How to Plant and Grow Gladioli
Gladioli are members of the Iris family and have long, sword-like leaves that are surely how they got their name, gladiolus, from the Latin gladius, meaning sword. Sometimes called sword lilies or sword flowers, these perennial flowering plants have enjoyed centuries of popularity in folk medicine, flowerbeds and bouquets.
Symbolizing remembrance, strength, honor and integrity, gladiolus is the birth flower for the month of August and the flower associated with 40th wedding anniversaries. But even for those born at other times of the year, these beautiful blooms are a welcome addition to cutting gardens and butterfly gardens and are often used to add color and height in landscaping design.
Gladioli grow to heights of between about two and five feet and come in single and bi-colored blooms in a wide variety of colors, including white, cream, yellow, green, orange, apricot, pink, red, and purple.
Planting Gladiolus Bulbs
Gladiolus is often planted in the back of flowerbeds and borders as a tall, colorful addition among other flowers and plants or against fences and structures to provide support for taller varieties. They prefer full sun and well-draining soil and do not compete well with weeds. They can be grown in the ground, raised garden beds or containers.
Choose a spot in your garden that gets at least six hours of sun each day. If you have the heavy, clay soil that is found throughout much of Southern California, you may want to plant your gladioli in containers or raised beds.
The bulbs will rot in heavy, wet soil, so it is imperative that the soil is well draining. To make your clay soil more habitable for glads, work compost into the top 10 to 12 inches to improve the soil structure and enhance drainage.
Once you have prepared the soil, plant smaller corms (bulbs) about three to four inches deep and larger corms about five to six inches deep. Whether you are planting in rows or interspersing your gladioli with other flowering plants, be sure to give each corm about eight inches of space on all sides.
How to Care for Gladiolus
Gladioli are easy-to-grow bulbs that require little care once established. In zones 8 and above, you can overwinter your corms in the ground, making these a low-maintenance perennial that will continue to provide your garden with beautiful blooms year after year. In zones 7 and below, you will need to dig up the corms each year before winter and replant them near the last frost in spring.
Glads are most often planted in spring and once you have the bulbs in the ground, there is little more to do. You will need to keep the soil moist but not soggy as the roots and first shoots develop. You can then move to one inch of water per week but will likely need to double that when it is particularly hot and dry. Adding a thick layer of mulch around the plants will help the soil retain moisture while also providing some support for the base of the plant.
You will need to keep your flowerbeds completely free of weeds, since gladioli do not compete well. If you choose to fertilize throughout the growing season, you will want to add your first dose of water-soluble fertilizer once your glads are about 10 inches tall, and then again when you first begin to see color on your flower spikes.
Some of the shorter varieties of gladiolus will do fine without staking, but most varieties require staking to support the long, narrow flower spikes. Inexpensive, circular supports are usually all you need for this.
Flower spikes and leaves can be cut for floral arrangements, but be sure to leave enough of the leaves to allow the plant to continue to thrive.
If left on the plant to add color to your garden, deadhead blooms as they fade, but do not remove the foliage until the end of the blooming season when the foliage yellows. You can then remove the foliage and add a layer of mulch to overwinter the corms in the ground.
If you live in zone 7 or below, dig up the bulbs, brush off debris, cut the stock to about ½-inch to one inch from the top of the corm, dry the corms in the sun for a few days, and then place them in a bucket with peat moss to store in a cool, dry spot until spring.
Gladiolus grown from healthy corms usually have few issues with pests or diseases. The most common issue with gladioli are thrips, which are insects that eat the foliage. If you begin to see potential insect damage, spray each plant with a neem oil-based insecticide to eradicate the infestation.