Self-watering planter

A self-watering planter has two parts, a normal potting mix chamber on top and a sealed reservoir underneath, connected by a wick or capillary column that draws water upward as the soil dries. Instead of watering the surface every day, the gardener fills the reservoir every few days to a week or two, and the plant pulls up only as much moisture as it needs, which helps prevent both drought stress and overwatering.

This style suits balconies especially well because sun and wind dry small containers out quickly, and many balcony gardeners are away from home during the day or on trips. A fill tube or window usually shows the water level, so there is no guessing about when to refill. Most models still need a normal drainage overflow so a heavy rain does not flood the reservoir past its capacity.

When buying one, check the reservoir size relative to the plant, a small reservoir under a large tomato plant in summer heat can still run dry within a day or two. A common mistake is packing mix too tightly around the wick, which blocks water movement, or forgetting to flush the reservoir occasionally to prevent salt and fertilizer buildup at the base of the soil column.