A watering bell is a specialized device designed to provide controlled, gentle hydration to plants. Often crafted from porous materials like terracotta or non-porous ceramic, it acts as a reservoir that regulates water delivery to the soil. This simple tool helps gardeners manage the moisture needs of their plants efficiently, preventing the stress that comes from inconsistent watering. Its primary function is to offer a more measured and sustained approach to plant hydration than a traditional watering can.
What Watering Bells Are and What They Look Like
Watering bells, sometimes called thumb pots or aqua globes, come in two main types. The traditional design is a stoneware or ceramic vessel shaped like a bell or pear, featuring small holes at the base and a single opening at the top. This type, often made from glazed ceramic, is used like a delicate watering can: it is submerged to fill with water, and the top hole is covered by a thumb to control the flow of a gentle “rain” from the base holes.
The second, more modern variation is the self-watering bell, frequently made from porous, unglazed terracotta or a glass bulb with a long, narrow neck. Terracotta bells are typically cone-shaped spikes that are inserted directly into the soil, while the glass versions feature a decorative bulb reservoir that sits above ground. These self-watering designs function differently from the thumb-controlled versions by acting as a passive water reservoir that maintains contact with the soil.
The Mechanism of Slow, Deep Watering
The mechanism of water delivery differs significantly between the two types of watering bells. The glazed ceramic thumb pot relies on basic physics and air pressure for its gentle “rainfall” effect. When the top hole is covered, the resulting vacuum prevents air from entering the vessel, which stops the water from flowing out of the small holes in the base. Removing the thumb allows air to enter, and gravity releases the water in a controlled, low-pressure stream that does not disturb delicate seedlings or soil.
The unglazed terracotta spike or porous ceramic bell operates on the principle of capillary action and soil moisture tension, similar to ancient olla irrigation systems. The porous clay material has microscopic pores that hold water and only release it when the surrounding soil begins to dry out. As the soil moisture decreases, the negative pressure, or tension, in the soil increases, which effectively draws water out of the porous clay material and directly into the root zone. This creates an on-demand watering system where the plant and soil dictate the rate of water release, ensuring precise hydration.
When to Use a Watering Bell
Watering bells are particularly advantageous where consistent moisture and gentle application are beneficial to plant health. The thumb-controlled ceramic bell is a useful tool for watering young seedlings and tender plants that can be damaged by a heavy flow of water. It replicates a soft rain, which prevents the compaction of soil and the exposure of roots that can occur with high-pressure watering.
The self-watering, porous bells are ideal for maintaining a uniform moisture level in potted plants, preventing the stress associated with cycles of over-drying and over-watering. This consistent delivery encourages deeper, healthier root growth. The reservoir capacity of these bells makes them a popular solution for providing hydration when the gardener is absent, such as during a vacation. Using these devices ensures that water is conserved because it is delivered below the soil surface, minimizing loss to evaporation.
Practical Setup and Care
A porous watering bell should be fully saturated before use to prevent it from drawing moisture from the soil. Soaking the terracotta spike in water for a few minutes ensures it is ready to begin releasing water immediately. When placing the bell, insert it into the soil away from the main stem, near the active root zone.
The reservoir is then filled through the exposed opening, which should be covered to minimize evaporation and prevent debris or pests from entering. Over time, mineral salts from tap water can build up on the porous material, impeding the flow of water and requiring periodic cleaning. Soaking the bell in a diluted vinegar or mild soap solution and gently scrubbing the surface maintains its functionality.