Answer: Potentilla and the small summer blooming spireas are often suggested for sunny locations; the flowers on any plant will normally fade and turn brown once the bloom season has passed.
Unfortunately, I do not know of any low maintenance shrub that will bloom all summer long. You might like the groundcover types of roses that bloom over a longer period, but they often need spraying for Japanese beetle control so that is not really low maintenance. Butterfly bushes would bloom over a long period, but they are not of the tidy appearance and small stature typically associated with a foundation or walkside planting. So there may not be an ideal solution for you.
Watering is always a matter of judgement and sometimes trial and error. Clay soil can hold a great deal of moisture and hold it over an extended period of time, but once it dries out it can be difficult to rewet it. Watering is usually better done as a slow deep soaking less often rather than as a daily sprinkling. The rule of thumb is to apply the equivalent of an inch a week, taking into account any rain as well. Newly planted shrubs may need slightly more frequent watering while they are becoming established. The nursery supplying the plants may have their own suggested routine for this, especially if there is a warranty on the plants.
Clay soil can be a good gardening soil if it is amended and worked properly. I would suggest for starters that you contact your county extension. They should be able to help you run some basic soil tests to see how "good" or "bad" your soil really is, then determine what amendments are needed to optimize plant growth and survival. They should also be able to suggest some shrubs that would survive in that location and soil with the minimum effort on your part.
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