Hydroponics – Cultivating without soil

Cultivating plants without soil is called hydroponics or hydroculture. Many plants can be grown in this way, and the technique has become popular in recent years. Specially cultivated plants are available, or you can ‘convert’ one that has been compost-grown in the normal way, but don’t risk a rare specimen. Many plants can be grown successfully without soil. The plant roots are anchored in a pot containing clay granules and grown in a measured solution of water and fertilizer.


Equipment for hydroponics

There are two types of container you can use for hydroponics. The first is a watertight plastic planter used with a separate water gauge. The gauge has a floating marker which rises and falls with the fluctuating water levels, indicating minimum and maximum levels. You can actually overwater a plant by constantly topping up the water to the maximum level. When the marker falls to minimum, don’t top up the water straight away. Letting the roots ‘breathe’ for three or four days will ensure that the water stays fresh Planting up single containers

Use young, healthy specimens or well-rooted cuttings. Clean all traces of compost off the roots by soaking the rootball in a bowl of tepid water and then rinsing it under running water. Take great care when doing this to avoid damaging the root system. Next, fill the container with a shallow layer of washed granules, and position the water gauge at the side of the pot. Hold the plant on top of the granules and spread out the roots. Gradually add the rest of the granules to the desired level. Add the correct strength solution until the water gauge is at maximum.


Enclose the plant in a polythene bag for the first few weeks, to conserve moisture, and keep at a constant 20°C (68°F). Gradually acclimatize the plant by opening the bag for a few hours each day, before removing the bag entirely.

Plant up the inner pot of a double container in the same way. (Pineapples give excellent results when grown without soil. Start one off by simply slicing the top off a fruit.)

The second type is more expensive, and has a double container complete with a built-in water gauge. The inner container, with slits or perforations in the base, holds the granules and the plant. It is suspended inside the watertight outer one which contains the water and fertilizer solution. The roots grow through the slits into the outer container.

You will also need to buy the growing medium: granules of expanded clay aggregate (often called ‘plant pellets’) and a special slow-release fertilizer in powder or pellet form. Follow the manufacturer’s instructions for mixing and adding the fertilizer. Every few months, drain off all the solution and replace it with a fresh mixture.

Plants to try hydroponics with

Most plants can be grown without soil, with the exception of orchids, cacti and succulents. Fleshy plants such as African Violet and Begonia Rex should also be avoided. For the best results, choose from the following:

Preparation and planting

Plants grow well in plant pellets’, small granules of baked clay treated with slow-release fertilizer. Growing plants without soil is easy if you follow these simple instructions:

  • Knock out the plant from its pot and loosen the compost round the rootball without damaging the roots. Soak in a bowl of tepid water.
  • Tease out the roots and then wash them gently under tepid running water. Remove all traces of compost to avoid contamination.
  • Fill the container with enough granules to raise the plant to the correct level. At the same time, position the water gauge.
  • Place the plant on top of the granules and spread out the roots. Hold the plant firmly in position and add more granules.
  • Continue to add granules until the container is full. Pour in the solution of water and fertilizer until the gauge reaches maximum.
  • Cover the plant with a polythene bag for the first three or four weeks.

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