Peters Fertilizer is a commercial plant food and there are different formulas of this brand as it is often used by professional growers for different crops. It is a fertilizer that is mixed with water (warm water works best) and then applied to the leaves or around the soil of the plants. The dosage depends on what you are feeding and how often you plant to fertilize. My advice is to visit the website of the company to find the correct dilution. In general, I would not fertilze plants at the time they are transplanted. Lily of the valley plants have underground stems that are similar to bulbs. They will not need fertilizing when transplanted and this fragrant bulb is such an enthusiastic grower I would not fertilizer it all - in fact many gardeners regret planting lily of the valley bulbs as they spread very fast and can crowd out other plants.  May your lily of the valley grow only where you want it and enjoy the fragrant blooms. Keep growing, Marianne Binetti