Gladiolus are popular summer flowering bulbs that produce tall spikes of brightly colored, ruffled blooms Their sword-like foliage and vertical form make them ideal cut flowers and striking focal points in flower beds and borders.
However gladiolus have very specific growing requirements. If these needs are not met you may end up asking why are my gladiolus not blooming?
Here are some of the most common reasons for lack of flowers on gladiolus plants and tips to get your glads flowering their best.
Growing Conditions Are Not Ideal
Gladiolus originated in South Africa and require full sun and well-drained soil to thrive. They will not bloom well in shade or soggy soil.
Some things to check regarding gladiolus growing conditions:
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Sunlight: Gladiolus need a minimum of 6 hours of direct sun per day. Morning sun is best to reduce risk of sunscald on the flowers. If your planting area gets less sun, this could be why your glads are not blooming.
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Soil drainage: Gladiolus corms will rot if left in wet soil. Make sure your planting site does not collect water or remain soggy after rain. Improve drainage by amending soil with compost or small gravel.
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Soil nutrition: Gladiolus are heavy feeders that perform best in fertile, organically rich soil. Work in compost or organic fertilizer before planting. Side dress with a balanced fertilizer when foliage appears.
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Air circulation: Avoid cramped planting sites with poor air flow. Good air circulation reduces foliar diseases.
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Wind protection: Tall gladiolus flower spikes are easily damaged by strong winds. Site them in a location sheltered from gusty winds.
Planted Too Deeply
Burying gladiolus corms too deeply is a very common mistake. If covered by more than 4-6 inches of soil, the corms can rot before they sprout.
Corms should be planted with the top 1/3 above soil level. This ensures proper drainage and oxygen circulation to the corms for healthy growth.
Corms Are Too Small
Large, healthy corms that are at least 1.5-2 inches wide have the best chance of blooming the first year.
Smaller cormels may take 2-3 years to reach flowering size. Nurture young corms by keeping them well fed and watered as the foliage develops.
The following year, you should see taller, stronger plants and flowers.
Incorrect Timing
Gladiolus corms need warm soil to sprout and grow. If planted too early in cool spring soil, emergence will be delayed.
Wait until daytime temperatures are consistently 60°F or warmer before planting gladiolus outdoors. Or start corms indoors 6-8 weeks before your last expected frost date.
Conversely, planting too late in the summer won’t allow enough time for plants to grow and flower before first fall frosts.
Aim to have gladiolus planted by early summer so they have at least 90 days of growth before temperatures cool.
Watering Issues
Insufficient water early in the season can prevent gladiolus growth and flowering. But overwatering can be equally problematic.
Here are some key points for proper gladiolus watering:
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Keep soil evenly moist but not saturated after planting until sprouts emerge.
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Water thoroughly when blooming to prolong the flowering period.
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Avoid wetting foliage, as it can lead to diseases. Water at soil level.
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Let soil dry slightly between waterings. Good drainage is very important.
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Reduce watering as foliage starts to yellow in fall.
Light Deprivation
As mentioned, gladiolus require full sun – at least 6 hours of direct sunlight daily. Insufficient light leads to weak, floppy growth and lack of flowers.
If your glads are not blooming, assess your sunlight levels. Morning sun is ideal. Afternoon shade helps prevent sunscald to blossoms.
You may need to thin nearby trees or shrubs to improve sunlight penetration. Or consider moving gladiolus to a new sunnier location.
Failure to Stake
The tall, top-heavy flower spikes of gladiolus easily topple over without proper staking. Staking prevents damage to developing flower buds from snapping stems.
Insert stakes when growth is around 1 foot high. Tie stems loosely to allow room for growth. Stake every 2-3 weeks as plants grow taller.
Use stakes at least 4-5 feet tall for standard gladiolus varieties. Shorter stakes can work for dwarf types under 3 feet.
Nutrient Deficiencies
Lack of key nutrients can lead to spindly, weak gladiolus growth with few or no flowers.
Make sure to give glads a balanced fertilizer when growth begins in spring. Side dress again when the first flower spike appears.
Organic sources like compost, manure, bone meal and kelp meal provide a slow, steady release of nutrition.
Limited phosphorus promotes foliage over flowers, so make sure fertilizer has an even NPK ratio.
Corm Damage or Disease
Damaged, diseased or decaying gladiolus corms often fail to flower properly. Inspect corms carefully before planting. Look for:
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Soft, mushy spots which indicate rot
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Shriveling or withered appearance
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Cracks, holes, or insect damage
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Lesions or scabs from disease
Discard any affected corms to prevent spreading infection. Start fresh with new, healthy corms each year.
Pests
Gladiolus have several insect pests that can hamper flowering:
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Thrips – Tiny sucking insects that cause flower buds to deform and drop. Use insecticidal soap.
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Aphids – Clustered on leaves and stems, sucking plant juices. Strong sprays of water can dislodge them.
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Cutworms – Chew through stems at soil level, causing plant collapse. Use cutworm collars around plants.
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Iris borers – Larvae tunnel and feed inside leaves and corms. Remove and destroy infested foliage.
Diseases
Fungal and bacterial diseases can also affect gladiolus flowering:
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Botrytis blight – Gray fuzzy fungal growth on leaves and flowers. Improve air circulation.
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Fusarium – Corm rot caused by fungal infection. Avoid planting in same spot annually.
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Curly top virus – Leaves twist and curl, plants are stunted. Control leafhopper insect vectors.
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Rust – Powdery rust-colored spores on leaves. Cut and remove affected foliage promptly.
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Scab – Rough corky lesions on corms. Soak corms in fungicide before storage.
By identifying and addressing the potential reasons your glads are not blooming, you can get them performing their best. With proper care, you’ll be rewarded with their signature spires of vibrant color in your garden.
Frequently Asked Questions About Non-Blooming Gladiolus
Here are answers to some common questions about lack of flowers on gladiolus plants:
Why are my gladiolus not blooming even though the foliage is nice?
This often indicates insufficient sunlight. Gladiolus produce abundant leaves in shade or part sun but need a minimum of 6 hours of direct sun daily to flower well. Increase sunlight levels if possible or replant in a sunnier spot.
I planted gladiolus bulbs last year and this year there are no flowers. Why?
Newly planted small gladiolus corms may not bloom the first season. It can take 2-3 years for them to reach maturity and flower. Make sure to water and feed the plants as foliage grows to help corms expand faster.
My glads were not blooming so I added more nitrogen fertilizer. Now I have lots of leaves but still no flowers. Why?
Too much nitrogen fertilizer causes excess leaf growth at the expense of flowers on gladiolus. Use a balanced fertilizer with an even ratio of nitrogen, phosphorus and potassium (the NPK numbers on the label). Phosphorus deficiency particularly inhibits blooming.
What should I do if my glads start blooming but then the buds turn brown and die before opening?
Thrips are the likely culprit. These tiny sucking insects attack flower buds causing them to deform and abort before fully opening. Use insecticidal soap or neem oil and be persistent, as thrips are difficult to control. Remove affected buds promptly to limit spread.
Why do the bottom leaves on my glads keep turning yellow and drying up?
This is natural as the plants finish flowering. The lower leaves senesce first while upper foliage remains green until all flowers finish. Remove spent leaves and stems once
