Wick Systems are the most basic form of hydroponics and are incredibly easy to set up. They are a great introduction for beginners or students looking to learn the basic principles of hydroponics without having to deal with the complex mechanisms of other systems.
Wick Systems are passive, meaning they have no moving parts. This makes them easier and cheaper to maintain than active systems such as Ebb and Flow, but they also have the drawback of being less efficient and not well equipped for high-maintenance plants, or large plants that consume a lot of water. The best plants to use in this system are fast growing lettuces or herbs. Herbs such as rosemary that doesn’t require a lot of water are the best choices, while thirsty plants such as tomatoes would not do well.
The way a Wick System works is similar to the Lettuce Raft Method because the roots are always in contact with water. The difference is that a Wick System uses two or more wicks to deliver water from the reservoir to the roots via capillary action; while in a lettuce raft the roots are submerged in the reservoir itself.
One of the biggest drawbacks of Wick Systems is that they cannot handle very thirsty plants such as tomatoes. The best plants to use in Wick Systems are fast growing lettuces as well as herbs. Herbs such as rosemary that do not require very much water are the very best choices.
There are four main components in a Wick System—the grow tray, reservoir, wick, and aeration system.
The Grow Tray
The grow tray in a Wick System differs from other hydro setups in that it does not use net pots to hold the growing medium. The growing medium fills up the entire tray, with seedlings transplanted directly into it. The best kind of growing medium to use in this system is one that will not drain too fast and will utilize the capillary action of the wick most effectively. Vermiculite, perlite, and soilless mixes are all good choices—they have good wicking abilities but will not become soggy like traditional soil.
The reservoir is much the same as in any other system. It is a large container of fertilized water that sits below the grow tray and supplies water and nutrients to the plants. The water in the reservoir must be refreshed every week or so because the strength of the nutrients diminishes as the plants absorb them.
The Aeration System
The most common aeration system is an air stone and pump. The air stone, much like those found in home aquariums, is placed in the water and connected to an air pump outside the reservoir. The pump pushes air through the stone, which blows out tiny bubbles to distribute oxygen through the water.
It is essential to the health of the plants that their roots are oxygenated. In traditional gardening and active hydro systems, this is accomplished partially by letting the roots dry out in between watering. Active systems also use air stones to oxygenate the water, but in a Wick set-up, the aeration system is especially important because the roots never have a chance to dry out completely.
The reservoir is connected to the grow tray by two or more wicks. The wicks utilize capillary action to transport nutrient solution into the growing medium and to the roots of the plants. The easiest wick to use is a cotton rope, but after a while, it can be susceptible to mold or rot. If you plan on using the system for extended periods of time, make sure to check the rope periodically. Alternatively, nylon rope is very effective and does not mold or rot.
The wicks are inserted into the grow tray through small holes. You may want to add either a rubber connector or make sure the holes are slightly smaller than the wicks to prevent any growing media from falling through the holes.
The number of wicks used depends on a number of factors—the total system size, plants used, growing medium, and wick material will all have an effect. A good rule of thumb is to use one wick per plant and make sure the tip of the wicks is placed near the roots. For water-hungry plants and large systems, two wicks per plant may be necessary.
If you were setting up a Wick System in the classroom, a fun experiment would be to test different types of rope to see which has the best wicking ability. Just stick the ends into a cup or bowl of colored liquid and measure how fast and how much liquid each sucks up. Washing the rope can have a significant impact on its wicking ability, so make sure to test all of your wicks both washed and unwashed and compare the difference. Depending on your results, you can decide how many and which type of wick your system will need to be effective.