Gladiolus

( glad - ee - OH - lus )

At-A-Glance Information

These popular ornamental flowering plants, nicknamed Glads, need full sun and regular waterings during their growth and blooming periods to perform well. Their flowers will attract myriad pollinators to your garden, including hummingbirds, bees and butterflies. Glads are prized for their colorful blooms which form on tall spikes, the buds at the base of the spike opening first. Gladiolus plants are commonly grown as members of cut flower gardens and also do well when planted in border beds behind lower, mounding plants. They can also be grown in pots with annuals around their base. Take care when planting these beauties in your garden, as plant parts are toxic to humans and pets if ingested (especially the underground corms).

Gladiolus Species and Varietals

The genus Gladiolus is a member of the plant family Iridaceae and includes around 300 species. Gladiolus is Latin for 'small sword' which is a reference to the plant's leaf shape. These flowers grow best in zones 4-9 and 12-24, though this can vary somewhat depending on the species. For more information, see the descriptions below. To find your zone, click here: Zone Map.

Gladiolus alatus (Painted Ladies, King Kalkoentjie, Kipkippie, Little Turkey)
These flowers are called 'Little Turkey' in their native range in South Africa, referring to the flower's shape, which looks like a turkey's wattle. Blooms are reddish-orange and showy, reaching 10 inches tall atop flowering stalks.

Baby Gladiolus
These plants grow well in zones 4-9, 12-24 and H1, though can be grown in zones 2b and 3 if they are a particularly hardy cultivar. This is a group of hybrids that have flaring blossoms up to three inches across in short, loose spikes. They will flower in late spring in white, pink, red and lilac, sometimes marked with contrasting colors. They can form large clumps if allowed to stay in the ground season after season.

Gladiolus communis (Eastern Gladiolus, Common Corn-Flag)
This species is native to Southern Europe and has maroon flowers that bloom in spring and summertime on spikes that are up to three feet tall. Plants reach a little over three feet tall, and are widely naturalized in frost-free locations around the world. 

Gladiolus flanaganii (Suicide Lily)
This species can be found growing on steep cliffsides in Natal, South Africa. Plants produce red flowers that bloom in summer in their native range, and go dormant shortly afterwards. The species is named for botanist Henry George Flanagan. 

​Gladiolus grandiflora Hybrids (Garden Gladiolus)
This group is very popular and widely-known, with flower spikes reaching 3-6 feet tall that bloom in late spring and summer. Flowers are up to 8 inches across and come in a wide range of colors. This group also includes 'Mini Glads' which grow up to 3-4 feet tall and hold up to 18 flowers per spike.

Gladiolus italicus (Italian Gladiolus, Field Gladiolus, Common Sword-Lily)
These perennial flowers are native to Eurasia and North Africa, and is a common weed in many areas around the globe. Flowers are held towards the top of spikes and are bright pink. 

​Gladiolus murielae (Gladiolus callianthus, Acidanthera bicolor) (Abyssinian Sword Lily, Fragrant Gladiolus)
This species is native to Africa and blooms in late summer to fall with flowers of creamy white marked with brown. Blooms are held on spikes up to 2-3 feet tall. These beautiful flowers are widely cultivated in many areas, commonly pulled from the ground each year in places where freezing winter temperatures occur.

Gladiolus orchidiflorus (Orchid Kalkoentjie, Orchid-Flowered Sword Lily)
These flowers grow well in clay and sandstone soils, and commonly grow in grasslands. They are native to South Africa. Individual plants reach about 2 feet tall.

Gladiolus palustris (Marsh Gladiolus, Sword Lily)
This species reaches between one and two feet tall and produces magenta to bright pink flowers. Leaves are green. This species is native to central and northwestern Europe. 

​Gladiolus primulinus and Butterfly Hybrids
This species blooms in summertime, with hood-shaped flowers in a wide variety of colors. They grow about 3-4 feet tall. The group of Butterfly Gladiolus in this species has flowers with marked throats that mimic markings on butterflies.

Gladiolus triphyllus (Three-Leaved Gladiolus)
This species is endemic to Cyprus, and produces a plant that reaches between 6 and 12 inches tall at maturity. Flowers are dark pink and white, and have a fragrance that is strongest in the late afternoon. Flowers bloom from March through May.

