Answer: Calla lillies (Zantedeschia) are originally from South
Africa and do not tolerate cold winter weather, so they're perfect for indoor growing. As a potted plant, the rhizomes are usually started into growth during the fall to force blooms during the winter. They may also be planted in spring for summer bloom. During their growth period
they prefer cool household temperatures, rich soil and ample
moisture. After blooming, when the leaves begin to yellow,
the plants should be rested by gradually reducing water,
allowing them to dry out. Callas need a rest in order to bloom again. It is a good idea to repot into fresh soil each year (usually after the dormant period), because callas like a good rich mix. I suspect temperatures have been a bit too warm for your plants which is why they're not looking as robust as they could. They may also be on the verge of going into dormancy after flowering. I'm afraid they only flower once before needing a rest so the flowers will not reopen. Hope the above answers all your questions!
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