Gladiolus, also known as Sword Lily, is a stunning perennial flower that blooms in the summer. The name is actually derived from the Latin word for sword, ‘gladius’. The many varieties of Gladioli come in all sorts of colors, bright and soft. You’ll find them with single color, bi-color, and even tri-color petals. They look amazing planted in groups, and will definitely impress in any garden.
Gladiolus, with their tall spikes of vibrant, ruffled blooms, are a stunning addition to any summer garden. Also known as sword lilies, gladioli come in a wide range of colors like red, pink, orange, yellow, white, purple and more. Planning when to plant these bulbs is key to getting the most out of their spectacular floral show.
An Overview on Gladiolus
Before diving into gladiolus planting times, let’s go over some background on these flowers. Gladiolus are herbaceous perennials, grown as annuals in cold climates. Their Latin name comes from the word “gladius” meaning sword, referring to the sword-like shaped leaves. The flowers bloom on tall, straight stalks arising from a bulb-like structure called a corm. Each stem can produce around 5-20 blooms.
Gladiolus originated in tropical and subtropical Africa, Europe, Asia and the Mediterranean. Today, they are popular flowers worldwide. With over 260 species, there is a huge variety of flower forms, colors and heights. Gladioli grow best in fertile, well-drained soil and full sun. They thrive with regular water. In ideal conditions, gladiolus can reach heights of 2-6 feet.
When to Plant Gladiolus Bulbs
Timing is important for gladiolus success. Here is an overview of when to plant gladiolus corms for the best results:
Spring Planting
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Plant gladiolus corms in early to mid spring, around 2-4 weeks before the last expected frost date for your region. This gives time for the plants to establish before summer heat kicks in.
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Stagger planting every 2-3 weeks until early summer for a continuous display of flowers throughout the season.
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Early, mid and late season gladiolus varieties extend the bloom period when planted at different times.
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In warm climates, gladiolus can be planted in fall through early winter.
Summer Planting
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Continue planting gladiolus in early summer for flowers in late summer and fall
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Stop planting new corms by mid to late summer so plants have time to bloom and foliage to die back before first frost
Region-Specific Spring Planting Dates
Here are some general planting date ranges for a spring crop in different zones:
- Zone 3-4: April to early May
- Zone 5-6: Mid April to mid May
- Zone 7-8: March to April
- Zone 9-10: February to March
Check your local frost dates and adjust planting times accordingly. Earlier in the range is ideal for fastest sprouting.
Planting in Stages for Continuous Blooms
Gladiolus flowers don’t all bloom at the same time. Each plant flowers for about 2-3 weeks.
To ensure a steady flower display, it’s best to plant gladiolus corms in succession, every 2-4 weeks until early summer.
Staggering gives a sequence of plants at different stages of growth. As one group finishes blooming, the next wave starts to flower.
Aim to make 2-5 successive plantings in zones 3-8 for blooms over a 2-3 month period. In warmer zones 9-10, go for 5 or more successive plantings for the longest flowering window.
When staggering, use early, mid and late season gladiolus varieties. This expands the bloom sequence further.
Growing Gladiolus as Annuals vs. Perennials
Gladioli can be grown as annuals or perennials depending on your climate:
As Annuals
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In cold climates (zones 3-6), treat gladiolus as annuals.
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Plant new corms each spring for flowers in that season.
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At the end of the season, dig up corms and store over winter before replanting next year.
As Perennials
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In warm climates (zones 7-10), gladiolus can grow year after year.
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Leave the corms in the ground over winter. Mulch for insulation in colder zones.
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Corms sprout again in spring to flower in summer. Divide crowded clumps every few years.
Tips for Successfully Planting Gladiolus Bulbs
Follow these tips when planting gladiolus corms:
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Prepare soil well by mixing in compost. Gladioli thrive in fertile, well-draining soil.
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Plant the corms 4-6 inches deep and 6 inches apart. Plant upright with the flat side down.
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Water after planting and regularly throughout growth. Give at least 1 inch of water per week.
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Apply mulch around plants to conserve moisture and reduce weeds.
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Stake tall varieties if needed for support against winds and heavy blooms.
When to Dig Up and Store Gladiolus Corms
If overwintering gladiolus as annuals, you’ll need to dig up and store the corms:
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Allow the foliage to die back completely after flowering ends, usually around fall frost.
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Once it turns yellow or brown, cut off the dead tops and carefully dig up the corms.
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Remove any small cormels that have developed and set aside to plant next year.
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Dry and cure the corms for 2-3 weeks in a warm spot with good airflow.
