Answer: Your zip code (64836) places you in winter hardiness zone 6A or the coldest part of zone 6. Your summer heat zone is between heat zone 7 and zone 8. So you will need plants that are wind tolerant for dry soil and full sun in hot summer weather and fairly cold winters. Spring flowering bulbs such as crocus and daffodils are an excellent choice for a durable, low maintenance, long term planting. Most flowers are not well suited to that type of situation as they are not able to outcompete weed grasses and most would need some supplemental water during the month of August if not more so. If you really want to try flowers, you might look at purple coneflower (Echinacea purpurea) and possibly daylilies (Hemerocallis) or the perennial oriental poppy (Papaver -- this goes dormant in midsummer so would not need watering then) as these are fairly sturdy and longlived perennials.
But for best performance and lower maintenance I would suggest you work with shrubs instead, in part because they are longer lived and generally require less work than flowers. Some extremely low maintenance and sturdy flowering shrubs to consider might be Rosa rugosa, lilac, forsythia, old fashioned spirea and flowering quince (Chaenomeles). If you would like to use an evergreen as well, look at the assorted named varieties of juniper. Keep in mind that the first year or two you will need to keep the area weeded and mulched and deep water the plants in dry spells until they become thoroughly established. After that, they should not need supplemental water except in a case of severe drought.
Your local professional nursery staff may also have suggestions based on a more detailed understanding of the planting site and your design goals, but this should help you get started.
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