Seven-son flower whorl.Betty Cahill, Special to The Denver Post Practically Perfect Plants: These plants perform almost perfectly in Colorado gardens, with a long bloom period (nice foliage counts, too), less fuss and maximum enjoyment. Agastache may be tricky to pronounce — “a-gas-ta-key,” or “ag-a-stack-ee” — but these perennial plants are winners for gardens that thrive on tough love and less water.