The Wildlife-Friendly Vegetable Gardener (Storey, 2014), by Tammi Hartung discusses methods both to promote wildlife in your area and to repel them from your food-garden. Hartung is a certified organic grower, focusing on native, herbal, medicinal, and rare plants. She is also the author of Homegrown Herbs. The following excerpt talks about wildlife repellents to use in your organic garden.
Repellents: Smelly Stuff and Hot Stuff
Short of a physical barrier, the best way we’ve found for discouraging persistent problematic wildlife is some type of repelling agent. We use many that we make ourselves, and we purchase others that we’ve found to be effective. I classify repellents into two groups: those that taste or smell disagreeable or otherwise irritate, and those that give a false message to the targeted wild animal that a predator or dead animal is nearby.
No matter what type of repellent you choose, keep in mind that most will have to be refreshed regularly, at the very least following any rainstorm. Others can last for up to six months and still maintain their effectiveness despite the rain. Some commercial products that would normally be odiferous to our human noses are deodorized but still maintain their ability to repel wild or domestic animals, whose sense of smell is much more sensitive than ours. Because most birds have no sense of smell, and since they often tolerate eating very spicy plants, repellents typically do not work well for birds.
In especially challenging circumstances, we’ve learned to combine repellents with other tools to increase our chances of success. Also, sometimes a repellent will work for a long time and then for some reason unknown to me, the animals I’m trying to discourage will just ignore it. Maybe they just get used to it. In any case, be prepared to change what you’re using if you find that repellent no longer works the way you need it to. Sometimes a fresh approach will do the job.
Garlic is always a good choice. In just about any form, garlic will repel all sorts of wild creatures from garden plants. Almost every creature (besides humans) dislikes the smell and taste. You should be prepared for the entire area to smell like a freshly made batch of garlic bread if you use this repellent. You can make it in any number of ways. Garlic water is simple to prepare and works very well, but it does takes an hour or so to concoct. Spreading dehydrated garlic granules on the ground around the plants you want to protect is fast and won’t make the area smell as much, but it’s more expensive.
Commercial products based on garlic oil can be sprayed on or near plants to repel wildlife. If you don’t want to have garlic flavor on your veggies and fruits, spray other plants growing in the same area instead of using garlic oil directly on food plants.
Often I am asked what might work to keep squirrels and chipmunks from digging around in the garden beds. Or I’m asked how to keep out pesky neighborhood cats intent on scratching up the soil or, even worse, using it for a litter box. My answer? Try hot chili peppers!
Capsaicin is the chemical compound in peppers (of the genus Capsicum) that makes them hot and spicy. A squirrel, chipmunk, or cat digging in soil where hot peppers have been applied will get this compound on their skin and feet. If they don’t feel it on their fur, they’ll get it on their tongue when they clean themselves. It doesn’t take long before they put two and two together and realize that at least this part of the garden is no place to mess with.
Animals dislike the burning sensation a hot pepper causes on the skin or in the nose and eyes.Humans do, too: wear gloves while handling hot peppers, and don’t rub your eyes.
I prefer to use crushed chili peppers because they’re easy to get and not very expensive. Any variety of hot chili pepper will work fine, but the hotter it is, the better and faster it will work. Choose something like crushed pequin (bird) or habanero peppers. You can find them in the grocery (ethnic or spice aisles), or you can mail-order in bulk from herb or gourmet cooking businesses. You can purchase capsicum-based garden products; some are designed for use against insects, and stronger formulations are for keeping away animals. If you use a commercial hot-pepper spray, follow the label directions for proper application. You’ll need to reapply crushed or powdered peppers if they blow away or are washed off by rain; commercial sprays will eventually wash off as well.
I sprinkle the crushed chili peppers on the ground where the critters are digging. This repellent has kept squirrels from digging good-sized holes in my planter boxes in their efforts to bury nuts for winter storage. I don’t mind them burying nuts, but sometimes they disturb fragile plants in the process. This has happened to the salad greens, and those plants had a hard time recovering.
Ground black pepper works almost as well as hot chili peppers, probably for the same reason. As the garden season progresses and the squash, pumpkins, and cucumbers are growing well, that’s about the time when squash bugs show up in large numbers. One of our remedies for potato beetles and squash bugs is to sprinkle ground black pepper around at the base of the squash and pumpkin plants. It works well on cucumbers, melons, and gourds, too. Many types of insects, as well as wild animals, don’t like being around the smell or taste of black pepper. It seems also to repel raccoons, skunks, squirrels, and rabbits. Doug, who helps us on the farm, buys giant-sized jugs of ground black pepper at the dollar store and uses it to keep squash bugs out of his vegetables.
Cinnamon and Wood Ashes
Powdered cinnamon is a great repellent for any soft-bodied insect pests that are causing trouble for fruits and vegetables. The natural oil in the cinnamon burns the body of an insect it comes in contact with, so pests just avoid it. Long ago my grandmother told me to apply a single thin line of powdered cinnamon along the baseboard and in front of the threshold to prevent sugar ants from getting in the kitchen and into my pantry goods. It works in the garden and the greenhouses, too!
