The Bonsai humidity tray is sometimes referred to as “drip” trays, for obvious reasons. Most bonsai tree containers have holes in the bottom to allow excess water to drain. Typically, a bonsai tree is watered thoroughly in a sink or bathtub, and then allowed to drain before being placed back on display. Often, water seepage still occurs, and can damage the surface of the display area. The watermarks created by this can ruin the finish of hard surfaces, especially wood. The humidity contained in the soil by these drainage holes can also cause varnished surfaces to bubble and crack. A humidity tray creates a barrier between the container and the display surface which serves a dual purpose. It not only protects the surface of the display area, it creates much needed humidity for the growing bonsai tree.
Plants lose water through their leaves in a process called transpiration. A very dry climate increases the rate of transpiration, and can ultimately lead to the bonsai tree being under watered. Homes with central heat or air, trees sitting close to ventilation ducts, or trees exposed to sunlight can dry out very fast. Using a Bonsai tray under the container alleviates this problem. By allowing the freshly watered tree to drain out into the humidity tray, the collected water raises the humidity level around the tree and slows transpiration. As the soil in the container dries out, the roots will pull water back up from the humidity tray. This process allows the tree to receive just the right amount of water and increases the amount of time between full saturation watering.
The humidity tray should not be used as the sole method of watering the tree. It will not replace deep saturation watering in a sink or bathtub. Plants need to be watered from the top on a regular schedule even when using a humidity tray. The roots can pull water up through the soil, but this isn’t sufficient for long term care. The soil inside the container needs to be monitored and kept at adequate saturation levels at all times. The use of a humidity tray simply aids in maintaining the humidity level around the plant and allows the roots to draw extra moisture as needed. A good rule of thumb is to deeply saturate your bonsai tree, allow the excess to drain into the humidity tray, and then watch the water level in the tray. When the tray dries out, it’s generally a good indication that the tree needs watering again.
Some containers come with a built in humidity tray, but some are more decorative than functional. If you choose a built in Bonsai drip tray, make sure that the tray is of adequate size to hold the drainage from a standard deep saturation watering. After you remove the container from the sink or bathtub, watch the tray as it fills, and make sure it doesn’t overflow. If it does, you should consider a larger model. Containers without humidity trays attached allow for experimentation. Perhaps your home is very dry and you notice the water in the humidity tray evaporates very quickly. You would want to consider getting a larger tray. On the other hand, if the water in the tray seems to take an extremely long time to evaporate, perhaps a smaller tray is in order.
By having the Bonsai container and Bonsai tray separate, you can easily change the look of the bonsai tree when using it as a focal point. If the container is a neutral colour you could add a humidity tray in practically any colour or theme. This alleviates the need to re-pot the tree simply because it doesn’t match the surrounding décor Available display space can also effect the size of the tray. You might want to consider a large tray when using the tree as a focal point on a table, and a smaller one when displaying the tree on a windowsill or shelf. Large trays allow room for decorative humidity stones, while small ones save on space.
Even the most avid household plant enthusiast can forget to water the plants, or need to be gone for a few days. By using a humidity tray and monitoring the amount of water it contains, you can increase the time between saturation watering without fear of damaging the bonsai tree. For large trees, or heavy containers, you can water them in place when using a humidity tray. Simply pour the water slowly into the top of the container until the drainage begins to fill the humidity tray. This is especially beneficial when the tree is being used as part of a large display and moving it for watering would leave a void in the focal point. A well managed and maintained bonsai tree can give a lifetime of beauty to the caregiver. By choosing the proper Bonsai tray, you can assure the tree is receiving adequate water and humidity, and easily change the appearance of the tree to match any décor.