hydrangeas have white flowers on cone-shaped flower heads, later developing green hues that turn rosy pink. Popular panicle varieties include 'Limelight,' 'Pinky Winky,' and 'Fire Light.' Panicle hydrangea flowers usually start fading by mid-autumn, and these flower heads can then be carefully snipped off in late winter. 

Bigleaf hydrangea flower petals are not quite as quick to fade. Some gardeners snip branches to preserve as dried flowers. This practice might cause you to inadvertently snip off buds, however, which might be somewhat small at this point. Leaving the flower heads intact will help you avoid accidentally snipping off any newly formed buds. If you can, prune your bigleaf hydrangeas in the month of August, after flowers fade but before the plant goes dormant.

You can deadhead faded flowers from your panicle hydrangeas any time in fall through the early spring. The flowers are usually at the very tip of the branch, and you can snip right where the flowers begin forming. Panicle hydrangeas form buds on new wood (new stem growth) starting in spring, so deadheading in the fall won't harm these buds. You can even prune them in early spring before buds form. Bigleaf hydrangeas, however, form buds on old wood, or existing stems from the previous year.

Bigleaf hydrangeas start forming buds around the beginning of August. Deadheading faded flowers should be done no later than August 1, and you still need to check for any new buds forming and be careful not to cut them. You may want to do some pruning in the fall; however the only part of your bigleaf hydrangeas you should prune in the fall are any dead or damaged branches. You might be tempted to trim branches to shape your shrub, but this is still best done in late summer to avoid disturbing any new flower buds that are forming. Getting to know the specific needs of your particular type of hydrangea shrub is important for giving it proper care and maintenance. Long-lived hydrangea shrubs do have some common issues to be aware of, but if grown in a suitable spot in your garden and properly cared for, they will reward you with years of beauty. Deadheading your bigleaf hydrangeas is a task best done in a very specific window of time, just as the flowers are fading and before the new flower buds begin to form.