On various garden forums, I occasionally see questions about which glads are really winter hardy. Aside from a handful of European species, some of the South African ones are hardy, as are some of the gladiolus cultivars (though they are not usually advertised as such). G. oppositiflorus ssp salmoneus is a winner in all respects--it is an attractive species with elegantly shaped flowers, it is easy to grow, propagates well from cormlets and will produce copious quantities of seed if pollinated, and is winter hardy. It has the form of the larger gladiolus hybrids but is not so tall as many of them are, thus it is more suited to smaller gardens. It will bloom in summer, though some of mine (the ones I stored inside last winter as "insurance"--turned out this was not necessary as those left in the garden did fine) bloomed late this year because I planted the corms out late. Ellen Hornig reports in her catalogue that it has survived outside for her for years in (frigid winters!) upstate NY, so its got what I consider a real seal of approval for cold hardiness in the north!