Answer: The annual lobelia needs morning sun or bright dappled light all day and will not tolerate hot afternoon sun, it also tends to decline when the weather turns hot and humid. Based on your description it might have had too much sun, in which case moving it would help. However, it might also have a disease problem such as mildew which occurs under certain weather conditions. This can sometimes be prevented by keeping the plant in a location with good air circulation, not wetting the foliage if you water, and cooperative weather.
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