If the blooms are pink or blue, they're macrophylla's. If they're white, they're not macrophylla's. Macrophylla's bloom off of stems that survived the winter. If the stems die, no blooms. The white blooming ones are much more reliable bloomers.

Macs can be winter protected by covering in leaves to help the stems survive the winter. in WI, keeping them alive is likely challenging.

If you post pictures we can try to help you figure out what kind. Judging by the age, you likely have hydrangea macrophylla, that bloom on old wood, where the buds are likely killed in zone 5 winters.

Search 'hydrangea care' on Google and your top 5-10 results should tell you everything you need to know about how to prune to encourage branching and winter protection methods. If you're a person who likes to simply leave your plants alone, hydrangea macrophylla shrubs might not be the right ones for you.

The general theme is to encourage as many shoots and branches as possible to set as many buds as possible within a 2-3' radius from the crown. That way, come December, if you mound leaves, hay, or place a custom shrub enclosure on the plant you should be able to get blooms next season. Come late April or early May, you may remove insulation and apply rounds 10-10-10 fertilizer in May and July 1 to encourage blooms and health.

I agree that the old, nonbloomers are most likely old wood-budding macs getting zapped by winter cold. And the one that IS blooming very likely one of the newer remontant types that bloom on both old AND new wood/growth.

And just so you know, there are plenty of white blooming macrophyllas :-) I think what was meant by that comment was that other types of hydrangeas - paniculatas and arborescens, which produce only white flowers - are both very cold hardy and bloom on new growth, so blooming is unaffected by winter cold.