Passive Hydroponics – Submersion and Wick Hydroponics

Probably the Least Technical Hydroponics System

There are few drawbacks to growing plants without dirt. Passive hydroponics require very little effort after the hydroponic garden has been set up. Checking the water levels and testing the pH of the water occasionally is basically all that is needed. Passive systems do not use pumps or tubing to deliver nutrients to your plants. The plants circulatory system or a wick for absorption is how the plants obtain their food.

Wick Hydroponic System

The wick system uses cotton wicks, like those for lanterns, to feed your plants. The plant’s roots are loosely wrapped with the wick leaving a long section of the wick submersed in the nutrient water. The wick pulls the fluid upwards drenching the roots. The plant can then feed itself absorbing what it needs directly from the wick. This completely passive system does not require electricity.


Another type of passive hydroponics is submersion hydroponics. In this type of system, the plant’s roots hang into the nutrient water. Plants are supported on a raft type platform most often Styrofoam. Small holes are cut in the Styrofoam supporting the plant while the roots dangle in the water.
Water levels will need to be check regularly especially when it is warm. An aquarium bubbler will be needed to provide oxygen to the plant roots. A fish aquarium, painted on all side with a small corner left unpainted, will allow you to check the water level without disturbing the plant’s raft. If the aquarium is not painted or covered, algae will grow and suffocate the plants’ roots.


By using passive hydroponics, the time required to tend your garden decreases. If the power goes out, plants growing by the submersion method will be safe for a few days before they start to suffer. The wick system will not suffer from a power outage unless it is winter where you are using grow and heat lights to fool the plants into thinking it is summer.


Both the submersion and wick passive hydroponic systems share one common disadvantage. The roots can become too wet due to constant exposure to water. If you design your holding tray so that it can be lifted out of the water without harming your plants, you can let the roots drain completely on occasion.
This is usually sufficient to prevent root rot. Also, with a wick system when using grow and heat bulbs a power outage of more than a few hours will result in the loss of the garden.

Recommended Plants

Using the wick method, you can plant a larger variety of plants than you can with the submersion method. Wick system plants can include tomatoes, peppers, strawberries, kale, cabbage and many other types of heavier plants. The submersion method works best when lightweight plants like lettuce, herbs, cherry tomatoes and spinach are chosen.

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