Answer: A purple orchid tree (Bauhinia variegata) should bloom purple, regardless of soil type or fertilizer used, but there is a white cultivar (Bauhinia variegata ?candida?) so I wonder if your order was incorrect? You might want to check with your nursery. Palm tree fertilizer won't hurt your orchid tree so if that's what you have on hand, go ahead and use it. It contains some trace elements that are not necessarily required by your orchid tree, so they will be wasted but their presence won't bother the roots of your tree.
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