Answer: BAsed on your description I'm not sure what is happening. Some of the taller sedums such as "Autumn Joy" will grow tall and then splay open. This happens if it needs to be divided (I would't think this is the case in the second year) or in some cases if it has been overwatered and/or overfed. These plants really do not require coddling with extra water or fertilizer (assuming average soil and precipitation) because by nature they are very thrifty. You will probably find that they go ahead and bloom nonetheless -- it is still a bit early to be expecting blooms on many types of sedum.
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