If they need to be watered that is the thing to do rather than cutting them off in the middle of the growing season. Watering that will prompt them to re-leaf, if not too far gone (dead or nearly so). Otherwise once established Spiraea japonica varieties such as this can be cut down to short stubs at the end of winter every year. As a basic maintenance procedure.

upstate NY???? .. you ought to know better to include lication ...

where embo lives.. it might be mid growing season.. for us in colder climes.. we are long over that hump.. and within 30 days.. we could have frost ...

i would NOT cut back hard now..... in my MI .. as i want the plants slowing down for fall and winter.. not all juiced up with a lot of fresh soft growth when the cold temps start ...

it probably doesnt matter... but why risk it.. on the other hand.. you could probably run them over with a truck.. and they will be fine next season.. they are spirea.. not really a foo foo plant... so do whatever you want...

ya know.. preWWW.. if i had two.. i would cut one back.. and not the other.... observe .... and learn ... the library just wasnt an option...

ken

If the plant lacks enough water to support all its growth, it will kill off stems and leaves. And probably a lot more efficiently than we can. I would leave the plants alone and let them cope with the drought. I would only give them water. Not cut anything off.