Answer: Unfortunately I am not certain if you mean the shrub called butterfly bush (Buddleia) or perennial called butterfly weed (Asclepias) or something else entirely. In general, you could use a general purpose fertilizer such as 10-10-10 annually in the spring. A slow release fertilizer or a general purpose granular would be fine. Read and follow the label directions for how much to use. I hope this answers your question.
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