Wicking bed – plants wick up the water they need

In aquaponics you can grow up to 120 different types of vegetables, all at the same time, if you want to, but we are often asked: What about onions, carrots, and sweet potatoes?

A wicking bed will be your answer. Although not strictly part of your aquaponics system, you can use nutrient rich water from your system to fill the waterpipe in your wicking bed. Also use all the leaves and roots that you don’t use from your aquaponic system to make the compost for your wicking bed.

It will not be possible to make it part of your circulating system as all the water is basically used by the plants.

The principle is that the water is “wicked” from the bottom of a trough into the root area of the plants.

How to do it:

  • Build a trough, it can be anything that can hold water; plastic, tarpaulin, fibreglass, an old bath.
  • Lay a pipe at the bottom, diagonally across. At the bottom of the pipe there must be holes for the water to run out. Cut slits in a piece of PVC pipe, for instance.
  • Pipe has 90˚ bend with the end of the pipe sticking out 10 cm above the rim of the container.
  • Fill the bottom of the trough up to 10 cm with gravel.
  • Put some shade cloth over the gravel and up the sides of the trough. (60 to 80% thickness – water must be able to go through it)
  • Make a hole in the side just above the shade cloth and put a pipe through for overflow in case of over-watering or rain.
  • Get your soil and compost mix ready and fill from the shade cloth up to 30 cm.
  • Plant your onions etc and put water into the gravel through the end of the pipe sticking up. If the water level in the pipe is the same as the gravel level; then everything is hunky dory. That is all you have to check for about once a week.