I have voles but they do not eat my iris. They will eat thinks like crocus, however. I *believe* moles are insect eaters but not sure.
But that really doesn't solve your problem. I can only tell you how they act here in NJ.
If I were you I would see if neighbors have problems with voles eating iris; if there are no neighbors with iris, i would probably put some in the ground (the least precious) and see how it goes.
Laetitia

they will devour you... i am in the same situation as in never wanting to kill anything. what i did that worked for 2 years only was lay chicken wire down then dirt on top. i did it for like 3000sf. but by year 3 i think they ate thru...

I'm one of the biggest animal lovers there is. I tried to kill a mole about 5 years ago. I injured the poor thing and my son had to finish the job for me. I cried for days! Now that said, niether voles or moles eat my iris. Moles eat grubs(white half moon shaped worms you find when you dig. Voles on the other hand eat plants. Voles live in the tunnels that Moles make while searching for grubs. I don't like to poision for the grubs cause it kills my good worms and I just plain don't like using chemicals unless it's a last resort.
So my special helper is a cat. My dear cat usually kills about 25 - 40 moles and voles a year. He loves to hunt these things. He has compeletly lost his bird hunting instints(sp?) and is always looking for voles and other rodents, which he seems to find plenty of each. I have been given a nice present of a field rat on more than one occasion, in the house!

I grow castor beans by the dozens and have seen mole tunnels right next to the big fat roots of the beans. So this doesn't work for me. If you can't have a cat, I'm not sure what to tell you.

Good luck! May God bless you each and everyone with his loving Grace, Mona

Voles will eat your irises. The yr we fought them, my husband finally made a mixture of hot liquids and spices. We placed this in every hole and around all the irises that the voles were munching on. We then smashed all the runs down and tilled the garden. Applying a little more hot around the irises. I haven't been bothered with them since.
Of course since I am typing this out, I will find voles eating on them tomorrow.

I have eight outdoor cats and they keep things well under control here!

Nancy

Thus far (Knock on wood) the moles/voles have not eaten my iris. The majority of mine are the older-passed-along type. Now that I have said this I hope I don't go out tomorrow and find evidence that they do in fact eat them! I have had my iris for approx. 30 years.
Good luck!

Voles killed one of my iris, and have gnawed on a couple of others; however in my garden they seem to prefer other things, especially baptisia. I have two cats who hunt so that helps. If you do have a problem my first thought was chicken wire too, and some sharp-edged gravel next to the rhizomes. Here in the East one species tunnels and feeds on the roots from below, and another feeds at the surface.