What is hydroponics?

Hydroponics is a method of growing plants using a nutrient solution and without the use of soil. Much of the sales and vegetable produce sold in supermarkets today is grown using this method.

The method is not new. The idea of growing plants in water has been around for over 2,000 years and has been recorded in Egyptian hieroglyphics. The hanging gardens of Babylon and the floating gardens of the Aztecs are two examples often cited.  Hydroponics is also a method for the future.  When the first space mission to Mars departs from the Earth, it is almost certain that much of the food for the lengthy trip will be grown on board using hydroponic systems and artificial lights.

What are the benefits of growing plants hydroponically?

The key benefits of growing hydroponically rather than in soil are:

• Less waste: The nutrition levels fed to plants can be precisely controlled so there is little wastage of water or minerals compared with conventional agriculture.
• Better yields: As everything is controllable, growing conditions and nutrient levels can be adjusted to optimise plant yields for harvest. This also leads to more predictable yields.
• No soil means there is more control of pests and diseases. It also means that plants can be grown in places there is no soil. Such as indoors or on a spacecraft on its way to Mars!

There are also some downsides:

• The energy costs of producing the minerals needed by the plant are higher than allowing the plant to extract them from soil.
• Since you are in control, if you make a mistake in the nutrient make-up then a plant may not get everything it needs to grow.

Generally the downsides are massively outweighed by the advantages.

Hydroponics are often closely associated with other techniques for growing plants, such as the use of artificial light to supplement or totally replace sunlight and the use of  heating/cooling to maintain air temperature at the optimum. Whilst these other techniques can be used with soil based techniques, the use of hydroponics ensures that plant yields are maximised

What makes up a typical hydroponic system?

Let’s take the example of a totally indoor system with no or little sunlight as found in an appartment. We need to consider:

• Lighting – artificial lighting will be needed to get vigourous plant growth
• Temperature – the air temperature and ideally the temperature of the plant roots need to be controlled using heaters and/or cooling.
• Nutrient solution – different plants may need different solutions and even the same plant may need a change in solution as it moves from vegetative growth to its fruiting stage.
• Growing medium – plants need something to support their root systems so they remain upright.
• Support – for vine plants such as tomatoes, the growth needs to be supported in some way with twine or trellising.
• Pollination – if a plant is not self-pollinating then bees/insects or mechanical equivalents are needed to ensure the plant produces fruit.