Answer: Based on your description I am not certain what would cause this, although exposure to cold temperatures (below 50 degrees or so -- and I notice there have been some nights near freezing recently) is damaging and might affect the bracts that way, as could over or underwatering. Although you would not want to overwater this plant and it needs a well drained soil, it does need adequate soil moisture when growing in a container. Basically you do not want to allow it to go bone dry or have it saturated/sopping wet either. When the soil surface is dry, water it thoroughly. In cool weather, or cloudy or rainy weather you may not need to water as often as you will in the heat of summer. I hope this helps.
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