Potting mixtures

There are a variety of potting mixtures. Those designed for terracotta pots are full of organic matter to retain a lot of moisture. Some potting mixes are unusual such as the lumps of bark used to pot a particular type of orchid (Cymbidium) that grows on tree trunks and lives on the moisture and nutrients that run down the bark. This orchid would not survive in ordinary potting mix or soil because it needs excellent drainage that is provided by the coarse bark.

You can make your own potting soil. Start with garden soil, add coarse river sand to create a free-draining soil and coca fibre to retain some of the water. These components should be in a ratio of one third of each. This soil won’t go hard and the roots can penetrate it easily.

The soil used for raising seeds is different. Seedling raising mixes are pasteurised to remove all the organisms such as harmful bacteria and fungi. This is different to sterilisation which kills all living organisms in the soil.

Remember when handling potting and seed-raising mixes be careful as it may cause irritations or respiratory problems especially if you have allergies, or are susceptible.