Gladiolus are glorious because they are so beautiful and very, very easy to grow. By following these steps, you may enjoy fresh flowers throughout the summer.
"Glads", as they are sometimes called, are native to Africa, Asia and southern Europe. Though cold hardy from USDA climate zone 7 through 11, they can be grown practically anywhere in the United States. In northern zones, they can be grown as inexpensive summer annuals. In southern zones, they can come back year after year.
They make perfect garden accents. The striking blooms and sword-like foliage make a bold statement in the garden. They're great for cut flower arrangements and for gifts. Just think how good you'll feel carrying an armload of your own home-grown glads to someone you love. Or plant loads of them and invite your friends to pick their own!
Gladiolus prefer full sun, at least six hours per day. Average garden soil with pH between 5.5 and 8.5 is fine. This can be determined by taking a soil sample to your local Cooperative Agricultural Extension Service for testing. Call them first for instructions. They will charge a nominal fee.
The site should be moist but well-drained. Irrigation may be necessary if rainfall is insufficient. Glads should receive one inch of water per week. If they do not receive enough water, the flower spikes will grow crooked. Take care not to over-water.
You may plant them in rows, raised beds, or intersperse them among other plants in your flower garden. Cultivate the soil to a depth of twelve inches and amend it according to soil test recommendations. Remove weeds and debris during cultivation. It is usually a good idea to incorporate superphosphate into the soil before planting at the rate of two pounds per 50 feet of row. If superphosphate is not available, application of 5-10-5 fertilizer at the same rate is recommended.
The corms should not come into contact with synthetic fertilizer. If you use it, you can avoid burning the corms by waiting a week or two before planting them. Or you can place the fertilizer in the bottom of the planting row and cover with an inch or two of topsoil before planting the glads.
Plant four to six inches deep and six inches apart in spring when the weather and soil has warmed. Cover with soil and water well. An application of mulch can suppress weeds and help to retain moisture.
Glads benefit from generous feeding. A second application of 5-10-5 fertilizer may be applied as a side dressing at the rate of two pounds per 50 feet of row when the emerging bloom spike can be felt at the base of the foliage. Again, the fertilizer should not come into contact with the plants. Avoid high nitrogen fertilizers. Too much fertilization can encourage bulb diseases.
Gladiolus differ somewhat by variety and corm size as to how long it takes between planting and blooming. Larger corms bloom sooner. The average time span is between 65 and 95 days. If you plant a mix of varieties, you may enjoy new flowers until mid-summer. Stagger planting them every couple of weeks and you can have an abundance of blooms until late summer.
If cultivation is needed during the growing season to control weeds, take care to cultivate only at the soil surface. Deep cultivation can easily damage the feeder roots.
Various diseases and pests, especially thrips, can afflict gladiolus. It's best to avoid them in the beginning by purchasing commercially produced bulbs. These will have been treated during harvest and processing for sale. Weeding and maintaining a clean garden also helps to prevent problems. If problems do occur, consult with the staff at your local Cooperative Extension Service for recommendations.
Since the flower spikes grow rather tall, they may require staking. The stems are often not strong enough to support the weight of flowers, especially if they are exposed to wind.
You won't be able to resist cutting some for flower arrangements. Choose stems with no more than three flowers in bloom. For best results, cut the stems in the early morning or late evening when temperatures are cooler. Leave a few leaves on each plant so the corms will remain strong. Most growers allow four leaves to remain on the corm. Use a sharp knife or clippers making a clean cut. Plunge the lower ends of the stems immediately in a bucket of cool water.
Allow the leaves remaining on the plants to dry naturally. This will allow them to store plenty of nutrients in the corms for next year's growth. Before frost when the tops have turned brown, trim them back to about four inches.
Many gardeners who live in warmer areas just leave them in the ground over winter and they come back year after year. Though this may be acceptable for some, the practice may encourage those thrips, other insects and diseases that should be avoided. So it is best to dig the corms and store in a cool, dry place at temperature around 40 degrees F. Digging and storage is necessary for growers in colder regions where glads are not hardy.
Begin digging by loosening the soil on both sides of the row. Lift the corms gently. Remove the foliage, leaving very little if any at the tops. Spread the corms in a dry location exposed to full sun for a day, then remove them to an airy location out of the sun to dry further. You may spread them on layers of newspaper. Some gardeners construct tables or trays with mesh bottoms for drying. Such structures can serve to dry other bulbs and corms after harvest. Stir the corms to allow all sides to dry, especially during damp weather. You may even expose them to an electric fan. Dried soil should fall away during the process. Remaining soil should be brushed off before final storage. During cleaning, the corms may be inspected. Those that are damaged or diseased should be discarded.
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