We have received a few inquiries about hydrangea not blooming and stem dieback so far this year. We suspect last winter's fluctuating temperatures (very mild spells followed closely by a sharp drop to cold temps.), which occurred several times that season, caused stress to plants and probably the death of some stem tissue and/or the dormant buds on them. Flower buds tend to be more cold-sensitive than leaf buds, but at some point they can all succumb. If we were behind on precipitation at the time, that can exacerbate any vulnerabilities.

Bigleaf Hydrangeas contract several fungal and bacterial leaf infections fairly regularly, though they tend to be more of an eyesore than a serious threat to long-term plant health. (We do not suspect they are related to stem dieback or not blooming ) If you notice this now or in the future, the worst of the spotted or burnt-edged leaves can be clipped off but otherwise no action needs to be taken. A fungicide would not offer complete protection nor could it cure existing infection. Watering at the base of the plants when it is needed is best so the leaves don't get too wet.

Anecdotally, we've heard from regional nursery wholesale growers that reblooming hydrangea varieties like 'Endless Summer' can stall-out and not rebloom well on the new growth if the overnight temperatures remain warm. Since this is a common occurrence in the mid-Atlantic, the plants might produce a decent later flush of blooms on the new growth, but only once the evening temps stay more mild. We've seen reblooming hydrangeas still carry fresh flowers well into autumn. We realize you said they haven't bloomed well at all recently, but maybe a slight difference in weather (if patterns don't repeat themselves) will result in better recovery this year.

Generally, established shrubs should not need fertilizer, and any fertilization should ideally be based on the results of a laboratory soil test to check for deficiencies, but a modest dose (as per package label directions) of a general-purpose and slow-release fertilizer might not hurt to try to spur the development of new growth and flower buds.

If the shrubs are receiving progressively more shade from any nearby trees that have grown since the hydrangea were planted, perhaps they are no longer getting enough direct sun to flower well. We would expect this to be a gradual instead of a sudden change, but while Bigleaf Hydrangeas do appreciate some shade during our hottest afternoon hours, we find they tend to bloom to their fullest potential if receiving a few hours of sun in summer.

Lastly, are you pruning and when? If you prune the bigleaf varieties in the late summer, you could be pruning off the following springs blooms and could be another factor that is resulting in no blooms this year. Guide to Pruning Hydrangeas

Let us know if you have further questions and hopefully we can guide you to having beautiful blooming hydrangeas again!

Emily

Emily:  Thank you for the prompt reply and useful information.  

You're welcome