Osmocote was designed for and is mostly used professionally for plants that are in some form of a container for example a seedling tray, a grow bag or a pot, and for that reason these application methods focus on containerized plants. As a gardener or hobbyist the best advice will be to understand how Osmocote works and to devise a method of application that best suits your situation. Osmocote is very safe so don’t be scared to experiment with different methods. As long as you don’t damage the coating, you can’t do much harm.
Back to the professional container plant grower:
The best and most cost efficient method will be to mix the Osmocote into the growing medium. This can be done by a specialized growing media mixing machine, a concrete mixer or even by hand. It will all depend on your set-up and the scale of operations.
It is important to note that we do not suggest that Osmocote be mixed into big heaps using a bulldozer since it will be difficult to mix it evenly.
Osmocote can also be top dressed to already potted plants. Here it is important to make sure that the Osmocote can’t fall out of the pot or plant bag during watering or if the plants are blown over during a wind storm. It is also important to place the prills close to the dripper if you are using a dripper to give water. It is often safest to work the prills about 2cm into the top of the growing medium close to the dripper when top-dressing. Always make sure all irrigation comes from the top.
One of the most effective and simplest ways of applying Osmocote is when plants are being re-potted or potted up. Simply throw the Osmocote onto the medium in the new pot, cover with about a centimetre of growing medium and plant the plant on top of it.