Answer: Black spots can indicate a disease perhaps from overcrowding (poor air circulation) or excessively wet conditions, or even from lack of sufficient sunshine. Spectracide should protect unaffected plant parts from contracting the disease and pruning away affected leaves should also help. Spider mites tend to like dry, dusty places so hosing them off should discourage them. Applications of insecticidal soap can also help with control. I'm sorry you're having such a problem with your plants! The best approach is to choose plants adapted to the sunshine or shade available on your patio and plant them in good soil (which you've done) making sure the containers drain well. Try to water the soil, not the plants. If the leaves get wet it is important they are able to dry out before nightfall so water in the mornings when at all possible. Wish there were something more I could suggest! Good luck with your container garden.
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