Why don't my hydranges bloom?

Question:

Answers:
There are many reason for a hydrangea to fail to bloom. I will start with the most common reasons and go from there.

I have found that the most common reason for lack of blooms is pruning at the wrong time during the season and eliminating the flower buds. My advice is to not prune your hydrangeas other than simple removal of spent flowers which will be pruned off just below the flower itself at the next lower set of buds. You may prune the tops of your hydrangeas after the active growth begins in spring and it is obvious what is dead and what is not. Be careful because even now I am still speculating that certain buds are dead only to notice a few weeks later that the bud I thought was dead is now a stem in active growth. Remember that paniculatas and arborescens can be pruned as they flower off of new growth. There are also some varieties of macrophylla that bloom off of new wood and can be pruned in late season. Those varieties are 'All Summer Beauty', 'Penny Mac' and 'Endless Summer'. It is these hydrangeas that are confusing everybody as to what, when and where to prune or not prune. Don't put yourself in a situation where you are forced to prune. Be patient in the spring and wait for all buds to return before pruning the tips.
Too cold of a climate for successful hydrangea flowering. If you are in zone 5 you will not have luck with 95% of the available mopheads on the market. If your neighbors do not have hydrangeas, other than pee gees or annabelles, you are more than likely in too cold of an area for successful bud return. What confuses things is that the climate seems to be changing and zone lines may shift from year to year. We also are experiencing el nino every 7 years or so and this is causing variations in our winters from mild one year to severe the next year. While the hydrangeas will grow like crazy and give you lots of great foliage, the buds will always burn in a normal zone 5 winter.
Planted in heavy shade. Too much shade can be a cause of non flowering simply because of the lack of energy from the sun. You will notice less flowers gradually as the years go on. Transplant to a sunnier location.
Severe dry spells the season before can and does cause the hydrange to not flower. This can be avoided by choosing a location that is not too sunny and by adding some sort of irrigation system.

While some soils can be so poor as to cause growth and flowering problems, the above 4 reasons are the main causes of a non flowering hydrangea.