For many years, reports from the gardening underground have filtered up that deer can't abide the smell of Milorganite, that very old and pungent line of, shall we say, granular fertilizer. I tried it in a large and unfenced vegetable patch last year and had excellent results.
Les Hulcoop, a Cornell Extension agent in Dutchess County, New York, has tested it on some ornamentals known to be deer candy. He says it worked remarkably well in his plots of mixed yew shrubs, tulips, and hostas. The deer completely avoided patches with Milorganite sprinkled around the plants and ruined the plots that had none. Hulcoop reports that Milorganite works best early in the season and in summer, a time when tender new garden plants are at risk. In winter, when the deer have less choice of food, Hulcoop surmises the Milorganite probably wouldn't perform as well.
The recommended rate of application is about 5 pounds per 100 square feet. Reapply it every two to four weeks. One of the best things about this kind of deer repellent is that it is a bonus for the plants. Milorganite is a high-quality, slow-release fertilizer. It has the highest EPA safety rating, even on vegetables. Milorganite is made from partially composted sewage from the city of Milwaukee that has been dried at intense heat. It may yet become known as the brew that made Milwaukee even more famous.