The term “passive” means that the system is not equipped with a pump, but rather operates by the capillary forces of the wick, which lifts the nutrient solution from the tank into the root zone. With potted soil, these methods have been used for many years in nurseries or flower shops. Houseplants are often cultivated on them, mainly because these systems can for a time support the life of deciduous green ornamental plants that grow very slowly, if ever.
Design
Here’s how this system works in hydroponics: The plant is placed in a pot with an inert substrate. Below the pot is a supply of nutrient solution. A wick, made of cotton or synthetic fabric, hangs from a hole in the bottom of the pot. Due to capillary forces, the wick supplies the roots with a nutrient solution. In a more efficient version, a slot is made along the entire pot. A capillary mat hangs from the slot into the lower nutrient solution reservoir.
Substrate
When these systems are used with potting soil, a wick or capillary mat maintains the moisture in the potting soil. In this case, they are great systems, because they provide efficient automatic irrigation with a large enough supply of water, which will last for two to three weeks. It is quite another matter when the wick is used with an inert substrate: capillary forces are not enough to adequately moisten the entire root felt. In addition, mineral salts have to be added to the water to feed the plants. These salts quickly settle on the wick or mat and dry out, blocking the capillary effect. The already weak water circulation practically stops.
Vermiculite, peat moss and coconut coir are used as substrates in passive systems.
Conclusion
Don’t try to use such a system to grow voracious, fast-growing plants! This system is more of a gimmick than a cultivation method. If you want to enjoy all the benefits of hydroponics, you need a pumped nutrient solution that dynamically and continuously maintains the oxygen level in the water.
Literature
- William Texier. Hydroponics for everyone. All about home gardening. – M .: HydroScope, 2013 .– 296 p. – ISBN 978-2-84594-089-5.
