Gladioli bulbs are an easy to grow, summer flowering, plant and they are especially popular in floral arrangements. The Gladioli produces tall spikes of large blossoms from the base and come in a variety of colours including white, several shades of yellow, pink, red and purple. The flowers often have brightly coloured throats. Some bulbs names include Holiday Super, Shocking Butterfly, Satan n’ Lace, Perseus Butterfly, Vera Lynn, Jessup and many more.

HOW TO GROW GLADIOLI BULBS

Although they are classified as bulbs, “Glads” grow from corms (stem with distinct nodes and internodes), which are enclosed in a paper-like covering or tunic. Gladioli bulbs are easy to grow but they are not winter hardy. They must be dug in September and stored until planting time the following May or be replaced annually. Some experts recommend treating them as annuals because they are more likely to get large, healthy, blooms each year that way and you don’t have to fuss with storing them.

Gladioli Bulbs must be planted after the danger of frost is over. Plant some bulbs every two weeks if you want to achieve continuous blooms throughout the summer but stop planting these bulbs in early July. When buying bulbs, select corms 35mm to 55mm (1½ to 2 inches) in diameter as they will produce large and very attractive flower spikes. Smaller corms may not produce flowers. The depth to plant varies with the size of the corms to be planted.

Plant large corms 100mm to 150mm (4inches to 6 inches) deep and space them 150mm (6 inches), apart. Small corms should be planted at a depth of 75mm (3 inches). Gladioli bulbs require well drained soil in a sunny location to perform best. Glads generally bloom within 8 to 10 weeks after planting. They require little special care during the growing season but water the plants weekly during hot or dry weather.

Cut Glads to use for indoor decoration as soon as the bottom flower on the spike has opened. Most of the other blooms will open when the spike is brought indoors and placed in water. When cutting the glads, be sure to leave at least 3 or 4 leaves at the base of the plant. Remove all flower spikes on gladioli remaining in the garden as soon as the flowers are gone. Continue to weed and water the area and, when the leaves begin to turn yellow, the corms can be dug.

SUMMER CARE

Apply a layer of mulch such as straw, grass clippings, or pine needles to help keep the weeds down. Remove any weeds that do come up. Mulch will also help to conserve moisture in the soil and cut down surface evaporation. Adequate watering or rainfall is needed for the best quality blooms so be sure your Gladioli bulbs receive water as required.

CUTTING FOR BOUQUETS

Take a sharp knife, or florist’s shears, and a tall bucket of lukewarm water when cutting Glads for bouquets. Cut the flower spikes in the morning or at night but not during the heat of the day. Cut the spikes that have one, two, or possibly three flowers open.  The rest of the blooms will open, in order, up the spike. Allow at least four leaves to remain on the plant if you wish to re-use the corms.

Cut the stalk diagonally and place it in the lukewarm water immediately. Once you’ve collected all the glads, keep the bucket in a cool, dark place for a few hours so that the blooms “harden off”. Use floral preservative in the water before arranging the glads. As lower flowers fade, remove them. Cut about 25mm (1 inch) of stem off the bottom of each spike every few days.

STORAGE

Dig gladiolus corms up if the foliage has been killed by frost. Shake off excess soil and sort the corms. Cut the stem just above each corm. “Preserve” corms for about three weeks in a warm, dry, airy place. At this point, the corms you planted in spring will easily break off the bottom of the new corms that developed over the summer season. Remove the old, spent corms and save the new ones.

Place the new corms in paper covers, cloth sacks, or nylon pantyhose legs. Store them in a well-ventilated place that’s dry and cool. Ideal storage temperatures range from 1°C to 7°C (35°F to 45°F); the cooler the better but do not allow them to freeze.

When you start digging the corms, you’ll notice a number of miniature corms attached to the main one and they are known as cormels. They should be able to bloom in two or three years if you save them and replant them each spring. Save only the largest ones, at least 15mm (½ inch) in diameter, to play safe. Plant them about 35mm to 50mm (1½ to 2 inches) deep.

PESTS

Gladioli bulbs are susceptible to a number of diseases and are prey to insects as well. To minimize the chance of insect problems, always start with non-infected, sound corms. Eliminate any corm that looks odd or feels soft or crumbly. Practice “crop rotation” if possible and plant glads in different locations from one year to the next. If plants are yellow or stunted, assume the worst – virus infection, for which there is no cure – and completely destroy them.

If leaves appear streaky, flowers fail to open or are discoloured, you may have thrips. Thrips are tiny insects that can infect stored corms. Use a form of fish emulsion, because of the Potassium & Boron content. If always growing any bulbs, use fish emulsion in your compost heap, the Boron content will keep the thrips at bay. The best possible way to control thrips is to  treat the corms as they go into storage. There are several methods you can try including keeping the corms cool enough. At temperatures between 1°C to 4.5°C (35°F and 40°F), thrips cannot survive.