Gladioli are old-fashioned flowers with tall stems and large, colorful blossoms. Gladioli are also popular cutting flowers. Gardeners living in USDA zones 6 and lower must remove gladiolus bulbs from the soil prior to the first autumn frost. Gardeners living in USDA zones 7 and 8 may leave the bulbs in the soil after mulching them to protect them from winter temperatures.
Choose a planting area that receives full sunlight and protection from high winds. Prepare the planting area by working the soil with the garden spade down to a depth of at least 12 inches. Add between 2 and 4 inches of compost to the top of the soil and work this in with the garden spade.
Dig holes for the gladiolus bulbs that are 4 inches deep and approximately 6 inches apart. Place one bulb into each prepared hole so that the pointed side of the bulb faces up. Cover the bulbs with soil and pat the soil down firmly over the bulb. Water the newly planted bulbs generously.
Insert a bamboo stake at each place where you planted a bulb if the gladiolus variety is taller than 3 feet high. Do not damage the gladiolus bulbs as you insert the stakes.
Place between 2 and 4 inches of mulch around the gladiolus bulbs to keep the soil moist and prevent weeds. Provide the gladiolus plants with water if less than 1 inch of rain falls during a one-week period.
Clip off blooms as they wither. Cut off the plant stalks when all of the flowers are finished blooming. Do not remove the foliage until it yellows at the end of the growing season.
Add another 1 to 2 inches of compost over the growing area prior to winter if you live in USDA zones 7 and 8. Dig up the bulbs before the first frost if you live in USDA zones 6 and under. Cut off all foliage from the bulbs and dry them for one to two weeks in a warm, well-ventilated area. Sort through the bulbs and discard any bulbs that appear old and worn-out. Place newer bulbs in a large, mesh bag and store in a well-ventilated area with temperatures between 35 and 45 degrees F.
If you stored the gladiolus bulbs during the winter, replant them the next spring following steps two through four.