if she wants short try bulbs, and stagger them so that she will have something in bloom the whole season...from crocus and daffs in march to gladiolus and lilies in august. Try adding rocks for interest or an actual fountain.
You could also try perennial vegetables...like rhubarb, asparagus, strawberries. Or herbs! Thyme, mint, rosemary, garlic, oregano. (mint will need to be planted with a bottomless pot around it as it will take over in short order and is tenacious)
Depending upon the sun try hosta, bleeding hearts, lady's mantle; these all like shade.
if height isn't truly an issue try lilacs (slow growers in NH) as are forsythia which scream in bright yellow around April. There are also azalea types that loose their leaves for the winter.