I am finding that Terrene's remedy works better than castor oil alone, which I used last year, and both are better than nothing, though don't seem to totally get rid of the voles.

Here's the formula:
1 tablespoon castor oil and 1 cup human urine per gallon of water.

Thanks, Terrene, for sharing this.

My husband will be happy to hear of this "repellent" LOL and will want to know if straight urine does the trick also!

Hi guys, I just saw this thread. This isn't my repellent though, credit is due to the Hosta forum (can't remember exactly where I read it). Also learned about the 12.5% ammonia or vinegar solution for slugs on the Hosta forum (I can vouch that the ammonia works great). Apparently there are many critters and pests that love Hostas! I just love the fact that these solutions are 100% organic and cause no harm to the plants (and hopefully to beneficial critters).

The castor oil repellent saved many perennials and whatever few remaining bulbs in my front garden from certain demise. Saved the last 2 native Wild Hyacinth I started from seed, which take several years to bloom, from becoming vole food!!

I like to make it a little strong, maybe 1-2 TBS castor oil and 2 cups of urine in per gallon. I think the castor oil makes the roots and soil around the roots distasteful to the voles, it is very sticky and lasts for 2-3 months. Not sure what the urine does, perhaps the smell repels them also, if so male urine is likely stronger. Also it's a great nitrogen-rich fertilizer.

This post was edited by terrene on Fri, Sep 6, 13 at 5:52

PS. Remember to agitate well when applying, the castor oil is so sticky! I have one old watering can dedicated to this now, since the castor oil sticks to the inside of the can for several months, and I make sure not to use this one to fill the bird baths.

Thanks again for posting this solution,terrene!

I only treated the tunnels, no plants were involved. I used only urine(about 1 quart) then added several tbs of the castor oil (kept the solution stirred). This was poured along all tunnels leading into my perennial border. I repeated this the next day just to be sure!
It has continued to work!

I wonder if this would work on the ground hog tunnels.

I don't know about ground hogs, but that would be an interesting experiment, to pour some down a groundhog hole...

I sprinkle the solution all around the roots of the perennials I'm trying to protect. Not directly on the foliage, but in the root zones. I'm sure a little gets on the foliage, but either way it doesn't seem to bother the plants at all.

Terrene, are you still out there?