Deer Ban is effective for up to 90 days. As stated earlier, extreme dryness can affect the efficacy and extremely heavy rain could wash the product away. Compared to other repellent products on the market, however, Deer Ban should provide a much longer period of control. Deer Ban targets the deer survival instinct, and once a deer determines that there is a predator in an area it will leave the area and typically not return. Continued success though, is always accomplished by regular re-application to prevent other deer from moving into the area.