Answer: Any general garden fertilizer that's high in phosphorous (the middle number) will encourage blooming. Use something like a 5-10-10 according to label directions. The amount of fertilizer used per plant will vary with the size of the plant. It is much, much better to err on the side of too little fertilizer than too much. A very small plant will take about 1/4 cup. A very large shrub will take 1 - 2 cups spread around the drip line of the branches (not next to the trunk).
Best wishes with your garden!
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