Answer: August is a stressful time for plants so it would probably be better to wait until September (unless they are in standing water.) Also, you should not work clay soil when it is still wet and sticking to your shovel.
With a heavy soil, it can be helpful to plant on a slope or to make a slightly raised bed. Also, avoid planting at the bottom of a rise or slope as that will be a naturally wetter area.
Before you do your replanting, you should run some soil tests to check fertility and pH levels. Use the test results to determine if you need to fertilize or add lime. These can be adjusted when you prepare the soil for replanting.
With a raised bed, you do not have to use formal edging if you raise it only a few inches. Loosen the soil down six inches for annuals or twelve inches for perennials and add organic matter such as several inches of compost, plus a small amount of coarse sand or fine grit. Then set your plants being sure not to plant them too deeply. Using an organic mulch year round will help add organic matter on an ongoing basis.
Blooming performance will depend on many factors, but the hot weather of August along with dry soil can limit blooming on many plants. Regular deadheading can help prolong blooming, as will selection of varieties noted for their extended bloom season. Certain perennials for example will only bloom for a week or two, while others may bloom a bit longer initially or might rebloom later in the season. Cool season annuals will stop blooming when the summer turns hot, too.
I hope this helps you trouble shoot.
Q&A Library Searching Tips