If you still have some worms in your bin, you may be able to increase the population by carefully tending your pile. FYI, worm bins slow down in cool weather. In winter, it may be good to add browns—such as shredded newspaper or cardboard—to prevent the worm bin from getting too soggy. The lower population of worms require less food. As the weather warms in April and May, the worm population picks up and worm activity increases.