It’s a common problem. You anticipate those amazing hydrangea flowers, only to be disappointed with a leafy green shrub that refuses to bloom. If you have a hydrangea that’s not blooming, there could be a few different things causing it. Here are some tips to help you figure out why it’s withholding beautiful flowers from you.
One of the most common reasons for hydrangeas not blooming is pruning mistakes. When and if you should prune depends on what kind of hydrangea you have. Some bloom on old wood, last year’s growth, and some bloom on new growth that comes in new this year.
Hydrangeas that bloom on old wood start to create their flower buds for next year as soon as they finish blooming. Therefore, pruning those types can mean you’ll risk taking off flower buds for next summer. In general, hydrangeas that bloom on old wood don’t require much pruning, except to remove deadwood or control the shape and size of the plant. If you do need to prune an old-wood hydrangea, know you may have fewer blooms the following season, but it should be back to normal the year after that.
Hydrangeas that bloom on new wood can be safely pruned in late fall or early spring while the plants are dormant. If you like the look of their dried flowers, you can leave them all winter and prune them off in spring. When you do decide to prune, never take off more than 30% of the plant’s total volume.
Some hydrangeas are reblooming types—they will say this on the label when you buy them. It’s almost impossible to find a time to prune them where you won’t have to sacrifice some buds or blooms, so be aware of that. Similar to old wood bloomers, reblooming varieties really should not need much pruning, so remove deadwood only if required. Essentially, we suggest you plant your hydrangea in a large enough space to accommodate its future size, allowing you to avoid pruning unless absolutely necessary. Here are a few varieties that bloom on old wood, and some that bloom on new wood, to simplify your pruning schedule:
Hydrangeas That Bloom on Old Wood
Hydrangeas That Bloom On New Wood
Hydrangeas may need fertilizer, but using a fertilizer with a high nitrogen value (the first number in the NPK sequence) will encourage lots of leaf development at the expense of flowers. You can add bone meal when planting or choose a higher phosphate fertilizer (the second number in the NPK sequence) to encourage more blooming. We recommend you use a fertilizer specific to hydrangeas.
Frozen Flower Buds
If you have hydrangeas that bloom on old wood, and you had a late spring with some late hard frosts, your flower buds may have suffered cold damage which will stop them from budding this year. There’s not much you can do about this if it happens. However, you can prevent it in the future. First of all, make sure the hydrangeas you’ve planted are hardy enough for our growing zone. You can also wrap them for the winter, similar to how you’d wrap a young evergreen.
Wrapping will keep your hydrangea safe from cold damage, but over the winter, the fabric rubbing can damage buds right at the end of the branches, so those buds may not bloom for you. You could also build a frame around your hydrangea, with chicken wire and stakes, and then line it with cardboard or another wind-blocking material, and wrap the whole cage in fabric or burlap. This should prevent the buds from being rubbed off. If you’re expecting a late spring frost after you’ve already removed the wrapping, it’s not a bad idea to wrap them up again overnight.
Too Much or Not Enough Sun
The planting location for your hydrangea can also affect its ability to bloom. Not all hydrangeas love the same growing conditions. It can get complex, so know your specific variety and the conditions it prefers. With some varieties, if they don’t get enough light, then they will only produce leaves. While if other varieties get too much direct sun, the leaves and buds may get sunburn and not bloom. Ideally, locate your hydrangea where it can get the recommended amount of sunlight for its specific variety.
Still have questions? Confused about which hydrangea is right for your landscape? Come visit us at our Quad Cities garden center; we’ve got everything you need to help your hydrangeas bloom and thrive!