jm,

Yes you can but the timing would be off unless you have a separate zone for the Hydrangea irrigation. aloha

This is in a separate zone. So it should be good. I checked the websites for sprinkler systems and don't see accessories that attach to sprinkler systems. Any sources?

Look in Home Depot's drip system section. There are "octopus" converter heads ... unscrew sprinkler, screw on converter, add the distribution tubing and the emitter heads.

For more even watering, using several runs of emitter tubing to wet the ground evenly under the bushes would work.

You can cap all of the heads and add a drip system with products bought at home depot.

You can move the heads with a little effort using funny pipe.

How many heads are hiding under the plants?

Thanks for the advice. I have about 5 sprinkler heads and about 12 plants. 4 of them are not getting any water as when the plants get leaves they are blocking the path.