Keeping kefir grains in the fridge or a cold place makes them stop multiplying. Leaving your grains at room temperature for a length of time, and adding only room temperature milk, may help them become more active. Also, don’t squeeze or wash your grains, which traumatizes them. Avoid using too many grains in too-small an amount of milk. Two tablespoons of grains in 2-3 cups of milk each 1-2 days is a good average amount. Also, use raw, whole milk.