Wick System Hydroponics

Wick systems are the simplest of all types of hydroponics as there is no need for any moving parts (such as a water pump) or electricity in the basic form. Wicks deliver water and thus nutrients to the roots using the capillary effect.

ProsCons
Simple, no moving parts in its basic form; though an aerator improves yieldsSlow in moving water
Good for smaller plants not bearing fruitsNot good for fruit-bearing plants
Little to No experience requiredMay build up nutrient crystals in the growing medium leading to toxicity

Ideal for small plants like lettuce and herbs which need relatively low quantities of water and nutrients since the water transfer capacity of wicks is limited by the natural effect of capillarity.

Not ideal for water and nutrient hungry plants like tomatoes or peppers or generally fruit-forming plants as it does not deliver a great amount of nutrients, nor lots of water.

The wicks and the growing medium are important as they are the only means to transfer water and nutrients to the roots. The wicks need to be efficient in absorbing water and be resistant to rotting. Efficiency can be improved when plants are placed directly on top of and close to the solution container so that water does not have to “travel” long distance (remember there is no water pump to deliver the solution).

The wicks can be anything fibrous of certain materials such as rayon, cotton, wool, nylon or polyurethane in the form of a string, rope, yarn, strips of fabric or felt. You can go simple, by using materials you have at home such as fibrous rope or strips of old clothing and blankets, even mop head strands.

How many wicks per plant depends on:

  • the plant you are growing
  • the growth stage
  • the humidity and temperature
  • how far apart the plant container is from the solution container as well as
  • the material and form of wick.

My suggestion is to start with 1 wick per plant for the small plants like herbs or 2 for larger plants like lettuce (remember, wick system is not recommended for fruit-bearing plants).

But water reaching the growing medium is not enough; the growing medium needs to be absorbent too in order for the water to reach the roots. Materials suitable here are coco coir, vermiculite and perlite.

Typical Problems of the Wick System

Algae, bacteria and other microorganism growth in the solution. Avoid using transparent containers where light can pass through for both the solution and the growing medium. Light encourages microorganisms to grow which can change the chemistry of the solution, reduce the efficiency of water transfer through the wicks and can cause root rotting, ultimately reducing yield.

Thirst. If you notice that your plants show signs of thirst or the growing medium is not wet enough, then try the following one by one:

  • Change the wick material if the wick itself is not wet enough
  • Increase the number of wicks per plant. Suggest to start with 1 per plant or if your plants are more water-hungry start from 2 wicks per plant and then level up.
  • Change the growing medium to something more absorbent.
  • Ensure that the water level in the solution container is filled up and remains high regularly.

Overwatering. Too much water in the growing medium surrounding the roots means that it is likely the roots are not oxygenated enough; if you see the growing medium being soggy you would need to reverse the list as above. Try the following one by one:

  • Change the wick material to something less absorbent
  • Reduce the number of wicks if they are too many per plant
  • Change the growing medium material to something less absorbent

Toxicity. A downside of the Wick system is that it does not deliver the nutrients evenly; you will get build-up of nutrient crystals to a toxic levels in places. So to avoid that it needs flushing with fresh water once a week. If you are consistent you will not get nutrient toxicity easily.

The positives of a Wick System 

It is not all doom and gloom with the wick systems. Studies (Ferrarezi and Testezlaf 2014) have shown that it can perform very well, even better than the NFT systems in some cases, as long as care is taken to not allow salinity increase in the grow medium which can reach toxicity levels. So if you are diligent to measure Electrical Conductivity (EC) and pH and act when those get out of range, the hydroponic wick system can be a very good one when labor and time is an issue.

What you need to build a Wick System

  • A nutrient solution container (ideally opaque not allowing light in). You can have a lid on with holes to allow wicks through.
  • A grow medium container
  • Grow medium (e.g. rockwool)
  • Wicks
  • Aerator is optional but recommended for better plant health and higher yields

In summary the Wick System Hydroponics:

  • Simplicity: very simple, largely maintenance-free except for filling up or cleaning the reservoir and the growing medium each time is required (which you would do in any type of hydroponic system)
  • Ideal for: small plants like lettuce and herbs and starting seeds and cuttings
  • Not ideal for: fruit-bearing plants like tomatoes and peppers
  • Efficiency: not great as it does not deliver large amounts of water and nutrients
  • What you will need: a solution container (preferably opaque not allowing light penetration), a growing medium container (preferably opaque not allowing light penetration), wicks; a use of an aerator is not required but if used it improves the plant health and increases yield
  • Experience required: not so. It is a simple system with no moving parts in its basic form.

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