Yes, you can whip up your own foul smelling spray to deter deer from eating your plants. The popular rotten egg and garlic blend is the base of just about every homemade deer repellent recipe out there. Some people add hot sauce or cayenne pepper too. This may be overkill. There are commercial deer repellents that are very effective that contain no capsaicin at all.
Why do you suppose it’s in some and not others? It very well could be that the preparation was marketed as deer and rabbit repellent, or the miracle product that repels every garden varmint known to man. Look at the actual name of the product on the label. Chances are, if it is only targeting deer – it contains no hot pepper at all. Instead the active ingredients from natural sources are garlic and/or putrescent eggs. Because capsaicin has proven less effective at repelling deer.
Whether the product is supposed to protect your garden from deer and rabbits, or deer alone, better quality sprays are rain-resistant. Achieving this requires adding a surfactant, sometimes called spreader/sticker. This helps the repellent spread over the surface of the leaf, and hold up better under moisture from sprinklers and rain. If there’s no sticker – your repellent melts away readily anytime water hits the leaves. Even heavy dew and fog can cause it to dilute and slide off.
There are basically 2 kinds of stickers that manufacturers use for deer repellents:
1) Resin or latex as is found in antidessicants, such as Wilt-Pruf. These aren’t organic or natural, and aren’t the greatest thing to coat a plant’s leaves with. It plugs the pores of the leaf surface, and is designed to stop winter burn or slow down moisture loss in conditions that cause plant stress.
2) Natural oils are what non-chemical and organic deer repellents contain to help them stick to leaf surfaces even in the presence of rainfall. But they can also be both a surfactant and an active ingredient.
And in homemade deer repellent recipes, people suggest you add milk, dish soap, or vegetable oil. Dish soap will help the droplets from your sprayer spread across leaf surfaces better. It’s also great added to weed killer spray tanks for the same reason. However – just like what happens in the kitchen sink – dried dish soap instantly melts when you add water. So, it’s never going to help make your deer spray resist rain or irrigation. And milk will leave a white film on your foliage.
Vegetable oil is very heavy, kind of like motor oil, when what we need is more like a lighter spray lubricant. It will be very difficult to keep it mixed well in your spray tank. Consider how hard it is to keep vinegar and oil dressing from separating just trying to add it to your salad.
Just putting it in the mixture isn’t helping anything. It needs to stay in-solution for a DIY deer spray that actually protects your plants. If it separates during application, your active ingredients will be in some spots and the sticker in others. And vegetable oil won’t dry fast, which you need the oil in your mix to do.
You’d be a lot better off trying lighter weight plant extraction oils. Like those from the very plants that deer rarely eat. They don’t like mint or rosemary, and while cinnamon and clove aren’t plants we grow in many climates, they should have a similar effect. All are pungent plants that work to disguise the protected plant’s natural smell, and taste bad to deer, in addition to making the diluted egg stick better. Not that dried-on egg is easily gotten rid of – as anyone who does dishes already knows. Dried on garlic juice or hot sauce? Removing that by soaking is a piece of cake.
Finally, there’s the garlic that is part of the active ingredients in many commercial deer repellents. But you really don’t need it – unless you enjoy the stench of it mixed with rotten eggs. Studies show the most effective deer repellent without resorting to toxic chemicals is actually rotten eggs. And if mixed with pleasant smelling stuff and diluted, it won’t repel you too.
Makes 7 pints of spray. Need more than a gallon per application? Double or triple the batch, IF you’ve got a container that will hold several gallons. If all you have is 1-gallon jugs – mix a separate bowl of active ingredients for each one.
- In a small to medium sized mixing bowl add: 1 large egg, 1.5 cups of water, 1.5 teaspoons rosemary oil, and 1 teaspoon of peppermint oil.
- Whisk it by hand or with your electric mixer until thoroughly blended.
- Slowly pour the mixture in the bowl through a sieve into another bowl or large measuring cup. You want to make sure that no membrane strings remain. They will clog up your sprayer.
- Pour the strained mixture into a gallon milk jug. (Wash it out first. Cottage cheese clogs spray nozzles too.) Put the cap on, and place the jug in the sun to brew for 3-4 days.
- Once your sun-brewed putrescent eggs are ready, you can dilute to spray. It might be a bit smelly when the cap comes off, but not for long. Add 6 pints of water. Cap it again, and shake to blend. Put it in your sprayer and apply to plants.
Mist-spray all levels to thoroughly wet the surface. Be sure that it will have 2-3 hours to thoroughly dry before rainfall, sprinklers activating, or dew-fall. It should last at least 2 weeks, perhaps more. However, during spring and early summer, new growth is coming on quickly and needs further protection. So, just plan on having to respray every 10 days or so – just like you should with any deer repellent. Do not apply to fruits and vegetables.
If you must have capsaicin to rest easy, by all means, toss in a couple tablespoons of Tabasco sauce or one tablespoon of red habenero hot sauce. I don’t think it will be necessary. And to keep the element of surprise, vary the lesser amount of essential oil in each batch. Start out with the mint, but switch that 1 teaspoon in the next batch to clove oil or cinnamon oil. Then go back to the peppermint oil on the next go round. But don’t swap out the rosemary oil.
The recipe is based on what I’ve learned from university studies, other homemade deer repellent recipes that supposedly work, and the best commercial deer spray I’ve used. Note that I haven’t tried this yet, though I am contemplating doing so this summer. The problem is that not only will this take pre-planning, it will cost more to make than simply buying an effective manufacturer’s repellent. The cost per batch does go down if you buy essential oil extracts in bulk. But with my ridiculous schedule, being able to just grab the concentrate and mix up a sprayer full on demand will probably win out! Still, I’m curious to see if this works as well as my go-to deer repellent product 😉
Image courtesy of Piasoft (CC by 3.0).