Modern potting mixes often feature large amounts of organic materials such as composted pine bark. Such mixes can gradually break down and also run out of nutrients, particularly if they are required to last beyond 12 months. If you have a pot plant that is looking a bit off colour or not growing well then this would be a good time to repot.
When should I repot my plant?
Most types of plants are producing lots of new root growth coming into the warmer months of the year, making this a perfect time to move them up into a larger pot size. If you are seeing new leaf growth above the ground then you can be sure that the plant is expanding its root system. The emergence of lots of white roots from the drainage holes of the pot is another obvious sign to look for.
Plants that have been in the same container for any length of time will usually have roots curling around the base of the pot. Remove the plant from its pot and gently tease out any roots that are curling. In such cases it is a good idea to tease them out and cut off any deformed roots and at the same time reduce a similar proportion of foliage to compensate.
Australian Standards for potting mixes
For best results it is worth investing in a medium that conforms to the Australian Standards for potting mixes. There are two grades, with the premium type containing added fertiliser to sustain growth for at least a month, while the regular grade requires fertiliser to be added at the time of potting. It is usually a good idea to add some extra slow release feed when repotting depending on the type of plant, but also consult the directions on the label with regard to fertilising. When you have finished repotting always water the plant in thoroughly to ensure that the potting mix is evenly wetted.