Gladiolus (Gladiolus hortensis L.), the queen of bulbous flowers, is a popular ornamental plant from the Iridaceae family. Cultivated for its striking flowers, Gladiolus has become a staple in both domestic and international cut flower markets since its introduction in the late sixteenth century. Most of the 300 wild species originate from Africa, particularly South Africa, with a few from the Mediterranean and Europe. The genus name, given by Tournefort, comes from the Latin word ‘gladius,’ meaning ‘sword,’ reflecting the plant’s sword-shaped leaves.

Why grow Gladiolus?

Gladiolus, a slender herbaceous perennial, is prized for its impressive, long-lasting flower spikes in various shapes, sizes, and vibrant colours, ranging from pink and purple to white, orange, and red. It grows easily from corms, making it perfect for gardens and exhibitions. The flowers are popular in floral arrangements, bouquets, and indoor decorations. In India, Gladiolus is increasingly sought after for its cut flowers due to its long vase life and economic value.

Classification of Gladiolus

Horticultural Classification

 

Gladioli are classified into five types based on flower size and shape:

 

• Large-Flowered (Grandavensis) Hybrids: Ideal for garden displays, these gladioli have triangular, overlapping florets on tall spikes (120-150 cm) that bloom later in the season.

 

• Primulinus: Featuring slender spikes with zig-zag arranged, smaller, hooded flowers, these gladioli grow up to 100 cm and bloom mid-season.

 

• Miniatures (Pixiola): Compact gladioli with frilled or ruffled florets (5-7.5 cm) suited for pots or early cutting. Includes butterfly hybrids with distinctive throat markings.

 

• Peacock Hybrids: Dwarf, multi-coloured gladioli with reflexed petals, perfect for cutting.

 

• Star-Flowered: These types have flat, star-shaped flowers and were developed by Unwins of Cambridge, England.

Commercial Classification

For commercial purposes, gladioli are classified based on spike length and the number of florets:

 

• Fancy: Spike length >107 cm, minimum 16 florets.
• Special: Spike length >96 cm to ≤107 cm, minimum 15 florets.
• Standard: Spike length >81 cm to ≤96 cm, minimum 12 florets.
• Utility: Spike length ≤81 cm, minimum 10 florets.

 

Classification Based on Floret Size

Gladioli are also classified according to the size of their florets:

 

• Miniature: Floret size <6.4 cm.
• Small: Floret size ≥6.4 cm to <8.9 cm.
• Decorative: Floret size ≥8.9 cm to <11.4 cm.
• Standard or Large: Floret size ≥11.4 cm to <14.0 cm.
• Giant: Floret size >14.0 cm.

Classification Based on Color

Gladioli are classified into various colour categories: white, yellow, orange, salmon, pink, red rose, lavender, violet, smokes, tan, and brown. Each colour category also includes shades such as pale, light, medium, and deep.

Growing Requirements: Soil and Climate

Gladiolus grows best in sunny, well-drained locations away from trees, shrubs, and low-lying areas. Ideal soil is fertile loamy to sandy loam with a pH of 6.5-7. Avoid highly acidic, alkaline, or clay soils. If needed, amend clay soils with sand and organic matter to improve drainage. Waterlogged or heavy soils can cause corm rot and stunt growth. In sandy soils, add manure to retain moisture and nutrients. Gladiolus flourishes in moderate humidity and a temperature range of 27°C to 30°C.

Arka Amar variety of Gladiolus

Varieties of Gladiolus

Here are brief descriptions of the gladiolus varieties:

 