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Store in a cool (40-50°F), dark and dry place over winter. Pack in paper or mesh bags.
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In spring, take out the largest, healthiest corms and plant them in the garden again.
Following the guidelines above on when to plant gladiolus ensures you have a gorgeous display of colorful gladiolus blooms in your garden for as long as possible. With proper timing and care, these striking flowers will provide sensory delight throughout the season!
QUICK GUIDE
- WHENPlant in spring Bloom in Summer
- WHERE: Hardiness zone 8–11; suitable zones: 3–11; full sun; well-drained soil
- WATERWater regularly if there’s no rain
- WIDTH & DEPTH3-4” apart 6” deep
Arrival: If you can’t plant your DutchGrown Gladioli right away, it’s important to store them correctly. Take them out of the box right away and put them somewhere dry with lots of air flow where the temperature is between 40 and 65 degrees Fahrenheit.
Garden If you want a lot, you can plant them at different times so that they bloom all summer long. To thrive, they need to be planted in a spot with full sun, in rich and well-draining soil. A layer of mulch will help keep the soil moist. Plant the bulbs approximately 3 to 4 inches apart, and 6 inches deep. Plant them straight up, pointy side up, and flat, rounded side down to give them the best chance of blooming. Make sure they get the equivalent of one inch of rain per week by watering them well, especially when it doesn’t rain. Gladioli can grow to heights between 48 and 60 inches tall. Expect to see your flowers bloom in about 90 days from when the foliage begins to emerge overground. The tall stems are fairly strong, with sword shaped leaves. Up to 20 florets can bloom on each flower spike, which is shaped like a funnel and has open petals with ruffles. These flowers open one at a time, beginning at the base and working their way up to the top of the stem. This means that each flower will give you two weeks of full-color blooms. As they are such large flowers, they can sometimes become a bit top heavy. To keep them from leaning, you can support them with bamboo canes and tie them gently to the canes to keep them in place. You can do the same with a larger area by using more bamboo canes and encircling the section. You could also cut them and use them as cut flowers. To do this, you would cut the flower before it fully blooms, when the top florets are still closed. This way, you are avoiding the leaning and heaviness altogether. Don’t forget to cut off the top bud too. This will keep the other buds from opening as quickly and give you a longer bloom. After they have finished flowering, remove the spent stalks and let the plant wither naturally. In hardy zones, you can leave the bulbs in the ground to perennialize. At the ground level, cut the plant down when it turns brown. It should grow back the next year. In non hardy zones, it’s probably best to treat Gladioli as annual plants. Every year, plant new bulbs, or you can dig up the old ones and store them until the next planting season.
How to plant Gladiolus in your garden:
- In a spot that gets full sun, start with loose, rich soil and a sprinkle of compost.
- Plant the Gladiolus bulbs with the pointy end up and about 6 inches deep. Space them 3 to 5 inches apart.
- Water your plants often, giving them the same amount of rain as an inch a week when it’s dry.
- After the Gladioli have bloomed don’t cut off the foliage. Leave it until it’s completely withered and yellow, then remove.
How to Plant Gladiolus Bulbs
FAQ
What month do you plant gladiolus bulbs?
Should I soak gladiolus bulbs before planting?
How many gladiolus bulbs should I plant together?
Do gladiolus come back every year?
Can Gladiolus grow in shade?
Use them in borders in front of shorter plants or grow them in a grid or rows in a cutting garden. Gladiolus plants need well-draining, slightly acidic to neutral soil in a sunny to a partially shaded spot. Gladiolus plants thrive in full sun but will grow in part shade, although their colors won’t be as bright.
When should I plant Gladiolus corms?
Mix compost (humus) into your soil to improve consistency and fertility. Start planting gladiolus corms in the spring once the danger of frost has passed and the soil has warmed to at least 55°F (13°C). See your local frost dates here. From your last frost date to early summer, plant another round of corms every ten days or so.
How often should you plant Gladiolus?
Plant a group every two weeks in spring. Stop planting in mid-June to give the plants plenty of time to mature before a damaging freeze in fall. When planting long rows of corms to use as cut flowers, plan to stake each stem along one side of the row, tying the stems to the plants they grow. Gladiolus thrive in full sun.
How do you grow Gladiolus?
Gladiolus is an excellent container plant. Fill a large deep pot that has drainage holes with well-draining potting soil amended with compost, spacing the corms about 2-3 inches deep and 4 inches apart. Move it to any part of the garden that needs a pop of color. Prepare other pots a month apart for continuous color all summer and into fall.