04 August 2012

Protecting foliage plants against herbivores

Those who farm or garden in rural areas or at the edges of suburbia know the challenges of deterring predation by rabbits and deer, a situation made worse this year by widespread drought diminishing wild sources of food.

We use fencing to protect some of the flower beds and part of the vegetable garden, but that's not practical (or visually acceptable) in a woodland garden.  In that setting, the traditional control methods are usually repellants rather than barriers.  Some success has been claimed for tucking human hair swept from barbershop floors into the base of plants; commercial products include wolf/lion/etc urine and other irritants, most notably capsaicin (the active ingredient in hot pepper).  I've had a modicum of success placing mothballs near plants when they emerge (but that doesn't seem to protect the upper leaves).  The problem with virtually all repellants is that they have to be recurrently applied, since they are not weatherproof and may wash off the leaves after rain.

When I was in the woods today, I found it interesting that the rabbits are just devouring the stems, leaving the leaves scattered nearby.  Perhaps the hosta tries to concentrate some intrinsic repellant in its leaves, but I think more likely is that the water content of the leaves is very small during our drought, and higher in the stems.

This week while driving I heard on the radio the tail end of comments by a Wisconsin wildlife biologist on this topic.  Of greatest interest to me was a description of a new product that was approved last year and is now on the market.  Repellex is a "systemic" capsaicinoid that is absorbed into the leaves of the plants. I found some details in the Blog of an Ancient Gardener:
The tablets protect ornamental plants from these browsing animals: deer, rabbits, voles, moles, gophers, groundhogs, feral hogs, dogs, and cats... “Water dissolves this product in soil, where it is absorbed by roots and moves up through the plant. Once absorbed, rain or watering cannot wash off this internal protection. Even new growth is protected against animal browsing for the entire growing season."

Application: “Place tablets in soil or growing medium of plant. Position 2-3 inches away from root crown, and push 1-3 inches below the soil surface. When more than one tablet is applied at once, evenly space them around the plant. Activate the application with irrigation or natural rainfall. Do not over water. For containerized plants, use enough water to wet the potting soil thoroughly without causing water to flush out from the bottom of the container.”

Application rate is based on the sum of the height and width of a plant. A plant that’s 3-feet wide and 3-feet tall would need six tablets. The label explains that fast-growing plants may need more than one application per year.

Cost: The company website currently lists several size bottles of tablets (30, 150, 300). Prices range from 40¢ a tablet in the smallest bottle to 33.3¢ a tablet in the larger sizes...
Multiple tablets per plant makes this product rather expensive, but it certainly would be worthwhile for selected plants.  It obviously cannot be used in the vegetable garden.

I'm curious whether any readers with horticultural backgrounds have comments, and whether any of you have actually used this product.


  1. It obviously cannot be used in the vegetable garden.

    I dunno... pre-spiced tomatoes for my spaghetti sauce sounds pretty good!

    I will send this link to my friend who fights a losing battle with the deer every year, trying to save her tulips. Will let you know if she has used the product.

  2. My family used to have a pet house rabbit. It would occasionally start gnawing on wooden furniture* particularly the kitchen table. To discourage this behaviour my mom spread some hot chilli paste on the table legs where he was gnawing. To be fair, this did work as he stopped gnawing and instead sat there licking the chilli paste off, before going for a drink of water, and then returning to the table to lick some more and then eventually going for a lie down, panting heavily.

    In other words - I doubt that a slight pepper flavour would discourage any seriously hungry rabbit.

    *We didn't realise until later that he was gnawing to grind his teeth down, and he would gladly gnaw on some small fresh tree branches which probably tasted better to him than a piece of furniture.

  3. The problem is that nobody asked or told the deer and rabbits that their home was being converted into a human house + garden. They consider it a great idea that someone plants delicious stuff in their habitat.

  4. My husband mixes up a water/hot sauce/chili pepper solution and sprinkles it on our leafy garden greens in the early summer. It seems to work. I guess they try it once and don't come back.

  5. I will keep this in mind, thank you for posting :) We had bunny problems at the beginning of the year, very frustrating - deceptively smart animals!!! I use a stinky coleus plant to repel them (sometimes more successful than others) but it's a bit repellent to humans, as well (I don't mind it, but my husband does. Must be why he never weeds...) A dog grooming friend donated some clippings to me, but the bunnies have departed for now, so I'm going to have to try that next year and see if it works.


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