The Gladiolus (Gladiolus × hybridus), also known as Sword Lily, is an ornamental plant widely cultivated in tropical, subtropical, and temperate regions, prized for its large, symmetrical flowers arranged on vertical spikes. Its importance in landscaping and floriculture is due to its ability to add beauty to gardens, flower beds, and bouquets, being one of the most commercially traded cut flowers worldwide.
The etymology of the genus name “Gladiolus” traces back to Latin, where “gladius” means “sword,” referring to the plant’s long, narrow leaves, which resemble sword blades. The suffix “-olus” is a diminutive, resulting in “gladiolus,” or “little sword.” This nomenclature was adopted by Pliny the Elder in Ancient Rome and reflects the distinct morphology of this magnificent plant’s leaves.
The name Gladiolus × hybridus reflects the hybrid nature of this plant, with the term “hybridus” derived from Latin, indicating its origin from crosses between different species. The inclusion of the “×” symbol before the specific epithet denotes that it is an interspecies hybrid. The genus Gladiolus belongs to the Iridaceae family and consists of approximately 300 species, mainly distributed in Africa, Europe, and the Mediterranean region.
The history of cultivated Gladiolus dates back to the early 19th century when the first hybrids were developed in Europe. Yes, the hybrid Gladiolus we know today is the result of complex crossings between various species of the genus Gladiolus, predominantly originating from the southern part of the African continent. These species contribute specific characteristics, such as disease resistance, variety of colors and floral shapes, adaptability to different climates and soils, as well as influencing the size and flowering time.
The modern cultivated Gladiolus is the result of a long hybridization process initiated in the 19th century. Throughout this period, various wild species of the genus Gladiolus were crossed with the aim of selecting larger, more showy flowers with better adaptation to cultivation. The species most frequently involved in the creation of modern hybrids include G. dalenii, G. oppositiflorus, G. papilio, G. cruentus, G. saundersii, and G. orchidiflorus.
In 1823, in England, the Colville Nursery crossed Gladiolus tristis with Gladiolus cardinalis, resulting in the hybrid known as Gladiolus × colvillei. Other hybrids that stood out in the 19th century include G. × ramosus, G. × nanus, and G. × gandavensis. The latter played a crucial role in subsequent breeding, as it was widely used as a genetic base for crossbreeding in Germany, England, and the United States.
Through it, hybrids such as G. × leichtlinii, G. × childii, and G. × princeps emerged, progressively incorporating desirable characteristics such as hardiness, larger flower size, and new hues. The genetic complexity of these crosses increased from 1910, when the crosses between the available hybrids for horticultural improvement hardly included a wild species. Thus, these commercially available hybrids could no longer have their origins attributed to any single species, nor was it possible to identify the parental species, consolidating the use of the names Gladiolus × hybridus, Gladiolus x grandiflorus, and Gladiolus x hortulanus to encompass current cultivars.
However, it is important to consider that the Gladiolus species used in the origin of modern hybrids are predominantly African, especially from South Africa, which hosts the greatest diversity of the genus. These native species grow in varied habitats, including open grasslands, mountain slopes, and Mediterranean climate regions with dry summers and rainy winters. Their adaptability to these environments contributed to the selection of cultivars resistant to different soil and climate conditions. The diversity of natural habitats of these ancestral species is one of the reasons why the hybrid Gladiolus has adapted so well to cultivation in temperate and subtropical regions of the world.
Current hybrid Gladiolus are classified into different groups based on characteristics such as flower size, blooming season, and ornamental use. The main cultivated groups are:
- Grandiflora: Gladiolus from the Grandiflora group are known for their large and showy flowers, with diameters ranging from 4 to 6 inches (10 to 15 cm). The floral spikes are dense and can reach up to 6 feet (1.8 meters) in height, containing up to 30 flowers per stem. These plants are widely used in the commercial production of cut flowers due to their imposing presence and variety of colors. However, they are less resistant to cold, and in regions with harsh winters, the corms must be removed from the soil and stored properly during the winter. Notable cultivars include ‘White Prosperity’, with pure white flowers and wavy petals, and ‘Nova Lux’, with vibrant yellow coloring. The main parental species involved in the origin of the Grandiflora Gladiolus are Gladiolus dalenii, G. cruentus, and G. oppositiflorus.