Sprinkle cinnamon around lettuce plants to prevent ants from farming aphids on the leaves, or to keep them from eating strawberries. The key is to have an unbroken line of the powder surrounding the area you want to protect. If there’s a break in the line, ants will find the spot and pass through it on their merry way.
Wood ashes can be used in a similar fashion. Sprinkle them on the ground around the base of plants that are being eaten by snails and slugs. I use wood ashes around my strawberry plants when they are fruiting heavily. This remedy works well, though you need to refresh the barrier of ashes after a heavy rain. It’s best as a temporary remedy; too much wood ash can raise the soil pH enough to affect how well plants grow.
Mint (especially peppermint and spearmint) is an excellent repellent for many kinds of rodents. Mice, rats, voles, and moles have no tolerance for the smell and leave the area undisturbed. Mice and other small rodents like to eat root crops, and their digging and tunneling will damage plants. This can be a frequent problem where mulch has been left in the garden after the growing season; they find it a warm home during cold months, with a ready food supply of roots nearby. It also happens in growing structures like cold frames. If wild hunters are not keeping rodents under control, you can purchase commercial products containing dried mint or peppermint oil from garden centers and mail-order companies.
It’s important to replace mint products as soon as they begin to lose their fragrance. At that point they lose a great deal of their effectiveness. Other types of plant-based repellents that seem to keep away browsing or burrowing wildlife are products based on lemon or citronella oil, cinnamon, birch oil, balsam fir, and rosemary.
Scented Soaps and Other Fragrances
Strong-scented soap bars, tied into pieces of netting and hung in trees at nose level, will often keep bears out of fruit trees and discourage deer and elk from browsing on vegetable plants. The soap-bar tactic seems to work pretty well with raccoons, too; it has saved my sweet corn on more than one occasion. Some folks use moth balls, but because these are toxic if ingested, I don’t. My mother uses fabric-softener dryer sheets tucked in and around her vegetable garden to keep out wild critters. I’ve tied these onto our grapevines; they do seem to keep away skunks and deer, but I’ve watched the raccoons smell the dryer sheets, wiggle their noses, and proceed to eat our grapes anyway. Since most birds have no sense of smell, none of these will help keep them from foraging among fruit trees or berry bushes.
The repellents mentioned so far can be used liberally on food crops without risk, but others are not safe to eat. Make sure any repellent you employ is safe for use on food crops if you’re applying directly onto fruits, vegetables, herbs, or edible flowers. Check the label of commercial repellents. Rotten eggs and castor oil are in many products because they’re extraordinarily effective. However, if you make your own repellent from either of these, it absolutely cannot be used on any plant that will be eaten, or you run the risk of food poisoning. These products should be applied only to plants that are not grown as food, such as shrubs and ornamental flowers.
Repellents made from animal parts or excretions such as dried blood, musk oil, and animal urine keep animals away from specific parts of the garden, but they should not be applied to anything that will be eaten, and must not touch your skin. Hair or fur of predators or humans belong in this category as well. These send the message that a human or predator animal has been in the area, thus deterring plant-eating wildlife from hanging around. Sprinkle it on the ground or tuck little tufts of fur here and there under plants or around the perimeter of the food garden. Apply any repellent that contains ingredients derived from animals to the ground around the food-garden, and never to the foliage of the plants. I often apply animal-based repellents on pathways and around grape trellises to prevent animals from damaging my crops. They create an invisible boundary on the outer edges of the garden and protect fruit trees and berry bushes. As a bonus, as they break down in the soil they become a source of nutrition for plants growing in the immediate area.
A brief word about using human hair: If you’re looking to use large quantities in or around the garden, avoid hair that has been colored, permed, or treated with other synthetic chemicals. The residues from hair treatments are not always safe for people or creatures of any kind.
Repellents based on musk oil, animal urine, and animal fur create the impression that predators are nearby. Animals that might normally be hunted don’t take chances when they smell these odors. Blood and bonemeal products work by giving the illusion that an animal has died in the area, and many animals will be frightened away by the smell of death. However, wolves and coyotes, even domestic dogs, may be attracted to these types of repellents and will dig where they’ve been applied, causing much damage. You’re better off using plant-based repellents such as garlic and pepper where wild and domestic dogs are frequent visitors.
To protect my orchard trees from browsing animals once fruit begins to ripen, I spread an animal-based repellent on the ground about 2 feet out and circling the tree trunks. If a tree has low-hanging branches laden with ripe fruit, an extra temptation to animals, I put another circle of the repellent on the ground just at the outer edge of where the branches hang. This keeps deer, raccoons, elk, and even bears from finding their way into the trees or reaching up to pull off fruit. I have used these types of repellents also to keep wild squirrels and skunks from going underneath our front porch, and during rutting season to prevent deer from breaking branches and damaging tree bark.
Every day I rake or pick up any fruit that happens to fall off the trees. I dump the drops around the pear tree in the front yard, for a giveaway food station. It hardly seems fair to leave fallen fruit on the ground where animals will be attracted to it but not able to get at it because the repellent sends them away. There the fruit would just spoil and attract wasps.