Growing Information

The GLADIOLUS is an easy to grow flower that produces tall spikes in a rainbow of colours and bicolours in a range of sizes and forms. Large glads make an elegant statement in vases while miniatures being generally smaller in stature are great for arranging. Glads can provide colour in annual beds and borders. Plant them in groups of seven or more corms of the same colour for best effect. If you are primarily growing for cut flowers you may want to plant them in rows as it will be easier to tend to plants and harvest the flower stalks.

How to Grow Gladiolus

Given a few simple requirements, glads are easy to grow. They do well in a wide range of soil types, provided drainage is good, but they grow best in soil with a pH of 6.7 to 7. Most garden soil that will produce a good crop of vegetables or weeds will also grow good glads with little or no added fertilizer. Glads prefer full sunlight but will do reasonably well with a little high shade early morning or late afternoon. Good air circulation is desirable, so stay away from buildings or other obstructions, which might impede airflow.

Plow, rototill or spade your soil as you would for any other garden plants, it is best to move your glad planting from one area to another each year to help prevent disease carryover in the soil. If soil test or other reliable indicators points to lack of nutrients, a balanced commercial fertilizer such as 5-10-10 may be incorporated into the soil immediately prior to planting, at a rate of 2-3 pounds per 100 square feet. Avoid over fertilizing. Composted animal manure or leaves should be worked into the soil in the fall.

Once you receive your corms, they should be unpacked and be allowed to air in a cool location, such as your basement, until planting time.
Your first planting should be when you would normally plant sweet corn in your area. Corms planted in cold soils are apt to rot before they begin to grow. Subsequent plantings at two-week intervals will ensure bloom over a long period of time. Large corms bloom earlier than smaller sizes and there are Early and Late blooming cultivars as well. (Canadian prairies with shorter seasons are recommended to grow Early to Midseason cultivars and larger size corms)
Plant corms three to five inches deep (about 4 times as deep as their diameter) and from four to six inches apart. Insecticide spread in the trench before covering will discourage underground insects. Before glads bloom, hilling soil six inches up around the stalk helps prevent the glads from tipping during storms. Remember that glads need plenty of water but will not tolerate wet feet. If drainage is a problem in your soil, rows should be raised to facilitate the process.

Weed by shallow cultivation and hand weeding. Avoid packing or heavy caking of soil surface, which prevents soil aeration. If available, a light mulch of straw, grass clippings etc., between rows will discourage weeds and help conserve moisture.
Insect control is important in growing glads. Pests include thrip, which is far the most damaging. Thrip are tiny insects, tan to black in colour and less than 1/8" length, can be controlled by several good combination sprays and dusts, including organic products that are available at your Garden Center. If you chose organic products more frequent applications will be needed. If your patch is not too large and a thrip problem arises, you can use a house and garden spray such as Raid which such be applied within every two weeks to disrupt the thrips life reproduction cycle.

If you live where the ground freezes you will need to dig your corms each year or if you choose not to dig, purchase new corms, and treat them as an annual just as you would with impatiens and other annuals. Glad corms should be lifted in fall before onset of ground freezing weather. About 6-8 weeks after blooming, the corms may be harvested by loosening the soil with a spade or digging fork so the plants can be pulled by hand. The plant should be separated from the corm as close to the corm as possible, either by hand breaking or with pruning shears. You should remove the old tops from the garden to prevent carry over disease. The corms should be cleaned or rinsed off with running water (can dip in Lysol-see under Corm Storage )and then spread out to dry in shallow layers in trays or porous bags in an airy location that will not freeze for a period of 2-3 weeks. During this time a cork layer forms between the new corm and the old mother corm and roots. Break off and discard this corm as soon as possible. If you live where the ground does not freeze in the winter you may choose not to dig your corms; however, disease and crowding may reduce the amount and quality of your bloom. You should remove plant tops 6-8 weeks after bloom from your garden to prevent the spread of disease.

After cleaning, corms should be lightly dusted with a combination fungicide/insecticide dust if available or dip them in a Lysol solution right after harvest ( 4 teaspoons of Lysol per gallon of water for six hours before drying in fall). Place in shallow trays, mesh bags or open paper bags to be stored for the winter. Do not us any covering material. A well-ventilated root cellar is ideal but any room with good air circulation in the average home basement will suffice, if temperatures can be kept between 38-58 degrees Fahrenheit (3-14 degrees Celsius). The lower temperature is the best.

Bring a sharp knife or florist's shears to the garden. Cut the flower spikes first thing in the morning or at night, not during the heat of the day. Cut spikes with one to three flowers open, the rest 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 diagonally through the stalk and place it in a tall bucket with lukewarm water. Once you've collected all the glads you want to cut, put the bucket in a cool, dark place for a few hours so the blooms "harden off". Arrange your flowers in a vase or as desired. You may use a flower preservative in the water if you wish but it is not necessary. More importantly, you should freshen the water and recut the stems every few days. As lower flowers fade, pick them off. This will keep your bouquet looking fresh. Once most of the blooms have faded you may want to cut the spike down to size and arrange in a shorter vase.

These are a delightful way to enjoy the many outstanding cultivars on the market. The shows of Members Societies of the NAGC (North American Gladiolus Society) are listed in the summer issue of Glad World. You can go on the NAGC website for more glad information. Other opportunities such as Fairs and Floral exhibitions exist where you can view glads or display the results of your growing efforts.