- Primulinus (or Dalenii Hybrids): The Primulinus group, also known as Dalenii Hybrids, features smaller, hood-shaped flowers arranged more sparsely on spikes ranging from 24 to 47 inches (60 to 120 cm) in height. These plants are more delicate and less demanding in cultivation, suitable for residential gardens. They have moderate cold resistance, able to survive the winter in hardiness zones 6 and above. Notable cultivars include ‘Las Vegas’, with yellow flowers and red edges, and ‘Carolina Primrose’, with soft yellow coloring. The main parental species involved in the origin of the Primulinus Gladiolus is Gladiolus dalenii.
- Nanus: Gladiolus from the Nanus group are short, generally between 18 and 24 inches (45 to 60 cm) in height, with small flowers 1.6 to 3.1 inches (4 to 8 cm) in diameter. They are ideal for cultivation in pots, borders, or areas with strong winds. This group is more resistant to weather conditions and blooms more quickly, also suitable for colder climate regions. Notable cultivars include ‘Elvira’, with white flowers and red spots, and ‘Nathalie’, with soft pink coloring. The main parental species involved in the origin of the Nanus Gladiolus are Gladiolus cardinalis and G. ramosus.
- Miniature: Miniature Gladiolus are scaled-down versions of the Grandiflora, with smaller flowers, generally between 1.4 and 2.4 inches (3.5 to 6 cm) in diameter, and shorter spikes. They are suitable for small floral arrangements and cultivation in limited spaces. Despite their reduced size, they maintain the variety of colors and shapes of the larger flowers. Notable cultivars include ‘Charm’, with purple flowers and a cream throat, and ‘Robinette’, with cherry red coloring. The main parental species involved in the origin of the Miniature Gladiolus are Gladiolus carneus and G. tristis.
- Wild Species and Derived Hybrids: In addition to the groups mentioned, there are Gladiolus derived directly from wild species or their hybrids. These plants are valued by collectors and in naturalistic gardens due to their more delicate appearance and cold resistance. Examples include Gladiolus communis subsp. byzantinus, with vibrant magenta flowers, and Gladiolus murielae (formerly known as Acidanthera bicolor), with white flowers and wine-colored spots.
Gladiolus is a herbaceous geophyte with a perennial cycle, predominantly annual in commercial cultivation. The plant’s underground structure is formed by a corm, a modified stem of firm consistency, rounded to slightly flattened, covered by brown, leathery or fibrous tunics, resulting from the leaf sheaths of previous cycles. This corm functions as a storage and regeneration organ, producing apical shoots that originate the aerial part each cycle. The new corm forms above the old one, while the latter is progressively absorbed. Moreover, the plant develops lateral cormels—smaller vegetative propagation structures protected by thick tunics, ensuring the clonal perpetuation of the cultivar.
The root system is fasciculated, composed of unbranched adventitious roots originating at the base of the corm, usually after initial sprouting. These roots are absorptive and temporary, being replaced each new cycle. Gladiolus do not form rhizomes, do not have specialized tuberous roots, and the plant relies entirely on the corms for regeneration.
The aerial part of the Gladiolus consists of an erect, simple, and unbranched stem, with a herbaceous texture and firm consistency, which can reach from 24 inches (60 cm) to over 4.9 feet (1.5 m) in height, varying according to the cultivar. This stem, also called a floral scape, emerges from the corm as a cylindrical to slightly laterally flattened structure, with light green or greenish coloration with purplish tones in some varieties. The consistency of the stem is herbaceous, yet rigid enough to support the inflorescences. In Grandiflora type cultivars, due to the size and weight of the flowers, staking is commonly required in commercial cultivation.
