This is the time to really enjoy your garden. The major work of digging, adding organic matter, transplanting and creating new beds is finished and with just some weeding and deadheading to keep up with now is the time to just sit around and enjoy the fruits of your labour. These numbers refer to the macronutrient content of the fertilizer.
P stimulates early root development and is necessary for flower, fruit and seed formation.
K strengthens stems and leaves, promotes vigour and disease resistance. Some formulations contain micronutrients such as boron, copper, iron, manganese, molybdenum and zinc. These will be listed on the bag. That depends what you want it to do. Many are slow release and will give a continuous feed for the duration of our growing season.