I have 6 deck planters in the sun most of the day. They only have about 6" depth of soil. This summer has been so hot and dry, and the salvia I planted looked so bad I pulled them up. Looked like black spot disease. There aren't any bedding plants this time of year, but I would like to plant something in the pots now. Is there any seed that could germinate in this heat (90's) and then bloom all fall? It would need to be short, not over 10". I'd be willing to start them indoors where it is cooler, but prefer to direct sow outdoors. And how do I kill off the black spot disease in the soil before planting? I never sprayed the salvia for fear of hurting the bees that liked to visit it.