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Gardening: South Spokane resident sings praises of Milorganite for repelling deer

Arlene Johnson spreads Milorganite granules in her South Hill garden to ward off hungry deer. (Pat Munts / The Spokesman-Review)
Arlene Johnson spreads Milorganite granules in her South Hill garden to ward off hungry deer. (Pat Munts / The Spokesman-Review)

In polite company, deer are often referred to as marauding hooved garden thieves or garden buggers. Arlene Johnson has an entirely different vocabulary of words she uses to describe them in the privacy of her two-acre property just across from Lincoln Park on Spokane’s South Hill.

In the fifty years she has lived on her wooded land she has used every commercial and home brew spray deterrent she could find. She doesn’t like fencing off all her plants. “Fences look terrible and I hate to make my garden into a fortress,” she said as we walked around the garden.

Unexpectedly, Johnson recently stumbled onto a fertilizer that also seems to repel the deer from her garden. Milorganite is a granular lawn and shrub fertilizer created nearly 100 years ago by the Milwaukee Metropolitan Sewerage District. It processes wastewater from the Milwaukee area using natural microbial processes. The cleaned waste water is returned to Lake Michigan and the microbes are dried and made into fertilizer. While not originally packaged as deer repellent, empirical and research evidence points to it being a moderately effective repellent.

Deer are by nature browsers. They use their senses of smell and taste to identify edible plants. During the summer, they eat the tender green leaves of a wide variety of domestic and wild plants. During the winter, their stomach chemistry changes, and they forage on twiggy brush and conifers. While the wild areas are still green and lush, they prefer to stay in the safety of the woods. However, once the wild areas dry out in mid-July, our gardens look really tasty and they move in. Johnson is waiting until then to fully confirm that her spring observations hold through this period.

Most common commercial and homemade repellents repel deer by making the plant either taste or smell unappetizing. Rotten eggs, garlic, coyote urine, dried blood, bittering agents and hot pepper are common ingredients in sprays. Coyote urine and blood meal are thought to repel because they smell like predators the deer naturally avoid. The strong scent of garlic and the hydrogen sulfide in rotten eggs deter by scent. Bittering agents and hot pepper make the plants taste bad. Research didn’t say what the deer repelling component of Milorganite is.

One of the major advantage of commercially prepared repellents, including Milorganite, is that they can withstand repeated rain or sprinkler spray for several weeks. Most homemade repellents must be reapplied after every rain which can be difficult to keep up at times with our busy schedules.

Still, one of the best deterrents is a good 7-foot tall fence. But as Johnson said they can be ugly and make the garden look like a fortress. One solution is to design a good-looking fence that blends into the character of your landscape and then put the plants they really like and you really want to keep inside it.

Milorganite is available at garden centers including Northwest Seed and Pet. Experiment with it on a few plants before you bet the garden.

Pat Munts has gardened in the Spokane Valley for over 35 years. She is co-author of “Northwest Gardener’s Handbook” with Susan Mulvihill. She can be reached at pat@inlandnwgardening.com.