Gladiolus sword lily
Height 30-120cm (1-4ft)
Planting distance 10-20cm (4-8in)
Flowers mid summer to mid autumn
Sunny sheltered position
Corms available late winter to
The showy flower heads of gladioli make them popular for cutting and exhibiting. Growing them as decorative plants in a border does have some drawbacks – the indivi-dual flower spikes last only two weeks and the plants often need staking. However, their bold form and colour compensate for this.
The original gladiolus species have now mostly been replaced by half-hardy hybrids. These showy hybrids are planted in spring, then lifted in autumn and stored in a frost-free place over winter. The few species gladioli still avail- able are hardy and can be planted in autumn and left in the ground right through the year.
Popular hybrids and species
The half-hardy hybrids are organized into four groups, according to size and flower shape. Large-flowered hybrids have 50cm (20in) long flower spikes consisting of roughly triangular florets. Coming in an enormous range of colours, they appear from mid summer to early autumn on l-1.2m (3-½ – 4ft) high stems. Gladioli in this group are best grown for general garden display and cutting. Popular hybrids include ‘Early Yellow’ (deep yellow), ‘Flowersong’ (bright golden-yellow), ‘Oscar’ (scarlet), ‘Peter Pears’ (soft-orange), ‘Shake-speare’ (lilac), ‘Sweepstake’ (salmon-pink) and ‘Traderhorn’ (scarlet with white blotches). Primulinus hybrids have 38cm (15in) long flower spikes composed of loosely arranged florets that bloom in mid and late summer. The top petal of each floret is hooded. They are free-flowering but less vigorous and smaller than the large-flowered varieties. These hybrids reach 60-100cm (2 – 3-1/2ft) high and are usually grown for cutting. Popular hybrids include ‘Columbine’ (shell-pink), ‘Robin’ (pink-red), ‘White City’ (white) and ‘Yellow Special’ (yellow).
Butterfly hybrids have 45cm (18in) long spikes of closely packed florets. Their petals are ruffled and they often have distinctive throat markings and blotches. They flower in mid and late summer on 60-90cm (2-3ft) high stems. Popular hybrids include ‘Bambino’ (carmine-pink), ‘Melodie’ (salmon-pink), ‘Prelude’ (red and white) and ‘Summer Fairy’ (salmon-red). Miniature hybrids have florets similar in arrangement to those of the primulinus hybrids, but smaller. The florets are usually ruffled and arranged on 38cm (15in) long spikes. They appear in mid and late summer on 45-75cm (1-½ – 2-1/2ft) high stems. The shorter hybrids are suitable for growing in mixed borders since they don’t require staking. All make excellent cut. Popular hybrids include ‘Bo Peep’ (apricot-salmon), ‘Dancing Doll’ (cream with salmon and scarlet blotches) and ‘Green-bird’ (sulphur-green florets with crimson throats). Gladiolus byzantinus, a hardy species, has 38cm (15in) long spikes of loosely arranged wine-red flowers which appear in early summer, sooner than most other gladioli. They stand 60cm (2ft) high.
Gladiolus x colvillei hybrids have loosely arranged white florets. ‘The Bride’ is pure white. Only 30-50cm (1-1/2ft) high, these delicate gladioli flower in mid and late summer.
Gladiolus nanus hybrids – which have been developed from species gladioli – come in shades of pink, rose or scarlet with violet to purple blotches. They stand 45-60cm (1-½ – 2ft) high and flower in mid and late summer.
Gladioli grow best in well-drained soil in a sunny position. As soon as the ground is workable, prepare it for planting. Dig in well-rotted manure, rake in some bone-meal and, if the soil is too heavy or too light, work in plenty of strawy manure. Cover the corms with 10cm (4in) of soil – slightly more on light soil – in early to mid spring. Make sure the base of each form is settled firmly in the soil -in heavy soil, set them on a base of sharp (gritty) sand to aid. For a succession of blooms through the summer, make three or four plantings at fortnightly intervals.
Gladioli for garden decoration in a mixed border should be planted in clumps; set the corms 10-15cm (4-6in) apart. Gladioli grown for cutting are best planted in single or double rows, 30-38cm (12-15in) apart.
Eight to ten weeks after planting, begin to water generously, particularly during dry periods after the flower spikes have appeared. Start to give liquid feeds regularly. Stake large-flowered hybrids and plants grown for exhibition in an exposed position. Arrange the stake on the side opposite to that of the developing flower spike. Secure the stem with raffia or wire rings.
When the foliage begins to turn yellow-brown in mid autumn, and before the first frost, lift gladioli corms with a fork. Clean soil off the corms, and cut off the main stem 1cm (Vfcin) above each. Take care not to bruise them. Dry off the corms for 7-10 days, then store in trays or shallow boxes in a cool, but frost-free place.
Break away and discard old shrivelled corms at the base of the new corm as soon as they will come away easily in your fingers. Pull off the tough outer skin on large corms and remove and store small cormlets for propagation. Check all corms during the winter and throw out any that show signs of disease. G. byzantinus, G. colvillei hybrids and G. nanus hybrids need not be lifted.
In winter, remove cormlets (resembling the size of a pea) produced at the base of the new corm. Plant in early spring in an outdoor nursery bed, setting them close together in drills 5-7.5cm (2-3in) deep, with a layer of sand below and above to help growth and make lifting easier in autumn. Keep the young plants weed-free and well watered.
When the leaves become discoloured in autumn, lift the cormlets and store them in the same way as adult corms. The following spring plant out and tend as before. Most cormlets reach flowering size in the second year; if they don’t, repeat storing and growing cycle for another year.
Pests and diseases
Thrips and aphids may infest corms in store, producing rough brown patches. Thrips may also infest growing plants, mottling the leaves and flowers. Stored corms may be affected by.