Costa Gladiolus

Upon Arrival:

Plant bulbs as soon as possible, once you have received your shipment. If you cannot plant right away, remove the bulbs from plastic bags and put them on trays with damp peat moss or sawdust in a cool, well-ventilated place until you have a chance to plant them. Do not let the bulbs freeze. Plant outdoors once the conditions are right for your hardiness zone.

Planting:

Plant the corms 6 inches deep, pointed ends up, and 6 inches apart at 2 week intervals. Start planting after the last spring frost and continue until the end of June for a long season of bloom. Deep planting reduces the need for staking. If you are planting Glads for a cutting garden (or stealing a row from your vegetable garden), set the corms at the bottom of a trench 8 inches wide by 8 inches deep, covering them with 2 inches of soil initially, then gradually filling in the trench as the plants grow.

Growing:

Glads do best in full sun in a light, evenly moist soil. A light application of a low nitrogen fertilizer can be used at planting time. Glads need plenty of water during growth but they also must have good drainage. Staking is usually necessary after the plants are 12 inches high, or you can try hilling up soil around the stems to a height of 6 inches.

Note:

When cutting the stems, leave 4 leaves on each stalk. If flowers do not open or are deformed and streaks appear on the leaves, you may have thrips. To control gladiolus thrips spray with a registered pesticide throughout the season or dust bulbs with a bulb dust before storage. After the foliage yellows in early fall, dig the corms, cut off the tops and store them in a dry airy place for 3 weeks. Then separate the largest of the new corms that have formed on top of the old withered ones. Store these in bags made from old nylon stockings (for good air circulation) in a cool dry place over winter.

Overwintering:

Wait until the first frost has killed off the foliage above the ground before digging. After a gladiolus flower spike is done blooming, the plant concentrates its energy into the corm at the base of the stem. Digging up gladiolus can start about eight weeks after this, but you can do it any time until the frost arrives. Knowing when to dig up gladiolus corms might be the trickiest part, but it’s generally safe if you wait until all of the plant matter has turned brown and died back. Once the foliage is brown, you can start gently digging up the gladiolus corms from the soil.

Dig the corms of gladiolus using a garden fork or spade, digging far enough away so that you don’t touch the corm. Pull the plant by its dried leaves and shake it gently to remove any loose dirt. You may see some miniature corms growing on the bottom, which you can grow into full-sized plants in a couple of years. Leave dug corms on top of the soil for two days to allow them to dry. Transfer the corms to a cardboard box and place it in a warm dry place with good air circulation, at about 85 F (29 C). Keep the corms here for about two weeks to allow them to dry completely. Gladiolus forms a new corm on top of last year’s old one, and you’ll be able to separate the two after drying, as well as removing the cormlets. Discard the old corm and place the new corms and cormlets back into cardboard boxes, after removing any excess dirt you may find. At this time, you can also cut the dead foliage off.

When storing gladiolus bulbs, it’s important that you defend against rotting and diseased corms. Inspect them before final storage, throwing away any you find that have soft spots or mushy places. Dust the corms with an anti-fungal powder before putting them away for the winter. When thinking how to store gladiolus over the winter, think about imitating the environment the corms would experience in nature, only just a little bit better. Place them in single layers in cardboard boxes with newspaper in between the layers or store them on screens or in onion bags. You may also place the corms in a breathable bag, like a paper bag, a cloth bag or nylon pantyhose. This will allow the air to continue to circulate around the gladiolus corms while they are being stored. Keep the corms in a cool, dry spot just about freezing, or around 40 degrees F (4 C). Many people choose the vegetable bin in their fridge or an attached garage to store their gladiolus corms. An unheated basement or enclosed porch is ideal as well. Store the corms until next spring, when all chance of frost has passed.