The wick system is the simplest of all six types of hydroponic systems. That’s because traditionally it doesn’t have any moving parts and doesn’t use any pumps or electricity (some growers will still use an optional air pump in the reservoir.) Because the wick system doesn’t need electricity to work, it’s also quite useful in places where electricity isn’t available or is unreliable.
The wick system is an easy system to build when a grower is first learning about hydroponics. This hydroponic system is frequently used in classrooms to conduct experiments, both to help explain how plants grow and as a way to get students interested in hydroponics.
Items Needed to Build a Wick System
- A bucket or container for the plant
- A bucket or container for the reservoir
- A good wicking growing media like coco coir, Vermiculite, or perlite
- Some strips of material like felt or good wicking rope
A wick system operates just like it sounds; it basically just wicks up nutrient solution from the reservoir to the plants using the process of capillary action. Or in other words it sucks up water to the plants through the wick like a sponge. Good wick systems will have at least two or more good size wicks to supply enough water (nutrient solution) to the plant. The bucket/container with the plant in it normally sits right above the container used for the reservoir. That way the water doesn’t need to travel up very far to get to the growing media with plants.
The Downside of Wick Systems
The biggest downside to a hydroponic wick system is they don’t work well for larger plants that need large amounts of water. They are better suited to grow smaller non-fruiting plants, like lettuce and herbs. While the wick does suck up (wick up) moisture to the plant roots, the larger the plant is, the more water it will need. If they are fruiting plants, they will need even more water to support the growth of all the water absorbing fruit as well.
Wick systems also have the disadvantage of being less efficient at delivering nutrients. Heavier feeding plants may need nutrients faster than the wicks can supply them to the roots. Lettuce and herbs are generally light feeders, while plants like tomatoes, peppers and most fruiting plants are heavier feeders.
The plants in a wick system don’t necessarily absorb nutrients and water evenly and the wick can’t tell what nutrients the plant needs. The plants take the nutrients and water they need and leave the rest of the nutrients in the growing medium which can eventually cause a toxic buildup of mineral salts in the growing media. As a result, flushing the excess nutrients from the root zone (growing media) with plain fresh water should be done regularly, like once a week or so.
The wick itself is probably the most important part of the wick system. Without a good absorbent wick the plants will not get the moisture and nutrients they need so it’s a good idea to test different materials to see what works best for you. When looking for a good wicking material, you’ll want to use something that’s absorbent, but is still resistant to rotting. Make sure to wash the wick thoroughly before using it which can significantly improve the wicking ability of most materials.
Some common materials used for wick systems include fibrous rope, propylene felt strips, tiki torch wicks, rayon rope or mop head strands, braided polyurethane yarn, wool felt, wool rope or strips, nylon rope, cotton rope and strips of fabric from old clothing or blankets.
Make sure to use enough wicks to support the plants water usage. The number needed will depend on how the wick system is built, the type of plant being grown, and growing medium being used. Most systems require at least 2-4 wicks unless they are very small. Also the shorter the distance up the wick the water has to travel from the reservoir to the growing media and roots, the more water it can transport to the growing media.
It is best to use a very absorbent growing media to aid the wicking up process and hold moisture. Some of the most commonly used growing media for wick systems are coco coir, vermiculite or perlite. And in some cases, even water absorbing polymer crystals can be used.
The wick system reservoir can be large or small as long as it never runs dry. The water level should remain high enough, so the water (nutrient solution) doesn’t need to travel up the wick very far to get to the growing media and root zone. It is best to consistently top off the reservoir with fresh nutrient solution as needed. Algae and microorganisms can begin growing in food rich water, especially if it isn’t in a light proof area, so make sure you occasionally clean the system and change the nutrient solution.
Because the wick sucks up water and nutrients evenly, and the plants don’t use or absorb them evenly, a buildup of excess nutrient salts can accumulate in the growing media over time. As a result, it should be flushed with plain fresh water every two weeks. This reduces the likelihood of the nutrient salts building up and reaching toxic levels for the plants.
Optional Air Pump
Using an air pump and air stone to aerate the water in a wick system isn’t necessary, but it can be beneficial. While the roots should be able to get oxygen from the small air pockets in the growing medium, they also absorb dissolved oxygen directly from the water itself as well. Along with helping to aerate the water, the moving, and rising bubbles keep the water circulating. Keeping the nutrient solution water moving around keeps the nutrients in it evenly mixed. If the water is still, the nutrients can settle toward the bottom over time.
Jeff Sanders owns HomeHydroSystems.com a hydroponic website designed to help hydroponics enthusiasts learn how to build their own hydroponic systems, as well as learn about many topics related to hydroponics.