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I’ve been hosting a radio program on KDKA Radio in Pittsburgh for ten years, and the most common question my co-host and I are asked on-air is “Why doesn’t my hydrangea bloom?”
Upon further inquiry, we always come to learn the caller is asking about a big-leaf hydrangea, Hydrangea macrophylla. While these old-fashioned hydrangeas bear gorgeous balls of pink or blue flowers, they’re notorious for their unreliably here in the northern U.S. Some years they bloom beautifully, while other years there’s not a single bud in sight. If you’re a USDA zone 5 or 6 gardener who has faced this experience yourself, here are a few tips you can use right now to get better blooms from your hydrangea.
1. With few exceptions, Hydrangea macrophylla varieties (like the double-flowered cultivar ‘Paraplu’ featured in the main photo of this post) form their flower buds on old-wood. This means that next year’s flowers are already formed inside the buds of those seemingly dead sticks. If you prune off any branches now – or in the spring – you’re cutting off future flowers. My radio co-host and I like to tell our callers that the best pruning technique for big-leaf hydrangeas is no pruning at all.
2. The dormant flower buds housed inside those brown sticks are prone to damage from cold temperatures and drying winds. Of particular harm are the late-spring freezes that occasionally occur. To protect your hydrangea’s dormant buds, surround the plant with a layer of protection. Hammer four 1″x1″ hardwood stakes around each plant, and use a staple gun to attach a perimeter of burlap or black landscape fabric to the posts. Make sure the fencing is as tall as the shrub itself. Do not cover the top; the weight of any accumulated snow can send the whole thing toppling down on top of your plant. Leave this protective fortress in place until late spring, when the hydrangea’s buds start to swell.
3. Big-leaf hydrangeas tend to perform better when located in a more sheltered spot. If possible, relocate any non-blooming specimens to a nook that’s protected from high winds and located near a heat-absorbing wall or driveway. Hydrangeas are best moved in the early spring, before the foliage emerges, or in the autumn, a few months before the ground freezes.
4. For more reliable bloom production, you may want to consider adding a few different types of hydrangeas to your landscape. Hydrangea arborescent is a slightly hardier species that produces massive, white, snowball-like flower clusters. ‘Annabelle’ is my favorite cultivar. H. quercifolia, the oak-leaf hydrangea, is another uber-reliable bloomer with a stunning fall color and white conical blooms. There are, however, a few H. macrophylla cultivars currently on the market that have been selected to produce blooms on both old- and new-wood. I’ve had the most success with a newer introduction called ‘BloomStruck’.
Tell us about your favorite hydrangea and how you help protect it for the winter.