Hydroponics is a gardening method whereby plants are grown not in soil, but in water. Plants that will usually grow in soil are grown with their roots in a nutrient-rich water solution. A number of different substrates are used to support the plant roots, including expanded clay aggregate, gravel, perlite, vermiculite or polystyrene. Hydroponics is now used on a large scale, commercially, all over the world. But hydroponics systems can be used on a small scale as well as on a larger one. A hydroponic system or some variation thereof could be a good solution for a home grower – it could be something to think about and consider when designing your own domestic polytunnel.
There are a number of different hydroponic systems that could be of use in domestic polytunnels. The simplest involve just a tub or tank, or even just a plastic bucket topped with a lid in which holes have been cut for each plant. Oxygen is key to plant success and so if aeration is not provided, the nutrient-rich solution below the plants is kept low enough that each plant can still get enough oxygen to thrive. An upgrade for these simplest systems is a pump to keep water aerated, like those found in aquariums. Another relatively easy hydroponic system to implement in a domestic polytunnel is a continuous flow solution culture. In these systems, nutrient water is set up to continuously flow past plant roots through a nutrient film in a root mat. This system can be used to create a vertical garden to grow a variety of leafy greens.
While further study should be undertaken before you decide on a hydroponic system in your polytunnel, there are certain benefits which could make this a worthwhile type of growing to consider. Hydroponic systems require less water than traditional, in-soil growing methods and so can be an excellent solution for drier areas. Productivity can be high and, when the plants needs are optimally met, the speed of growth can be increased. If you are interested in hydroponics, the next question to ask is – where will the nutrients in your water come from? Another option, explained in more depth in the article on the subject, is to create a system in which this need is catered for not from outside but from within the system – aquaponics – in which you can grow both plants and fish in your polytunnel.