In a well-ventilated area or a protected area outside (such as in a garage or a shed). Make sure that the temperature in the area you choose is above freezing (0°C or 32°F.) Check the container at the end of one week, and record any changes in the water level and the appearance of the leaves and twigs. Add another two-inch layer of wet sand on top of the leaves and twigs, and let it sit to dry for two weeks.