How to Build a Hydroponic Wick System

The wick system is a very simple passive hydroponic system. There are no moving parts which makes it low maintenance as well as cost effective. The liquid nutrient bearing solution is drawn into the growing medium to be accessible to the plants root systems via an absorbent sponge like wick.

An efficient wick system generally has several good size wicks in order to supply adequate nutrient bearing water solution to the plant. The container holding the plants sits directly above the reservoir container leaving minimal distance for water to travel between both points. The wick will carry the water to the lowest level of the grow medium, from there it migrates up via capillary action.

Although this system is low maintenance so far as moving parts, pumps, circulators and so forth is concerned, it is not without some drawbacks.

Limitations and Drawback to the Wick System in Hydroponics

Large systems bearing multiple plants, or even large plants with single wicks use larger amounts of water and at times use it up faster than the wicks are able to replenish it.

Being unable to keep up the pace so far as water delivery creates a two fold issue. The first naturally being water, but keeping in mind that the water in hydroponics also carries essential plant nutrients, wicking falls short is this realm as well.

Wicking can not always keep up with the plants nutrient requirements, particularly on plants that are heavy feeders. Not only does this system not keep pace with the plants requirements so far as water and nutrients it also does not distribute the aforementioned at a uniform rate.

The plants will absorb what they need, when they can get it, but at times leave behind excess nutrients in the grow media which causes a salt buildup which under some conditions can become toxic. Regular flushing is needed.

Small plants that are not fruit bearing fare best using a wick system. Leafy vegetables such as lettuce, mint and assorted herbs. Fruit bearing plants even small berries will need larger amounts of water to facilitate their growth especially during the fruiting stage. The wick can generally not keep pace

Elements of a Wicking System

Diagram Passive Hydroponic Wick System

The Wick

The wick needs to be a highly absorbent material that is resistant to rot.

Materials that have been successfully used for wick systems include, felt strips, tiki torch wicks, mop head strands, wool rope or strips, cotton rope. Wash the wick thoroughly before using it, not only to remove any potentially harmful resides but to enhance its wicking capacity. Don’t try and get by with minimal wicks, the more the merrier. You also want to minimize the distance the water travels from the reservoir to the growing media. 

The Reservoir

The reservoir should be large enough and the water level maintained at sufficient levels to allow the shortest feasible distance between the reservoir and media – root zone. A light proof reservoir is best to avoid algae buildup.

Growing Media

As stated earlier in this article the biggest drawback to a wicking system is its inability to always keep pace with the water and nutrient demands of the plant[s] for this reason you’ll want to use a grow media that will help the wicking process, one that is absorbent and will retain water, not one which water will simply run off of. Avoid clay balls [LECA] they are not very water retentive. A vermiculite / Perlite blend, sphagnum moss and coco coir are suitable. Perlite has a neutral pH and will not affect the alkalinity or acidity of your solution. It is inexpensive and reusable.

It is also very porous and has excellent wicking action, meaning that it will absorb and draw up liquids via capillary action. It draws up nutrient solution and water from the reservoir at a steady rate.

Used solo perlite has some drawbacks. It is buoyant and will float which can be an issue. It produces a dust that is unhealthy for humans, and is also a nuisance in the solution as it contributes to sludge and clogging. It must be thoroughly washed before using. Using a Perlite / Vermiculite blend eliminates / minimizes most of the aforementioned issues.

The Grow Bed

The grow bed or tray in a Wick System differs a tad from other hydroponic systems in that it does not use net pots r similar contraptions to hold the growing media or plants in place . The growing medium should fill up the bed and seedlings are transplanted directly to the media. Drainage is necessary but a slow draining tray / bed is best to facilitate capillary action.