1. Arka Amar: Pink florets with white blotch; high yielding, vase life of 8.5 days.
2. Arka Gold: Yellow florets with red blotch; blooms in 74 days.
3. Arka Naveen: Purple florets with pale yellow blotch; vase life of 9 days.
4. Archana: Pink petals with white streak; 16-18 florets per spike.
5. Aarti: Light orange florets with red/yellow blotch; 12-13 florets per spike.
6. Apsara: Purple florets with yellow flecks; early flowering, vase life of 8 days.
7. Aldebaran: Straw yellow florets with red blotch; 12-14 florets per spike.
8. Basant Bhar: Empire yellow florets with magenta specks; 14 florets per spike.
9. Friendship: Pink florets, 18-20 per spike.
10. Gazel: Pink florets with yellow throat; 14-18 florets per spike.
11. Grock: Blue florets with violet/purple throat; 16-18 florets per spike.
12. Jacksonville Gold: Yellow florets; 14-16 per spike.
13. Jwala: Vermilion florets with streaks; 14-18 florets per spike.
14. Manhar: Primrose yellow florets with pink splashes; 14-18 florets per spike.
15. Manisha: White florets with pink splashes; 14-16 florets per spike.
16. Manmohan: Yellow florets with purple splashes; 14-16 florets per spike.
17. Mohini: White florets with pink splashes; 12-14 florets per spike.
18. Mukta: Yellow florets with purple splashes; 12-15 florets per spike.
19. Meera: Snow white florets, early flowering; 18 florets per spike.
20. Phule Prerna: Pink shades on white petals; long vase life, 16 florets per spike.
21. Pitambar: Greenish-yellow florets with purple streak; 15-16 florets per spike.
22. Poonam: Light yellow florets; 17 florets per spike.
23. Pusa Unnati: Tall, with saffron red florets; 19-21 florets per spike.
24. Pusa Manmohak: Saffron red florets with white stripes; 19-21 florets per spike.
25. Pusa Srijana: Purplish-white florets; 15-16 florets per spike.
26. Pusa Red Valentine: Red florets with sunray-like lines; 18-19 florets per spike.
27. Pusa Vidushi: Purplish-white florets with purple spots; 15-16 florets per spike.
28. Sapna: Light yellow florets with green blotch; 17 florets per spike.
29. Shobha: Light pink florets with creamy throat; 18 florets per spike.
30. Shree Ganesh: Pale yellow to white florets; long vase life, 19 florets per spike.
31. Smita: China rose florets with darker margins; 14-15 florets per spike.
32. Triloki: China rose and yellow florets; 14-15 florets per spike.
33. White Goddess: White florets with purple throat; 17-20 florets per spike.

Propagation Methods

Gladioli can be propagated through seeds, corms, and cormels. Each growing season produces a new corm from the original one. Cormels, which are smaller corm-like structures, develop from the buds at the base of the new corm and grow on branched stolons. For commercial propagation, corms with a diameter of at least 4-5 cm are preferred, and they should be healthy and free from disease. Conical corms are favoured over flat ones for better flower quality. After harvesting the spikes, corms are lifted 6-8 weeks later, cleaned, and treated by dipping in a 0.3% Captan 50 WP solution for 30 minutes. They are then shade-dried in a well-ventilated area for about 15 days. Once dried, corms are packed in crates or net bags and stored in a cold environment at 3-7°C. Before planting, corms should be removed from cold storage one month in advance, kept in a well-ventilated area at room temperature, and their scaly outer layers removed. Finally, the corms are dipped in a solution of mancozeb (2g) or carbendazim (1g per litre).

Plantation Techniques 

For planting gladioli, prepare the soil by spading or ploughing to a depth of 30 cm. This should be done between September and October, with planting extending to November or even December. Remove the brown dry scales or tunics from the corms and disinfect them to prevent diseases. To extend the blooming period, use a mix of corm grades, stagger planting every 15-30 days, plant at varying depths (7.5, 10, 15 cm), and select early, mid-season, and late varieties. Healthy, disease-free corms with a diameter of 4-5 cm should be spaced 30 x 20 cm apart. Plant corms at a depth of 5-10 cm to avoid poor cormel production and decay. High-crowned corms generally perform better than flat ones.

Manuring and Fertilisation  

In preparation for planting, mix 20 tonnes/ha of FYM into the soil. Apply 120 kg N, 150 kg P2O5, and 150 kg K2O per hectare. Of this, 60 kg N along with the full dose of P2O5 and K2O should be applied as a basal dose. The remaining N should be applied in two split doses: first at the 4-6 leaf stage and second at 6-8 weeks after planting.

Water Management

Water management is crucial for growing quality gladiolus spikes. Ensure regular irrigation every 7-10 days, depending on weather conditions, and avoid overwatering. Do not allow the plants to suffer from water stress, especially when spikes are emerging. Withhold irrigation for 4-6 weeks before harvesting the corms.

