Play it child-safe year-round with species such as astilbe (Astilbe spp.), hardy in USDA zones 3 to 9, Cleome (Cleome hasslerana), hardy in USDA zones 2 to 11, daylily (Hemerocallis spp.), hardy in USDA zones 4 through 9, phlox (Phlox paniculata), hardy...