Gladiolus

Iridaceae

Corn Flag, Sword Lily

They have slim, linear, pointed, dark green leaves which are ribbed. Whilst the natural species have relatively small flowers, the many commercially produced cultivars and hybrids have large and flamboyant flowers which are produced on thick stems and all face the same direction.
 

Uses

Cut flowers, border plants, fence lines, or greenhouse plants and summer border plants in cooler climates.  
 

Culture

These are hardy bulbous plants and they are widely grown in many countries. Provided the soil is well-drained, they adapt to most soils from clays to sands. The soil pH should be around 6.0 to 7.0. When adding compost or manure, lime is also often added to stop the pH dropping too low. In frost-free warm climates they can be grown all year round and left in the ground. In cooler areas, plant in spring after the frosts have finished. The shoots emerge 2 weeks after planting and take 80 to 90 days to flower. Pick the flowers when the bottom flower starts opening. Leave the corms for 4 weeks after picking flowers then lift the corm, dust with a fungicide, and store dry. Avoid wind damage by tying plants to stakes, or with the aid of a windbreak. Plant in a sunny position.
 

Propagation

They may be propagated from small cormlets divided from the main corms in autumn after the leaves have yellowed. They should be planted in spring and will take several years to produce flowers. Alternatively, they may be grown from seeds planted in spring. These also take several years to produce flowers but are often not true to type. 
 

Cultivars

A large number of named cultivars as well as species are grown, including:

G. x colvii (Scarlet Gladiolus) - to 60cm tall. The scarlet-red summer flower spikes are to 25cm long. Individual flowers have a yellow throat and are up to 7.5cm wide. There are many cultivars with different flower colours.

G. 'Golden Standard' - a large-flowered hybrid to 60-120cm tall. These have a 50cm long flower spike and individual golden-yellow flowers to 10-17cm wide. 

G. 'Madame Butterfly' - a butterfly hybrid to 130cm tall. These have individual flowers to 5-10cm wide which are a lustrous shell pink colour with salmon and mauve throats.

G. 'Richard Unwin' - a primulinus hybrid to 100cm tall. These have loose flowers in a flower spike to 40cm long. Individual flowers have a hooded top petal and are velvet-like chestnut red with cream stripes.  

 

Plant Health

Iron deficiency is a common problem. Diseases include various rots such as core rot of stored corms. Other diseases include gladiolus scab which causes red spots on leaves and death of plants in wet conditions, gladiolus dry rot which causes blackened spots and lesions and eventual death, and gladiolus yellows which causes yellow stripes on the leaves followed by dieback. They are also susceptible to virus diseases such as cucumber mosaic virus which may cause white marks on the flowers or chlorosis of the leaves. Aphids and thrips are problem pests which may infest stored corms or growing plants. Caterpillars may also eat corms or upper plant parts. 
 

More info

There are around 260 species most of which originate from Africa, particularly South Africa. Around 10 species originate from Mediterranean Europe and Asia.  

 

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