Answer: In your area, it is very difficult to overwinter perennials in containers. The reason for this is the roots are not as well insulated as they would be when planted in the ground.
For this reason I would suggest you plant annuals such as marigolds, salvia, calibrachoa, dianthus, the small seed dahlias, sweet alyssum, petunias, and dusty miller.
If you want to overwinter your plants, you might try mandevilla, tropical hibiscus, lantana, and cannas. The first three can be brought indoors as houseplants, the cannas must be dug and stored for the winter.
On a hot and sunny deck, you will have better results using as large a container as possible as it gives better insulation from the heat for the roots and it also stays moister longer between waterings. The containers must have drainage holes in the bottom. Make sure to water as needed to keep the soil evenly moist like a wrung out sponge, not sopping wet and not dried out. Also, use a good quality potting mix formulated for container planting. Good luck with your flowers this summer!
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