No, frost-killed gladiolus will not come back. If you have noticed the blooms of your gladiolus turning black, that means they have died and this is an indication of having suffered from a cold-winter. Frost also affects other parts in your garden like greenhouses. Gladiolus are usually used as houseplants to keep the rooms cool in summer and the flowers bloom during warm winter months. However, if your plants suddenly go dormant and don’t start to bud until fall or early winter without notice they may be frosted due to cold temperatures outside and that can cause plant damage like blackened leaves or dying stems.