Bottom watering is a practice where the plant is set in and absorbs water from a container filled with water. Plants regularly watered from the bottom should occasionally be watered from the top to get rid of excess salts in the soil. The bottom layer of soil becomes saturated when a plant continuously sits in water. Any roots growing in this saturated layer will die. The soil available for plant growth is thus reduced.
Some plants enter rest periods at some time of the year.
Resting plants may use less water so are more likely to be overwatered. If a plant slows or stops growing in late fall or early winter, it may be entering a rest period. At the same time the furnace may start running and dry the air out, causing the soil to dry out more quickly. Concern about overwatering resting plants in winter must be tempered by consideration of the effect of lower house humidity.