1. Did I prune my hydrangea back fairly drastically in the fall or Winter?
2. Did my hydrangea leaf out early in the Spring during a warm spell and then get caught in a late Spring freeze?

THREE COMMON REASONS MOPHEAD HYDRANGEAS FAIL TO BLOOM:

1. A late Spring freeze arrives and ruins the developing bloom buds. The freeze may be light and even go unnoticed until one realizes that the blooms are not forming. Or it may kill all the emerging leaves, too. As a result, most of the new growth comes from the roots. When this occurs, you know you have a problem.
2. Most flower buds develop on the old stems. Once these stems are damaged in a late freeze, new flowers will not appear until the following year and only then if it is a milder Spring. (This is the rule for the vast majority of mopheads [macrophyllas] but there are exceptional hydrangeas that will bloom despite this damage)
3. Improper pruning. If you have pruned your hydrangea this year, you may want to check out the section on Pruning Hydrangeas to see if this could be the problem.
4. Planted in wrong zone. If you have had the bad luck to plant a hydrangea that has never bloomed after the first year, you may finally have to concede that this particular variety is not cold hardy in your area. Another variety may succeed famously, or you may have no luck with mophead hydrangeas. If your hydrangea has never bloomed, don't give up hope. You will be much more successful in growing hydrangeas if you purchase them from a local garden centre or nursery. Local nurseries try to stock hydrangeas that are known to do well in the area. It also helps to ask the nurseryman (it pays to shop where there is an expert!) if this particular hydrangea is temperamental to cold weather.