Cultural Practices

After corms sprout, water as needed. When shoots reach about 20 cm, heap soil around them to a height of 10-15 cm. Earthing up is crucial 6-8 weeks after planting or before spike emergence to support upright growth and reduce weed competition, especially in light soils. Stake plants if they are prone to wind damage or weak stems. Use 1.5-meter stakes or strings stretched between stakes for support—stake plants when they are 15 cm tall to protect them from wind.

Protection of Gladiolus

Pests  

• Cutworms (Agrotis segetum): Larvae cut plants at ground level and damage corms and spikes. Summer ploughing exposes pupae to predators. Control with poison bait using carbaryl or malathion at 0.1%.
• Bulb Mite (Rhizoglyphus echinopus): Causes stunted growth and distorted leaves. Hot water treatment and proper sanitation are essential for control.
• Aphids: Several species suck sap from shoots, reducing flower quality and spreading viral diseases. Control with 0.1% malathion spray.
• Thrips (Taeniothrips simplex): Damage leaves and spikes, causing silver streaks and deformation. Control with Acephate 0.1% or contact insecticides.
• Loopers (Trichoplusia ni): Feed on leaves. Controlled by 0.2% dimethoate spray.
• Grubs and Beetles: Attack leaves and flowers. Control with 0.05% malathion spray.
• Nematodes: Damage corms and roots. Control with hot water treatment and soil fumigants.

 

Diseases  

• Fusarium Wilt (Fusarium oxysporum): Causes yellowing leaves and corm rot. Control by destroying infected corms, spraying Bavistin, and crop rotation.
• Leaf and Flower Blight (Curvularia spp.): Causes lesions on corms and leaves. Control with weekly mancozeb 0.2% spray.
• Neck Rot (Stromatinia gladioli): Causes stunted growth and rot. Control with hot water treatment and fungicide spray.
• Storage Rot (Penicillium gladioli): Treat corms with Benomyl 0.2% and ensure proper curing.
• Septoria Leaf Spot: Causes brown spots on leaves and corms. Control with copper oxychloride or carbendazim.
• Core Rot (Botrytis gladiorum): Causes dark brown corms and grey spores on leaves. Remove infected parts and spray with Maneb 0.2%.
• Stemphylium Leaf Blight: Produces yellow lesions on leaves. Control with mancozeb or copper oxychloride spray.
• Bacterial Scab and Blight: Dip corms in 1:100 mercuric chloride before planting.
• Root-Knot Nematodes: Cause wilting and root galling. Use nematode-free material, hot water treatment, and apply Furadan granules.

Harvesting and Storage 

Lifting of Corms and Cormels:  

After harvesting flowers or spikes, plants are allowed to mature until the leaves are yellow and dry naturally. Watering is reduced, and after 3-4 weeks, corms and cormels are lifted when 25% of the cormels turn brown, indicating maturity. Corms are carefully dug out, and checked for disease, and affected corms are discarded.

Curing:  

Post-harvest, corms and cormels are kept in trays in a shaded, well-ventilated area for about two weeks. Curing involves layering corms no more than three deep and keeping them at 21°C for five weeks.

Cleaning, Grading, and Storage:  

After curing, corms are cleaned, graded, and treated with 0.2% Captan or dusted with insecticides like Cythione or Dithane M-45. Corms are stored in perforated trays in a cool, dark room below 27°C. Cormels are stored similarly, with smaller ones stored at room temperature and larger ones requiring cold storage—periodic checks and turning to prevent rotting. Corms and cormels are removed from cold storage in early October and acclimated to room temperature for a week before planting.

Curing of Gladiolus Spike

Gladioli typically bloom 2–3 months after planting. Early varieties flower in 80–90 days, while late varieties take 100–145 days. Harvest the flower spike close to the base with a sharp knife or scissors once the first floret opens. Retain 4–6 basal leaves on each plant to ensure proper corm and cormel development for next year’s flowers. For the internal market, cut spikes when 1–2 lower florets have opened; for the external market, wait until mature unopened buds are fully coloured. Immediately after cutting, immerse the spike up to 15 cm from the base in a bucket of water.

Yield

The yield of gladiolus flower spikes and corms varies based on variety, corm size, planting density, and management practices. With a spacing of 30 x 20 cm, approximately 1,50,000 marketable spikes can be produced per hectare. Additional income can be gained from selling corms.

 

Wishing you a bountiful and prosperous gladiolus harvest! For further assistance or any queries, please feel free to reach out to your local agricultural experts @ Agrigo 24/7