Plant them in spring at about 10-16 cm deep in fertile, well-drained soil, in full sun, on a bed of sharp sand to aid drainage. For frost-hardy to half-hardy gladioli apply a high-potash liquid fertilizer when the flower spikes reach one-third to half their final height and repeat every 10-14 days until 3 weeks after flowering.
In frost-prone areas lift them when the leaves turn yellow-brown and lay them out on greenhouse staging to dry before cleaning off the soil and cutting back their old foliage and flower spikes, around mid to late autumn, snap the corms from the stems, dip in fungicide and dry for 14 days. If you want to propagate gladioli, now is the best time to do it by separate any new corms that have formed around the old parent.
Store all the corms over the winter in a cool, dry place. Keep them in paper bags, labeled with the variety name. In late winter or early spring, prepare them for planting them inside. The corms may vary in size but all may be used. Half-fill a tray with moist, gritty compost and insert the corms with their growing points upwards in rows 2.5 cm apart. Fill the tray with more compost, level, firm and label it.
They will grow here to become corms of flowering size. They may be left until they flower two to three years later and just then may be lifted and planted in their permanent positions.