As soon as the bale of a plant is completely penetrated by roots it is time to give it more space. The same applies when roots begin to grow out of the pot. The new vessel should be three to four centimetres taller. If it is too large, the plant concentrates on setting up new roots rather than on the desired flower and shoot formation. White sites at the surface of the soil are a sign that the plant needs fresh soil. This is a result from too hard water or too much fertilizer.
If the vessel has been used before, you should clean it with hot water and brush it to prevent any transfer of fungi and bacteria. Does the pot have a drainage hole? If so, you can put a piece of crock on the ground so that soil does not get out from the hole. If there is no hole, it is better to build drainage to prevent waterlogging. You can do this by using gravel or expanded clay. A slice of fleece can be placed between drainage and soil so it does not mix up. After this is done you can fill the pot with some fresh flower soil. Keep in mind that bale and shoots should be placed two centimetres below the rim of the pot.
Now take out the plant from its old pot. The bale can be removed fully by tapping the pot, whereas stubborn plastic pots may need to be removed using scissors. Before repotting the plant, its bale must be free of old soil. Dead root parts should be cut off with scissors or a secateur.
Place the plant in the middle of the new pot, fill in soil from every side and press the soil firmly in. Remember to leave a free space of two centimetres from the rim of the pot. Last but not least water the plant sufficiently, and if required add some more soil.