Hydrangeas were not "designed" to be divided. However, a lot of people have done that with old specimens. Do a forum search for keywords like "divide".

I would consider rejuvenation, i.e., pruning them in thirds for three years (the tallest 1/3 stems on year one; the next tallest stems on year two; and the rest of year three). When pruning the stems, prune the stems all the way to the ground which will force new stems to eventually grow.

You could also transplant the two closest to the steps elsewhere but then you would need to "fill" the space with something. The new plant could be another type of plant or yet another hydrangea, just choose one that does not grow as tall; investigate hydrangea serratas or some macrophyllas that won't get too big.

You could also extend the steps to the sides into the area that was "vacated" by the hydrangeas that you transplanted but, ouch, that would be more expensive.

This post was edited by luis_pr on Sun, Jan 19, 14 at 2:53

Plants are divided to get free new plants. It's not to keep growth in check. The divided hydrangea will just grow back to it's old size.

If they're too big, you have to dig them up and replace them with something smaller or dig them up and move them away from the house.