If they are really moles, those eat grubs and worms and not roots. The problem they cause cause in shrub beds is that they will tunnel under the rootballs and their network of tunnels can drain away needed water.

Voles aka meadow mice could be damaging to PJMs - what symptoms are you seeing that you suspect rodents?

I agree, it is probably voles. They tunnel under the mulch and eat the bark, girdling the plants. That is why you should never have the mulch touch the bark of the plants.

Another technique is to put hardware cloth around the plants when you plant our far enough so that it doesn't bother the roots and up our of the ground enough so they don't crawl over it.

I read that this Orange Crush Crown Imperial deters moles. I am not sure how true it is. I think it is pretty though.

There was a disturbed area in our yard when we bought this place (we've only been living here a couple of weeks)my husband said it was from a mole. It was heaps of dirt on top of the sod.

I messed up its digging area over a couple of days when it seemed as though the mole had tried to dig into the area again. I just turned over the soil there again. He appears to have left. If moles are like mice they do not like there areas to be repeatedly disturbed. And will seek more private area.

I bought one of the Crown Imperials for the garden just to see it bloom. Mole repelling will be a bonus if it works.

Here is a link that might be useful: Michigan bulb orange crush crown imperial