Repellents may be effective when deer damage is at low to moderate levels and deer have other areas in which to feed. Repellents work best when applied before feeding patterns develop and must be reapplied on a regular schedule for continued effectiveness (depending on rainfall, temperature, and growth rate of plants). Odor-based repellents often perform better than taste-based materials. Be sure to follow labeling instructions carefully and understand that repellents rarely reduce damage 100%.
Information on deer repellent effectiveness can be found at Deer.
For additional information to explain why repellents often fail, visit Why Repellents Fail
