A water bulb, also known as a watering globe or spike, is a self-watering device designed to deliver a steady supply of moisture to potted plants. These tools feature a glass or plastic bulb attached to a long stem inserted directly into the soil. Their primary function is to maintain consistent soil moisture, which is helpful for plants preferring damp conditions or when homeowners are away for a short time. The system works based on a weak vacuum created inside the globe. As the surrounding soil dries, air enters the stem, breaking the vacuum and allowing water to trickle out until the soil is sufficiently moist.
Preparing and Filling the Water Bulb
Before using the globe, thoroughly water the plant until the soil is fully saturated. Inserting the stem into very dry soil causes the water to drain out rapidly, emptying the bulb quickly because the soil absorbs moisture too fast. Moist soil acts as a partial seal, slowing the initial release of water and ensuring the longest duration of use.
When filling the bulb, dip it into a container of water or hold it under a gentle stream of tap water. Submerging the globe allows air to bubble out as the reservoir fills. Fill the globe approximately three-quarters full to prevent spilling when inverting it for insertion. Using filtered or distilled water helps reduce the buildup of mineral deposits inside the globe over time.
Proper Insertion and Positioning
Avoid forcing the stem directly into the soil, which can compact the medium or risk breaking the glass. Instead, use a pencil, chopstick, or dowel to create a pilot hole deep enough to accommodate the full length of the stem. This prevents the stem opening from becoming clogged with soil particles, ensuring a smoother flow of water.
Insert the stem gently into the pre-made hole near the plant’s root zone, ensuring it does not press against any major roots. Positioning the globe at a slight angle promotes a smoother and more consistent water release. Lightly firm the soil around the stem to secure the globe in place. If a rapid rush of bubbles occurs, the water is draining too fast; push the stem deeper or adjust the angle to increase soil contact.
Ongoing Care and Troubleshooting
A water bulb typically lasts one to two weeks, depending on its size, the plant’s water consumption, temperature, and soil type. Check the water level regularly, removing, refilling, and replacing the globe when it is nearly empty. Testing the duration before travel helps establish an accurate refilling schedule for your specific environment.
A common issue is the clogging of the narrow stem, usually caused by soil, algae, or mineral deposits. If the water stops flowing, the stem can be cleared using a narrow tool like a pipe cleaner or cotton bud. For stubborn buildup, soak the globe in a solution of water and vinegar to dissolve mineral deposits. Regularly cleaning the bulb, generally once a month, ensures the device functions properly and prevents the buildup of organic matter.