|These cormous perennials are grown for their showy spiked flowers, which open from the bottom upwards. Foliage is strap-like and vertical. Gladiolus look best when planted in large groups. It is common to stake them. Soil should be fertile and well drained and light may be full sun or partial shade. Hardy in zones 8-10, they may be planted in other areas as annuals or even protected with a thick layer of mulch. For best flowers, fertilize with a high potash fertilizer once spikes reach about 1/2 their height. If glads are not hardy in your area, remove them from the ground roughly 6 weeks after they have finished blooming. Separate the new corms from the old and throw the old ones away. If fungus is a problem in your area, you may want to treat corms with a fungicide prior to separating them.