The wick system is possibly the simplest hydroponic method, is very water efficient and does not utilize any moving parts in its operation. Its major advantage is the low level of maintenance involved. A versatile system, it can be adapted to many garden types, from a SOG closet setup, to guerilla growing in the bush. It can also be adapted for organic propagation techniques.
In its simplest form, the wick system is comprised of two containers, one on top of the other. The upper container holds the soil or growing medium, while the lower container holds the water or nutrient solution. One or more wicks pass from the upper container into the lower one where they are suspended in solution. The solution is transmitted into the growing medium by capillary action.
Various types of growing media may be used successfully in this system, however care should be taken to choose media which are conducive to capillary action. Hydroton expanded clay balls are a good choice for the hydroponic version of this system. Good quality potting soil mixed with rich compost and/or worm castings and 30% perlite would be a nice mix for an organic system.
The wicks should be made from either strips of capillary matting, felt, or from nylon rope. It is advisable to choose uncoloured materials for the wick, as the colours could be toxic to the plants.
The reservoir can just be topped up manually when it runs low, or could be connected to an additional reservoir. A ball float can be used, or as shown in the attached diagram, the reservoir can be run on a vacuum system. I was shown this method by a local grower from Adelaide.
VACUUM REGULATED RESERVOIR:
A generic 20ltr water container can be used from which 2 lines run into the main reservoir, one from the top and one from the bottom of the container. This reservoir must be completely sealed (i.e. totally free of air leaks). The 20mm lines are sealed with rubber grommets, and the lid has a rubber seal also. Negative pressure inside the container stops it from flooding the reservoir. Once the water level drops below the level of the upper line, air is sucked into the container. This causes solution to flow into the reservoir until the water lever blocks more air from being sucked up. This action maintains the main reservoir topped up as long as the second container is full. Various configurations can be used depending on the garden's needs. The additional reservoir can be used to run several pots, or several reservoirs may be ganged on a single pot.
The wick system, especially when connected to an additional reservoir as mentioned above has huge benefits in guerilla growing where regular watering and maintenance is not possible. Such a system may be left unattended for weeks or months at a time. To prevent the roots from becoming waterlogged in case of heavy rain, one or more drainage ports could be installed as shown in the diagram when using the system outdoors. Alternatively, the run off could be collected in a reservoir.
The wick system does not produce growth rates comparable to other hydroponic systems such as DWC, but it is a very versatile and very simple method with its own advantages.