Landscape design tip
There is a major problem with growing flowers in all day full sun here on the prairie. The environment in full sun is very harsh. The problem is not the temperature of the sun. It does not change. The sun is no hotter in the afternoon than it is in the morning, but the environment in full sun is harsher in the afternoon than in the morning. The air temperature is hotter. The relative humidity is lower (dryer) and the drying wind blows stronger. It is hotter, drier and windier. The challenge in growing beautiful flowers here on the prairie is then to locate and plant the flower beds in a way that will make the environment less harsh. The best way to accomplish this is with a windbreak. If we slow or stop the wind we can reduce its drying effects, slow the rate of evaporation from the surface of the leaves, and raise the relative humidity in the microclimate around the plants. The environment around our flowers will be much less harsh.
We do not need to plant giant walls of evergreens to provide a windbreak. Our annuals will be dead when winter comes so deciduous plants will work just fine. Remember our dominant winds in the summer are from the south, southwest. To protect our flowers we need to plant windbreaks on the south to southwest side of our color spots. The plants used for these "windbreaks" can be anything a little taller than the flowering plants we will plant in front of them. Medium size shrubs, ornamental grasses (annual or perennial), and several taller growing annuals that are heat and drought tolerant work well as windbreaks.