Blue Isle Large Flowering Gladiolus 10 LOVELY "Blue Isle" Gladiolus Bulbs Will bloom 60 - 90 days after planting ~ plant in 2 week intervals for blooms starting in summer & continuing thru fall. Gladioli bloom best in full sun, but will tolerate partial shade; Height: 36-50 inches Hardy in zones 8-10, elsewhere dig and store inside for the winter* (see note in description below). LARGE 12/14 cm bulbs (flower bulbs are measured in circumference).