May be harmful if eaten by humans or animals – Keep away from children and pets
Active during: Summer
Common Name: Gladioli, sword lily
There are about 265 species, mostly from Western Cape in South Africa and sub-sahara Africa; as well as southern Europe, Middle East and western Asia.
Although some of the prettiest Gladioli occur amongst the approximately 70 Winter-growing species from the winter rainfall area of the Cape, the large-flowered, tall-stemmed modern hybrids have been derived largely from summer-growing South African species. There also exist several evergreen species. Unfortunately, most Gladioli species are rather difficult to grow. They are also susceptible to many diseases when cultivated. The following are some exceptions that make good garden plants:
- carneus (also known as painted lady) from the southern and western Cape has 4cm long funnel-shaped flowers. These vary in colour from white to cream, pink or purple, often with the lower lobes speckled with red, yellow or mauve. Sometimes the throats carry dark speckles. It flowers in spring or early summer.
- huttonii found naturally between Plettenberg Bay and Grahamstown has bright orange flowers and yellow streaked lower petals. Shorter than most species (40cm) it is easy to grow. G. liliaceus occurs naturally from Clanwilliam to Port Elizabeth has curled petals in brown to orange. Has a strong fragrance at night.
- tristis has been used in hybridizing very successfully. Cream coloured flowers with brownish green keels. They have a strong fragrance at night and are tall growing.
- dalenii is the most common species in gardens. It can be grown successfully in Summer or Winter rainfall areas. It generally blooms in late summer but it will adapt to spring flowering in winter rainfall areas. Known as the Rhodesian Gladiolus, G. dalenii occurs all along the eastern escarpment of southern Africa, from the Eastern Cape right into tropical east and central Africa. The large, hooded flowers are usually bright red or orange, but may be mottled with yellow, green and purple. It needs a sunny or slightly shaded position.
- saundersii is easy to grow if it receives plenty of water during summer. It has large, bright vermilion blooms, of which the three lower lobes are speckled crimson on a white background, borne on stems nearly 1m tall. Dormant during winter, when it must be kept absolutely dry.
- geardii produces pink flowers on short stems in mid- summer. Prefers light shade.
- mortonius flowers during late summer to early autumn with frilly pink petals. Full sun.
The tall, stately Gladiolus we know so well are modern, large flowered hybrids derived from G. cardinalis, G. carneus, G. cruentus, G. dalenii, G. oppositiflorus, G. papilio and G. tristis. These beautiful hybrids combine the best attributes of these species and are easy to grow. They flower during summer at a height of about 1m and you can have them flower in batches, at specific times from early summer right up to the onset of winter. If you live in a frost-free area, you can flower them year-round. Refer to the section on timing bulbs at home for details.
Gladioli look magnificent towards the back of a mixed perennial border. Groups of about 25 look best, although groups of 10 in single colours also make a bold statement. The soil should first be loosened to a depth of 20 cm. Gladioli like a well-drained sandy loam, preferably slightly acidic. Winter- growers need extra drainage and a very high concentration of well- draining sand in the medium. Sterilized soils are preferred for many species to avoid fungal infections. Summer- growers should have a little extra compost worked in for water retention. All Gladioli dislike heavy clay soil with poor drainage. No fresh manure should be added at all. The underside of the corm is the flat side with the “belly-button” indentation. Gladioli need a full-sun position to flower successfully. If your Gladioli are planted where wind may be a problem, they may need staking.
Glads are very rewarding and relatively inexpensive. Watering is very important – do not allow the sub- soil to dry out at all during the growing season – not even once! From the time the foliage is approximately 20 cm above ground, well before the floral buds become visible, Gladioli should be sprayed against insects and fungal rust on a weekly basis. In many areas thrips is a serious pest on summer- growing Gladioli. Usually grey spots and damaged leaves and flowers are noticed before the insects themselves are visible. They can cause flowers to fail to open. Red spider mites may also attack during dry hot weather. Aphids and mealy bug can also appear. Regular preventative spraying will keep these pests under control, and ensure flowering. Yellowing leaves during active growth may indicate fusarium rot which requires drenching with an appropriate fungicide. Blotches on the leaves during the growing season usually indicates the presence of botrytis and should be treated early on with an appropriate fungicide spray. Badly affected leaves should be cut off and discarded (not in the compost heap). God air circulation helps prevent botrytis attacks. If your Gladiolus is planted where wind may be a problem, they may need staking. Gladioli can be tricky to keep for successive seasons and so many gardeners discard the corms after flowering. If you do not intend to re-grow the plants, pull them up entirely, corms and all, after flowering. Do not add any old flowers, foliage or corms to the compost heap as this will infect future plantings with diseases and pests which may be harbored on the old plants, although perhaps invisible at the time you discard them. Such pests and diseases may include rust spores, mildews, bacteria, nematodes, mites and eggs of other pests. These will all survive in the compost heap and lie in wait to infect your garden as they enter it with a batch of compost. If you wish to keep your corms for the following season cut off spent flower stalks just below the flowers. Keep the plants growing by regular deep watering and feeding with bulb food from time to time after flowering. A dressing or two of potassium sulphate between flowering time and lifting will also benefit the corms. Lift the corms as soon as the foliage has yellowed. Cut off the stem and its foliage just above the new corm which has formed directly above the old corm. Discard the old corm – it will not grow again. Wash the new corms and little cormlets in water. Inspect the corms for damage and black spots and discard any which do not look 100% perfect. Corms with spots will harbor diseases, which will spread not only in the affected corms themselves, but to neighboring corms, both in storage and in the ground. Dry the corms thoroughly for at least a week in the shade and then dust with an insecticide and a fungicide. It is recommended to rotate the planting location from season to season to allow mentioned diseases time to “vacate” the affected soil.