Hello from Texas Melanie. Well, pruning or too much fertilizing could have done it.

Hydrangea macrophylla, the one that I am guessing that you have, produces blooms shaped like mopheads or lacecaps. A lot of these Macs will develop flower buds only once, in July-August in my area. The flower buds are invisible at first and will open much later... in April-May here.

So, I think that the owner pruned the plants hard after flower buds had formed so now you are not getting any blooms. Provided that you do not prune again after flower buds formed, the problem should not reoccur next year.

Although old hydrangeas can benefit from some pruning every 7-10 years, pruning is generally not needed if the shrubs are growing in a location where they can reach their mature size. If I need to prune for some reason, I prune here after the plant has bloomed but before July.

Deadheading -not the same as pruning- can be done at any time of the year. See the link below.

Feeding hydrangeas too much nitrogen-rich fertilizer (for example: blood meal, some liquid fertilizers, etc) can make the plants concentrate on growing nice leaves at the expense of blooms. How to tell if the soil has too much nitrogen? Well, luckily, there are plant nurseries that sell low priced soil analyzing kits to determine if the soil has too much nitrogen. You get a test tube, add some soil, a pill that came with the kit and water. Shake, wait a while and the instructions will say what color means what.

I fertilize my hydrangeas with either cottonseed meal, compost or composted manure.. about 1 cup per year in Spring. You can also use a general-purpose slow-release chemical fertilizer (follow the label's directions).

During the growing season, you can also use/sprinkle coffee grounds, liquid seaweed or liquid fish. But all this feeding stops around July in my area in order to make sure that the plants will go dormant when Fall arrives.

Does that help you, Melanie?
Luis

Here is a link that might be useful: Pruning hydrangeas

You have been given very good information. Every few years the macs will have gotten so overgrown they will need to be cut back pretty drastically. Doing so will sacrifice next years bloom, and I accept that. Here in the Mediterranean climate of the north coast of California, I never need to fertilize, only maintain a regular mulch of vegetative matter. The plant will outgrow its space soon enough and fertilizer will make it sooner. Al