Self-watering pots, also known as sub-irrigation planters, offer a consistent and efficient method for hydrating plants by reversing the traditional top-down watering approach. This system operates on the principle of capillary action, using a wicking component to draw water from a reservoir upward into the soil. The planter is divided into two sections: a water reservoir at the bottom and a growing bed for the plant above it. This keeps the root zone consistently moist but not waterlogged, mimicking how plants naturally access ground moisture. This design is beneficial for gardeners who travel or struggle to maintain a regular watering schedule, as the reservoir can sustain the plant for days or even weeks.
Essential Components and Design Choices
The construction of a DIY self-watering pot requires four primary elements to create the reservoir-and-wick system. You will need two containers: an outer, watertight vessel to serve as the reservoir, and an inner container, typically a plastic pot, to hold the soil and plant. The inner pot must be small enough to sit inside the outer one, leaving a distinct space at the bottom for water storage.
A wicking material draws water from the reservoir up into the soil. Synthetic materials like solid-braid nylon rope or acrylic yarn are effective choices because they resist rot and mildew, unlike natural fibers such as cotton. The final component is a narrow tube, such as a piece of PVC pipe, which acts as the fill port for adding water directly to the reservoir. Basic tools required for modifying the containers include a drill or a utility knife for creating necessary openings.
Step-by-Step Assembly Guide
The construction begins with preparing the inner planting container. Use a drill to create several drainage holes in the bottom of the pot, and one slightly larger hole in the center for the wicking material. Thread the chosen wicking material through the center hole, ensuring a significant portion extends into the pot to embed within the soil, while the other end hangs down several inches below the container’s base.
For the outer reservoir container, drill a hole near the rim to serve as an overflow drain. This prevents soil saturation if the reservoir is overfilled and indicates when the reservoir is full during refilling. The refill tube, often a piece of PVC pipe, should be cut so it extends from the bottom of the outer container up to just above the planned soil line.
Finally, assemble the components by placing the inner container inside the outer reservoir, ensuring the wicking material hangs down into the bottom space. Position the refill tube alongside the inner pot, resting it on the bottom of the reservoir. This configuration creates a sealed lower chamber for the water and an upper chamber for the plant, ready for the soil medium.
Planting and Ongoing Care
A successful self-watering system depends on using a well-aerated potting mix that allows for efficient water movement. Avoid heavy, dense garden soil, opting instead for a mix that includes coarse materials like perlite or coco coir to aid in wicking and prevent compaction. Place the plant into the inner container and fill the soil around it, ensuring the wicking material is fully covered and in firm contact with the medium.
After planting, the system requires an initial top-watering until water drains into the reservoir below. This thoroughly moistens the soil column and establishes the capillary connection. Subsequent watering is done by pouring water directly into the refill tube until it exits the overflow drain, confirming the reservoir is full. Periodically allow the reservoir to nearly deplete before refilling; this encourages a slight drying cycle, which helps oxygenate the roots and prevents stagnation or mineral buildup.