Yes, you can cut them back hard to renew them - established azaleas will recover from being pruned back quite low, as low as 6-12". You might want to replace the rock with a mulch of something organic, will conserve the moisture they need and cool the root zone so summer heat and dryness doesn't stress them while they are putting out new growth.

Thank you. So far, I have pruned back 2 of the 4 - I was wrong, the one furthest back appears to be a spirea. So I have 2 questions if y'all dont mind.

I found a bunch of babies - they have layered themselves over the years. When can I dig them and what is the best care to grow them into a nice specimen?

Second question..can I hard prune the spirea way back?

Thanks for your help!

In my cooler summer climate, I wouldn't hesitate to cut the rooted stems and move the self-layered plants now, but you might find they require less attention if you wait until Fall. Plant no deeper than they were originally growing, in humus rich (high in organic content) soil.

Spirea are a little more complicated, but if you dont know what you have, also pretty forgiving so I would say prune as you must to get it under control :) There are spring blooming types that should be pruned right after blooming, summer blooming types and of the summer blooming, those that bloom on old wood and those that bloom on current years wood, so one simple answer doen't cover all spirea.

Dina, the type of pruning you're asking about and mor8 has recommended has a name. 'Rejuvenation pruning' is an accepted practice for situations just like yours. Just be sure to cut them back to a foot or less.

I cut all 10 of my bridalwreath spirea's to the ground and they came back fully in 2 years. They looked like crap prior, now they look great. Of course when the neighbors saw what I did they thought I went mad.