I bought a beautiful Mandevilla plant about one month ago. It’s in a large pot and was doing beautiful, but now it’s starting to turn yellow. I might have over watered it. I live in Phoenix, so it’s getting hot. Does that have something to do with it?
The heat and sunlight could definitely be affecting it, but typically yellowing leaves does mean the plant got too much water. Mandevillas need sandy, well-draining soil, support and some shade. Cut back on the water, cut off any dead leaves and double-check your sunlight situation.
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