Newly planted shrubs need proper care to ensure they get a healthy start. Although fertilizer is important for growth, do not over-fertilize your new shrubs because this may damage them. Too much fertilizer can also contribute to disease and winter injury. Allow your newly planted shrubs to establish in the soil before you fertilize. This will ensure the root system is growing normally, which will enable them to receive the fertilizer and use it effectively.
Fertilize shrubs planted in the fall for the first time the following spring. If the shrub was a 1-gallon size shrub, use 1 tbsp. of fertilizer. If the shrub was larger than 1 gallon, use 2 to 3 tbsp. of fertilizer. Sprinkle fertilizer evenly over the entire area beneath the shrub, extending the fertilizer out up to three times wider than the branches of the shrub.
Fertilize shrubs planted in the spring for the first time approximately eight weeks after the spring planting. Use slightly less than 1 tbsp. of fertilizer for a 1-gallon shrub and slightly less than 2 tbsp. for a larger shrub. Sprinkle the fertilizer evenly over the soil under the shrub, extending it out in the same fashion as in step one.
Water the soil under the shrubs well immediately after you fertilize to activate the fertilizer and help it to soak into the soil.
Fertilize established shrubs in subsequent years by applying between a half cup and 1 cup of fertilizer to the soil around the shrub. Fertilize shrubs either in the spring while the shrub is still dormant or in the autumn after the season's first frost. Autumn fertilizing will encourage more prolific shrub growth the next growing season than spring fertilizing.