Propagation

Hydroponics is particularly suited to plant propagation. The conditions required for good germination and rooting are easily met; clean, pest and disease free conditions and a growing medium with good drainage and moisture retaining properties. Any of the granular media described in the Media or Substrate section above can be used. Conventional propagation materials such as peat substitute can also be used and the plant transferred to a hydroponics system when growing on. Hybrid solutions are possible; starting by planting into a peat-free expanding pellet and transferring to a rock wool cube or pot later. An open structured pot as used for aquatic plants is often best, as it'll allow the roots to grow through the holes later.  Rock wool is a favourite material as it matches our requirements very well. Its moisture and air retaining properties make it ideal.  It's available in 1/2 and 1 inch cubes with a small indent in the top to take seed or a cutting.

The cubes are wetted with clean water to the point of saturation and then left to drain for a minute of so on newspaper. Once you get used to the amount of water required you won't need to do this but it's surprising initially just how much water is required, so it's best to super-saturate and then drain.

One or two seeds are dropped into the indents and the cubes are transferred to the propagator where a temperature of 20-24 degrees C is maintained. Don't forget to use labels to identify the seedlings later.

The vents of the propagator lid, if present, are initially closed to keep the atmosphere humid. Once the plants have germinated and leaves are present ventilation can be increased to reduce the risk of mould growth which may harm the seedlings. If the lid has no vents then it can be propped open a little to allow air to circulate. At this point the seedlings should be moved to a bright location so that they don't grow tall and thin.

Watering will be required as the increased light, ventilation and plant use encourage the media to dry out. No nutrient is given until the first true leaves appear and then only a weak mix is added, building up from 25% - 50% to full strength over a 2-3 week period.

Seeds can also be sown directly into pots containing granular mixes of perlite and vermiculite or clean sand, although watering presents the problem of avoiding washing the seed too far down into the pot. These media are particularly suited to root crops such as carrot or beet. In this case the media is much deeper to avoid having to move them later.

Cuttings can be treated in the same way with the stem inserted into the media. Rooting hormone can be used but is not usually necessary. If aeroponics is used the stem of the cutting can be allowed to poke through the media so that it is exposed to the spray. The high oxygen availability using this method is particularly beneficial for rooting.