Castor oil-best application method and cautions

by Beatrice
(Beverly, MA)

What is the best method for applying castor oil? I have a brand new hand pump style deck sprayer I intended to use in the garden (wasn't sure what for, but this could be the first use!)-would this work? I don't have moles or voles, but plenty of squirrels. If the oil may help keep the little buggers from digging in my lawn and flower beds I'm willing to try it. Are there any specific place to avoid, such as new tender growth like just emerging tulips, hosta tips, etc.


Doug says that if you're going to be using it as a "fragrance" style deterrent, then you want to use a fine nozzle type of sprayer (not sure what a deck-sprayer is) that will put a mist out. I'm also not aware of any plants this product burns but I suggest you read the label on this - that normally tells you any specifics.

I do know that some grades of castor oil will get your skin tingling and you really don't want to spray this product (or any other for that matter) around an open flame (it's oil and flammable).

If you're concerned at all - I have two suggestions. The first is to make sure you're using the oil at the right concentration so make sure your mixing is right.

Secondly - spray a few test plants and then wait 24 hours. See if the plants are "burned". I'd also suggest being *very* careful around plants such as blue spruce as they can be really damaged by horticultural oil sprays (remember castor oil is oil). I do not know if it burns spruce as well but it certainly isn't something I'd want to experiment on with valuable evergreens.

So bottom line - read the label. Treat it as a horticultural oil and test small parts of any valuable plant before spraying.

Hope that helps.