The leaves of the Gladiolus are simple, alternate, arranged in a distichous spiral, and concentrated at the basal portion of the plant, emerging directly from the corm in a fan shape. They are linear to lanceolate in shape, with an acuminate apex, tapered base, and entire margin. The venation is parallel, typical of monocots, with a vertical arrangement and longitudinal vascular bundles. The length of the leaves can vary from 12 to 35 inches (30 to 90 cm), and the width from 0.8 to 2.4 inches (2 to 6 cm), with slight variation among the Grandiflora, Primulinus, and Nanus groups. The upper leaves are smaller and partially envelop the floral scape. The leaf surface is glabrous, with a smooth texture and medium to dark green coloration, without pubescence. There is no formation of a petiole, as the leaves are sheathing with a well-defined sheath.
The inflorescence is a type of spike, terminal and unilateral, meaning the flowers predominantly develop on one side of the stem. This spike can contain from 10 to 30 flowers, depending on the group and cultivar. The organization of the flowers follows an ascending sequential order, that is, the lower flowers open first, followed by the upper ones. Bracts are present, green or greenish, membranous, partially enveloping the floral buds until anthesis.
The flowers are hermaphroditic, exhibiting zygomorphic (irregular) symmetry, with six tepals arranged in two whorls, fused at the base forming a perigonial tube. The dorsal tepal is more developed and curved over the stamens, acting as a “hood,” especially pronounced in cultivars from the Primulinus group. The flowers are not resupinate and vary widely in coloration, from pure white, yellow, pink, orange, green, purple, red to dark shades of purple, wine, or almost black, including bicolor and marbled variations.
The stamens are three, inserted in the floral tube, with free filaments and dorsifixed anthers, which release abundant and light-colored pollen.
The ovary is inferior, trilocular, with numerous ovules in each locule, and the style extends beyond the floral tube, branching into three linear or club-shaped stigmas, often visible among the upper tepals.
The species is monoecious with perfect flowers, meaning each flower possesses both male and female reproductive structures simultaneously. Pollination primarily occurs through insects (entomophily), attracted by the vibrant colors, flower shape, and presence of nectar. In commercial cultivars, self-pollination is common, but in genetic improvement programs, controlled manual pollination is often carried out.
The fruit of the Gladiolus is a dry, trilocular, dehiscent capsule that opens through three longitudinal slits releasing numerous seeds. The seeds are small, flat, light brown in color, with winged edges that facilitate their anemochoric (wind) dispersion.
The growth and flowering period of Gladiolus × hybridus varies according to the varietal group, latitude, and local edaphoclimatic conditions. In temperate climate regions of the northern hemisphere, planting of corms generally occurs between March and May, with flowering from June to September. In the southern hemisphere, planting preferably takes place between August and October, with flowering from December to March.
Cultivars from the Grandiflora and Primulinus groups are sensitive to cold, requiring temperatures above 50°F (10°C) for sprouting and complete their cycle between 90 and 120 days after planting. Meanwhile, Gladiolus from the Nanus group and hybrids with wild species adapted to Mediterranean and subtropical climates, such as Gladiolus communis subsp. byzantinus, show greater tolerance to low temperatures and can be cultivated in regions with cold winters, completing the vegetative cycle in 70 to 90 days. Proper selection of the group based on the expected flowering time is crucial for planning the harvest, staggering production, and seasonal landscape composition.
Gladiolus is highly valued in landscaping for its striking vertical structure, variety of colors, and adaptability to different garden styles. Its presence provides a significant visual impact, especially when used in mass plantings, arrangements with other plants, or borders.