Gladiolus tristis (Ever-Flowering Gladiolus, Marsh Afrikaner)
This species is native to South Africa, and has naturalized in places like Australia and California. They typically reach between 1.5 and 3 feet tall and produce three leaves. Flowers are creamy yellow to white, and are fragrant.

Caring for Gladiolus

Gladiolus plants can be sown from seed, or corms can be purchased online or at reputable nurseries. Specimen plants can also be purchased at many garden centers. They are best in full sun, though they can also get by in areas with partial shade. They will flower and grow best in a spot that receives between 6 and 8 hours of sun each day. They prefer well-draining soil that is moderately fertile with a pH of between 6.0 and 6.5. If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Mulch the planting area with organic mulch to increase soil moisture retention, suppress weed growth, and maintain constant soil temperatures. Water newly planted Gladioli regularly to help them develop a strong root system. At maturity during their active growth and flowering periods in spring and summertime, they appreciate weekly irrigations.

Fertilize yearly in early springtime with a application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing and flowering seasons. Deadhead flower spikes to neaten the appearance of plants, unless you will be gathering seeds for propagation. At the end of the growing season after foliage has yellowed and died back, it can be removed. Corms will need to be divided every few years, as they will form clumps over time and possibly outgrow their space, especially if they are cultivated in a container. For instructions on how to divide Gladiolus flowers, see the Propagation section below.

Propagation

Gladiolus flowers can be propagated either by division or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the division method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Glads, follow the instructions below:

Propagating Gladiolus by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
  2. Harvest your seeds. The seed heads on plants are pretty easy to spot, they're left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
  3. In either late winter or early springtime, get your container prepared. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 4-6 weeks from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  4. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 65 and 72 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Propagating Gladiolus by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil (any kind will do, though it does need to be well-draining), compost and pots (12 inch pots will do, and these are only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in very early spring (after the plant has entered dormancy, but before it has begun its new spring growth), and needs to be done every few years regardless of whether you have the goal of propagating the plants for best performance, especially if you are growing Glads in containers. To propagate by division, follow these steps:
  1. Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the root(s). Once you have worked it up out of the ground, lay it out.
  2. Start to tease apart the roots with your gloved fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick corm section attached.
  3. Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. Then, plant your corms and water thoroughly.
  4. Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home. Then, enjoy watching it sprout in the next growing season.
Gladiolus seed pods are left behind after flowers have faded, and will open up and release seeds when mature.
Gladiolus seeds are flattened, papery, and typically tan to light brown in color.

Problems and Pests

Gladiolus plants can have issues with the following pests and diseases in the landscape:
  • Bulb Mites
  • Caterpillars
  • Thrips
  • Mealybugs
  • Nematodes
  • Slugs and Snails
  • Aphids
  • Spider Mites
  • Root Rot
  • Fusarium Yellows
  • Leaf Spot
  • Grassy Top
For more information on these pests and diseases, including how to treat and manage them, consult the following pages:
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Gallery

Here, purple and pink Gladiolus plants grace an entryway with color.
Gladiolus plants will typically need some staking to remain upright under the weight of their large flower spikes.
Gladiolus are classic cottage garden plants.
Gladiolus flowers bloom from late spring through early fall.
In cooler regions, the corms will need to be dug up and stored over the winter months.
Gladiolus can be grown in large containers, which can be moved indoors if necessary during cool weather.
Glads are pollinated by bees.
Gladiolus flower spikes are common members of cut flower arrangements.
Here, an informal bed is graced with Coneflower, Gladiolus, Bee Balm, Salvia, and Galium.

Videos

How to plant Gladiolus bulbs in containers.
How to dig up, break up, and store Gladiolus corms.
Get your burning questions about Gladioli answered.
A care guide for Gladiolus plants.

Resources

How to Grow Gladioli: The Complete Gladiolus Flower Guide
How to Grow Gladioli
How to Grow and Care for Gladiolus
Learn How to Plant, Care, and Grow Impressive Gladiolus Flowers
Wikipedia: Gladiolus
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 339 - 340, Gladiolus
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