A grow bed is the place where the plants are kept and the water is applied to the roots. Some grow beds use special grow bed medium like gravel or expanded clay pellets, some just use the water alone, and some use nothing at all – the roots are hanging in the air.
Grow beds need to do 4 things. Provide support for the plant so it can grow without falling over. Provide water to the roots, provide nutrients to the roots, and provide oxygen to the roots. In an aquaponics system, the water and nutrients happen at the same time, so that’s covered. The other thing we need to make sure we do is provide oxygen to the roots. This is often done by exposing the roots to air.
Which system you use will depend on what you want to grow, as some plants like some systems better than others, what materials you have available to you and your budget, and most importantly, what tickles your fancy. Some types just appeal to some people more than others.
The primary grow bed types that are usable to us include the following:
- Nutrient Film Technique (NFT) – The roots sit in shallow trays with a very thin stream of water flowing past the roots.
- Deep Water Bed
- Raft systems – large shallow trays of water with foam sheeting floating on top with holes for the plants in baskets.
- PVC tubes – The classic rows of horizontal PVC piping with holes cut on the top with plants placed in baskets in the holes.
- Flood and Drain (Ebb and Flow) beds – waterproof planters containing an aggregate which are periodically filled and emptied.
The placement of your grow beds isn’t terribly important as long as you’re mindful of where the water will drain if the power goes out. This usually means placing the growbeds above the aquarium so water can drain back into the aquarium.
Placing a growbed immediately above the aquarium is convenient, especially if the growbed is of similar size as the aquarium. You could also place the growbed(s) in a nearby shelf as well.