I made an habenero sauce to keep deer from eating certain plants. Dried habenoros blended with water. I'm not convinced it is that effective on deer because of all the rain we get. However, my dog smelled it and started rolling in it. She loved the habenero sauce. This was about 4 hours after I applied it and no rain to weaken it.
I agree with aquarose. A fence should work. You could try training but I've found that training requires constant reinforcment.
I never agree with my dog about gardening either. I lay chicken wire around on the ground near things he damages regularly. Sometimes it keeps him away since he does not like the feel on his paws. I have also put tomato cages around things until they are big enough to handle more abuse.
Unfortunately, most of my pretty and fragile things are now in the front yard.
weird-my chickens don't bother my irises at all-I did however plant some Bishops weed too close and 3yrs later am regretting it big time-it's killed some of my iris.
I've bought a bunch of new iris from Brecks Holland last fall-they're coming up-I'd hate to lose them...