Answer: It sounds as though your plant is showing some distress over being transplanted. It sometimes takes a while for the stress to show up and the first thing a plant will do is abort flowering in favor of retaining its energy for new root growth. The flower spike may open later in the summer or it may die down before it ever opens. Yucca plants are best planted in the fall so they have all winter to become established before producing the flowering stem which remains on the plant most of the summer. If the stalk collapses, cut it off. Next spring it should produce a healthy new flowering stalk.
Best wishes with your landscape!
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