Answer: This plant will tolerate more sun if it is grown in an evenly moist, organic soil and in a cooler summer climate. In a pot, especially, it will be subject to not just general heat but to the the soil overheating and drying out quickly as well. In a full sun location it is also subject to additional reflected heat off of the building so the overall combination is a bit overwhelming -- and on an elevated deck, excess wind can sometimes make the situation even worse.
Morning sun would be the maximum I would recommend in a hot summer area such as yours, so it would be a good idea to make sure it is in a generous sized tub to help insulate the roots, and then either move it or shade it as best you can. Generally a full sun location on a wall would be one that is open to the south, while a northern wall would be shady almost all day. Perhaps you can shift the plant to a less sunny side of the deck. An eastern exposure in morning sun will be cooler than the western afternoon sun. Also, there is shade cloth made for greenhouses (large nurseries and greenhouse suppliers would have it) that can be fashioned into an awning. This would help your deck stay cooler and more comfortable too.
Last but not least, make sure you are not overwatering the plant. Use your finger to make sure the soil is not too wet, as this can cause somewhat similar symptoms as underwatering. Overfertilizing can also cause foliar problems, so if you use any of that make sure to read and follow the label instructions carefully.
I hope this helps you troubleshoot.
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