Is that area full sun, partial shade or full shade? I'm assuming it is
zone 5? For all summer blooms I'd go with an annual. They bloom longer than most perennials. And you only have to
plant them once a year. I have great success with zinnia. They bloom and bloom and give lots of colors and they are great in cut
flower arrangements too. Plus they develop lots of
seeds that you can use to
plant next year. I think it's a win win with those. And I've never really had to do anything to keep them
growing.
Why don't you get some of those drip hoses and put them on a timer. Then she wouldn't have to worry about watering the
flowers. It would be done automatically.
If the area is wind protected I love peonies but they only bloom for about 2 weeks in the
spring and then you have to wait until next year for more blooms.
If you get the watering taken care of then once a week might be plenty of time for caring for some hardy
roses. Just a thought.