Answer: Some hydrangeas bloom on both old and new wood and others bloom only on new growth that is produced from old growth. So, the first question I have is are they the same types of hydrangeas as the one that blooms beautifully for you? If the leaf shape is different, you may have two different kinds of hydrangeas. Those that bloom on new shoots which develop on old wood will not bloom in your gardening region if all the old wood dies down to ground level in the wintertime. Another consideration is that hydrangeas bloom best with morning sunshine so make sure they are getting at least four hours of sunshine daily. Finally, too much nitrogen will promote lush, green growth, often at the expense of flowering. If the non-blooming shrubs are planted near a lawn, or somewhere else where you fertilize regularly, it could affect their flowering.
Hope this information helps you determine the cause for non-blooming!
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