In formal gardens, Gladiolus are often planted in rows or dense clusters, creating floral walls that delineate paths, fences, walls, or specific areas. Their variable height, depending on the cultivar, allows for layered compositions, with taller Gladiolus in the back and shorter varieties in the front. In informal or cottage-style gardens, they can be combined with other perennials and annuals, such as dahlias, zinnias, and cosmos, providing an effect of exuberance and diversity of colors and textures.
For small spaces or balconies, Gladiolus from the Nanus group are ideal due to their compact size and hardiness. They adapt well to pots and planters, as long as they receive direct sunlight for at least six hours a day. Moreover, in regions with mild climates, some varieties can remain in the soil over the winter, returning the following spring, which reduces the need for annual replanting. The choice of planting location should consider protection against strong winds, which can damage the floral stems. In exposed areas, the use of supports or planting near fences and walls can provide the necessary support.
In the realm of floriculture, Gladiolus stands out as one of the most popular cut flowers, appreciated for its durability, variety of colors, and stateliness. It carries a strong symbolism of integrity, inner strength, and remembrance, often used in occasions that celebrate achievements, honors, or mark farewells, such as graduations. Its erect and imposing form reinforces the message of respect and admiration, making it an expressive choice in formal and solemn compositions.
The floral stems, which can reach up to 4.9 feet (1.5 meters) in height, are composed of multiple flowers arranged in a spike, providing volume and elegance to floral arrangements. In vertical arrangements, Gladiolus are often used as a central or highlight element, providing height and structure. Their combination with flowers of various shapes and sizes, such as lilies, roses, and chrysanthemums, allows for balanced and harmonious compositions. Additionally, the chromatic diversity of Gladiolus facilitates their integration into thematic or seasonal arrangements.
To maximize the longevity of flowers in arrangements, it is recommended to cut the stems when the lower buds are about to open, preferably during the cooler hours of the day. Removing the lower leaves and immediately immersing them in clean water aids in hydration and prevents wilting. Regularly changing the water and cutting the stems diagonally every two days also contribute to the flowers’ longevity.
Besides traditional arrangements, Gladiolus are used in creating composite flowers, such as the glamelia, a technique that involves assembling a single flower from Gladiolus petals, resulting in a structure similar to a camellia. Although more complex, this approach offers a creative and sophisticated alternative for bouquets and special arrangements.
The versatility of Gladiolus, combined with their beauty and symbolism, makes them a frequent choice for various occasions, from festive celebrations to formal ceremonies, consolidating their prominent position in floral art.
For full development, Gladiolus need direct sun exposure for at least 6 hours a day (6 hours). Intense sunlight is essential for the formation of robust floral stems and brightly colored flowers. In partially shaded environments, development may be compromised, resulting in smaller flowers and more fragile stems.
They perform best in temperate to subtropical climates, with daytime temperatures between 70°F and 80°F (21°C and 27°C) and nighttime temperatures between 50°F and 59°F (10°C and 15°C). Temperatures below 50°F (10°C) can slow growth, while temperatures above 86°F (30°C) can cause thermal stress, adversely affecting flowering. Gladiolus from the Grandiflora group are sensitive to frost and do not tolerate temperatures below 30.2°F (-1°C). In regions with harsh winters, it is necessary to remove the corms from the soil before the first frosts and store them properly during the winter. On the other hand, Gladiolus from the Nanus group and hybrids with wild species, such as Gladiolus communis subsp. byzantinus, show greater cold tolerance, withstanding temperatures down to 15.8°F (-9°C).
Gladiolus prefers well-drained, fertile soils rich in organic matter, with a pH between 6.0 and 6.5. Heavy clay soils should be avoided or improved by adding coarse sand and organic compost to facilitate drainage. The presence of organic matter, such as worm humus or well-decomposed compost, is beneficial for plant development. In pots or planters, a mix consisting of 50% commercial ornamental plant potting mix, 30% vermiculite or perlite for aeration, and 20% organic compost is recommended. This composition ensures good drainage, moisture retention, and adequate nutrient supply.
