From late June and beyond, it’s high time for hydrangeas! By then, your plants – in a normal year – should be flowering. Are yours showing their traditional big blue flowers this year like the one in this photo? Maybe yes, maybe no? Why is that?
There are two main reasons big leaf hydrangeas (macrophyllas) don’t flower: one can be attributed to us, the gardeners – what we do. Gardeners have been known to prune at the wrong time and cut the flower buds off these plants. Your best bet is not to prune big leaf hydrangeas at all. They usually don’t need it. Gardeners might also be fertilizing this plant improperly. If it gets too much nitrogen, it will makes leaves and not flowers, especially if it sits adjacent to a lawn that gets fertilized. Rose fertilizer is an excellent amendment as is compost like Coast of Maine Lobster compost. The other thing we do is give it too much water when it looks wilted. The best thing to do when that happens is to walk away and wait until the sun is off the plant to give it time to re-hydrate. (Usually it recovers and pulls moisture back in) When a big leaf hydrangea gets too much water, it will make leaves and not flowers.
The second reason big leaf hydrangeas don’t bloom is the weather. Cold temperatures before the plant hardens off,(deep winter cold, early cold snaps and the like) kill the flower buds that get set after August 1. Those buds need to make it through to bloom time so you can get the flowers you enjoy so much. It’s a dangerous and tricky destiny for them as Mother Nature throws all kinds of obstacles in their way. As gardeners you can insulate your plant in a wire cage stuffed with leaves or erect a screen to protect them from icy winter winds. Plants that are protected by some kind of persistent winter foliage from Alberta spruces, rhododendrons, junipers, oaks, beeches, etc. do well. Another kind of protection can come from sheds, houses, fences, and other structures.
The last way you can have better luck getting hydrangea flowers is to choose plants that give you better odds. The plants that do that are hydrangeas that are known to rebloom. Those are plants that even if the winter buds get killed off, will generate new buds during the growing season, that will actually flower during the summer those new buds are created. (That way you get flowers before the season closes) Your garden center can direct you to which ones they have that do that. The second way you can increase your odds of getting flowers is to buy hydrangeas with “serrata” in their name. These are hydrangeas that originate from the mountains of Japan and are more hardy and accustomed to cold temperatures. Oakleaf hydrangeas are also more reliable bloomers and perform better in years when bigleaf hydrangeas don’t. They also have very interesting foliage that turns a wine red color as the temperatures cool off. And of course, you can select hydrangeas that bloom on current year’s growth like Incrediball® Blush Hydrangea arborescens or Fire Light® Hydrangea paniculata They are truly foolproof! No amount of deer browse, pruning, and cold temperatures will get in the way of them producing spectacular flowers each season.
All you have to do is choose the ones you want.