The wide array of hydrangeas available at garden centers reflects their popularity among gardeners who cherish the soft, full blooms and graceful foliage they bring to the summer landscape. However, at times, hydrangeas may disappoint by failing to bloom. Surprisingly, improper pruning often plays a significant role in this. It is crucial to recognize that not all hydrangeas are the same, as they belong to distinct pruning groups based on whether they bloom on old wood or new wood. Understanding this fundamental difference can demystify the process of pruning hydrangeas and ensure a profusion of blooms year after year.
The terms “old wood” and “new wood” refer to plants that produce flowers on the previous season’s growth or on the current season’s growth, respectively. Once you determine which pruning group your hydrangeas belong to and the appropriate time for pruning, caring for them becomes straightforward. This guide aims to elucidate the key disparities between old wood and new wood hydrangeas, highlight common species, and provide best practices for pruning each group.
Decoding Old Wood Hydrangeas
Hydrangea species that bloom on old wood develop flower buds on stems that grew in the previous growing season. These flower buds endure through winter on the branches and blossom in the following spring or summer. Pruning these older stems during the dormant period can inadvertently remove the flower buds, resulting in plants that do not bloom. Other factors that may inhibit flowering include browsing by deer and late spring frosts that harm these buds. While we may not control the weather beyond protecting our plants, adjustment of pruning techniques can stimulate blooming.
Many beloved hydrangeas fall into the old wood category, such as the popular bigleaf hydrangea (Hydrangea macrophylla). These Southern favorites boast large, glossy leaves and spectacular blooms that can change color based on soil acidity. They are typically divided into two main types: mopheads and lace-caps.
Another old wood species is the oakleaf hydrangea (H. quercifolia), recognized for its striking foliage and sizable cone-shaped flowers. Native to the woodlands of the Southeast, oakleaf hydrangeas exhibit vivid autumn hues and appealing peeling bark. Less common members of the old wood group include the mountain hydrangea (H. serrata), featuring delicate lacecap blossoms, and the aptly named climbing hydrangea (H. anomala).
For hydrangeas that bloom on old wood, the optimal time to prune is in the summer after the flowering cycle is complete. Generally, old wood hydrangeas necessitate minimal pruning. If desired, lightly trim oakleaf, climbing, and mountain hydrangeas to maintain their shape post-flowering. Simply cut back branches to a healthy bud and address any crossing or rubbing stems. Climbing hydrangeas, known for their vigorous growth, may require more significant pruning to
Understanding New Wood Hydrangeas
Hydrangeas that bloom on new wood have young, tender stems that produce flower buds in spring. These buds bloom in summer, making them less vulnerable to frost damage in winter. Panicle hydrangea and smooth hydrangea are popular new wood species. Panicle hydrangeas thrive in hot, humid climates and are known for their large, white or green blooms that turn pink or burgundy. Smooth hydrangeas, often mistaken for ‘Annabelle’, produce massive flower heads up to a foot in diameter in white, pink, or green. Pruning new wood hydrangeas in late winter or early spring can help manage plant size and promote strong stems and large flowerheads. Scaffold pruning is a useful technique to support new growth.
Comparative Analysis: Old Wood Vs. New Wood Hydrangeas
Old wood hydrangeas, such as bigleaf and oakleaf varieties, flower earlier in the year as they develop buds in the previous season. Pruning should be done after flowering to avoid removing potential blooms. New wood hydrangeas, like panicle and smooth types, produce buds on new growth in spring and flower in mid to late summer. These hydrangeas can be pruned during the dormant season without affecting flower production. Consider the flowering habits and pruning needs when choosing between old wood and new wood hydrangeas for your landscape. Each type has its advantages and considerations in terms of flower colors, bloom times, and pruning requirements.
Consider key characteristics when choosing hydrangeas for your garden. While many people are drawn to flower color when picking plants, it’s important to note that soil pH can affect blossom color in certain hydrangea varieties. Additionally, water and light requirements can differ among species. To achieve the best results, it is advisable to select plants that suit the existing site conditions rather than attempting to modify the planting area to accommodate a specific species. For more information, be sure to check out the original article on Southern Living titled “8 Mistakes You Should Never Make With Your Hydrangeas.”