Planting of the corms should be done in spring, after the risk of frost, when the soil temperature reaches at least 55°F (13°C). The corms should be planted with the tip facing up, at a depth of 4 to 6 inches (10 to 15 cm), depending on the size (the larger the corm, the deeper it should be planted). The ideal spacing between corms is 6 to 8 inches (15 to 20 cm), allowing good plant development and facilitating air circulation. For continuous flowering, staggered planting every two weeks during spring and early summer is recommended. You can buy all the bulbs together, and store them in the refrigerator, in a paper bag, in the vegetable drawer, while you plant them.
After planting, it is essential to keep the soil uniformly moist, without waterlogging. During the active growth period, watering should be regular, especially during dry spells, ensuring that the soil remains slightly moist. Avoid watering the leaves and flowers during irrigation to prevent fungal diseases.
Fertilization should be balanced, using fertilizers with an NPK ratio of 10-10-10 or 8-8-8. Apply an initial dose at planting and reinforce fertilization every 4 weeks during the growth cycle. Avoid excess nitrogen, which can promote vegetative growth at the expense of flowering.
Gladiolus cultivars with long and heavy flower stems may require staking to prevent lodging. Bamboo stakes or specific plant supports can be used, carefully securing the stems to avoid damaging the tissues.
After flowering, the flower stems should be cut at the base, allowing the plant to direct energy towards the development of the corms. The leaves should be left until they naturally yellow, indicating that the nutrients have been translocated to the corms. In regions with cold winters, the corms should be dug up after the foliage has senesced, cleaned, and stored in a cool, dry, and ventilated place until the next planting.
Gladiolus is generally avoided by deer, making it a viable option in areas with the presence of these animals. However, in situations of food scarcity, deer may consume Gladiolus, requiring additional protective measures.
The plant is susceptible to various pests and diseases that can affect its development and ornamental quality. Among the most common pests are thrips, especially the gladiolus thrips (Thrips simplex), which cause damage to flowers and leaves, resulting in discoloration and deformations. Other pests include aphids, mites, scale insects, borers, caterpillars, and nematodes, which can compromise the plant’s vigor and corm formation.
Concern for pests and diseases is not limited to plants in the vegetative stage, as stored corms can also be susceptible and create an environment conducive to the spread of pests and diseases. Fungal diseases pose a significant threat to Gladiolus cultivation. Corm rot caused by Fusarium oxysporum f. sp. gladioli is one of the most destructive, leading to plant wilting and corm deterioration. Other diseases include leaf spot by Curvularia, gladiolus rust (Uromyces transversalis), and dry rot by Stromatinia gladioli. Additionally, viruses such as cucumber mosaic and bean yellow mosaic can infect Gladiolus, causing symptoms such as chlorosis, deformations, and reduced flowering.
Prevention and management of these pests and diseases involve practices such as crop rotation, the use of healthy and treated corms, the removal of infected plant debris, maintaining adequate spacing between plants, proper storage of corms, and the application of fungicides and insecticides when necessary. Regular inspection of plants and the adoption of integrated control measures are essential to minimize negative impacts on the cultivation of Gladiolus.
The propagation of Gladiolus is predominantly carried out through corms and their cormels, ensuring the maintenance of the genetic characteristics of the cultivars. The main corms, after the flowering cycle, produce lateral cormels that can be separated and cultivated to generate new plants. These cormels generally take 2 to 3 years to reach the size and maturity required for flowering.
Propagation by seeds is possible, but less common, due to the genetic variability of the resulting plants and the prolonged time until flowering, which can vary from 3 to 5 years. This method of propagation is generally used in genetic improvement programs for the development of new cultivars with desirable characteristics.
The average time from planting the corm to flowering varies depending on the cultivar and growing conditions, ranging between 70 and 120 days. Short-cycle cultivars, such as those in the Nanus group of Gladiolus, can flower in approximately 70 days, while cultivars from the Grandiflora group may require up to 120 days to complete their cycle.
