Gladioli, perennial corms flowering plants, are part of the iris family, commonly referred to as 'sword lilies' due to their distinctive pointed leaves.
They're vibrant and versatile, brightening up borders or in more organised rows for producing cut flowers. Gladioli also work well as plants for containers, creating striking and colourful displays in pots and planters.
Gladioli are primarily summer-flowering plants, appearing from June through to September, typically flowering around 90 days after they're planted.
Gladioli are considered relatively easy to grow, particularly during the first summer, making them a great flower for beginners.
Their vibrant, high-pigment jewel tones will also make a striking addition to small gardens or plainer outside spaces and patios, as well as weaving in interest to bigger gardens and borders.
Here's how to grow gladioli, from choosing the right variety to expert tips on planting, maintaining and deadheading this beautiful flower.
1. Choosing Gladioli
Before you begin, you'll need to choose the type of gladioli. Hardier varieties can be planted in the ground, but be wary that they'll only survive in warmer gardens. In cooler conditions, they're unlikely to flower.
As an alternative, gladioli can be grown in a container and moved around seasonally - they will need to be undercover during winter and have summer outside, basking under the sun. Specialist species like Gladiolus cardinalis and Gladiolus carneus work well in containers.
Meanwhile, hardy gladioli such as Gladiolus communis subsp. Byzantinus, a perennial with erect sword-shaped leaves, can be left in the ground to grow year after year.
2. Where and when to plant gladioli
Gladioli like to grow in well-drained soil in a sunny, open space without too much competition from surrounding plants, so choosing the right spot is essential. This vibrant plant thrives in rich, well-drained soil.
"Test the soil in planned areas for drainage," Matthew Wilson, professional gardener and CEO of Handy Gardeners, tells us.
"In spring, ensure the soil is warm and exposed to sunlight," Matthew suggests. It's best to plant gladioli in the spring (from April to mid-May) after the last frost.
3. How to plant gladioli
As a rule of thumb, space corms out at a similar distance to their depth, the RHS advises.
Place corms with the pointed end up, roughly the same distance deep and apart (around 10-15 cm). Plant corms a little deeper for tall gladioli, if you want to improve their stability in the wind.
"Stagger planting for blooms that will last," adds Matthew. If you're planting gladioli in a container, use a large pot that's at least 12 inches deep, with plenty of drainage holes.
4. Encouraging better growth
"Make sure to keep the area clean from weeds and provide the appropriate support to the flower," Matthew suggests.
"Stem support comes from applying a balanced fertiliser. Otherwise, blooms can become weak and stemming is dry," the expert gardener continues.
Non-hardy gladioli varieties can be lifted in the autumn and stored in warm, dry conditions to ensure they last the winter. It's important to dry the corms for around two weeks before removing the soil and storing them.
5. Deadheading gladioli
Gladioli should be deadheaded throughout mid and late summer when flowers begin to fade to ensure optimal health.
"Make sure to effortlessly remove flowers that have bloomed and keep the area looking clean," Matthew suggests. It's important to leave the green leaves in tact so that they can continue to feed the corms for next year.
After flowering in the late summer and autumn, once the flowers have died, leave the foliage to die back naturally for around four to six weeks to protect next year's flowers.
"You should stop any flowers from wilting after they have bloomed, and allow the foliage to die off to replenish the corms for the following year," Matthew explains.
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