Ask a Master Gardener: Deer eat 'deer-proof' plants
Extension recommends spraying with a repellent that contains egg putrescence.
Q: Yesterday I had a pretty pot full of geraniums and coleus. Today I have a pot of stems. What can have eaten them? I thought deer did not eat geraniums.
A: Many sources say geraniums are not favored by deer. But deer don’t read the flower books, and they will eat just about anything if they’re hungry enough. Something ate the basil I planted this year, and I suspect it was deer, who have always left it alone in years past. A neighbor says they ate her cosmos, which they’ve never touched before. Another neighbor says they ate her lilacs, which are on everyone’s list of plants deer don’t eat.
Extension recommends spraying with a repellent that contains egg putrescence, and I’ve had good luck protecting deer favorites such as hosta with that.
The repellent spray is only meant for ornamental plants, though, not edibles. Apparently I will have to grow basil behind a fence, since I want to eat it and the deer in my neighborhood have discovered a taste for it.
Many of the other folk methods for deterring deer are not supported by scientific research. Sprinkling human hair or hanging bars of soap is unlikely to be effective.
If you want to make your own repellent, Extension recommends this recipe. You can find other recipes online, but they often call for adding ingredients, such as garlic or peppermint, that make the spray less effective than one made with just eggs and water:
1. Use a blender to blend three whole eggs thoroughly in water.
2. Pour the mixture into a container and add water to reach 1 gallon.
3. Strain this mixture. If you don’t, it’ll clog your sprayer. It may clog the sprayer anyway.
4. Put the mixture into a spray bottle and thoroughly spray the leaves, buds and flowers of the plants you’re trying to protect.
It will smell bad when you first apply it, especially if it’s been sitting for a while, so don’t do this right before a garden party. By the next day, the smell will die down to your nose but will still be noticeable to deer. Be sure to spray new growth, and spray again after rain.
There’s more information about deterring deer at extension.umn.edu/central/protecting-plants-deer#considerations-1556112.
Written by U of M Extension Master Gardeners in St. Louis County. Send questions to firstname.lastname@example.org .