Gladiolus

The elegant Flower Spikes of Summer

An orange and red bicolour hybrid gladiolus.

Yellow glads in a mixed border looks fab.

Pure white satin blossoms are literally brilliant.

Gladiolus need full sun.

Traderhorn gladiolus.

Flowers open at the bottom of flower spikes.

A fuchsia pink ruffled hybrid glad.

Flower spikes become top heavy when the bottom flowers fade.

A sunshine yellow hybrid.

Gladiolus are excellent cut flowers.

Common Name: gladiolus
Botanical Name: Gladiolus
Family: Iridaceae
Plant Type: summer bulb
Form: upright, fan shaped, erect
Mature Size: 1.5’ – 6’ x 1’ - 2’
Growth: fast
Origin: South Africa
Hardiness Zone: 7 to 10
Foliage: green, stiffly upright, linear, narrow, sword-shaped, longitudinal groove along length of leaf
Flowers: showy, funnel shaped with 6 flared petals along leafless spikes, miniatures blooms less than 3”, hybrids 5”, white, reds, yellows, purples, orange, pinks, salmon, bicoloured, June to September
Fruit: insignificant
Exposure: full sun
Soil: prefers humus rich, well-drained moist soil
Uses: containers, borders, cut flowers
Attracts: bees, butterflies, hummingbirds and other pollinators
Invasive Tendencies: no
Propagation: cormels
Pruning: cut of flower stalks after flowering
Problems: fusarium wilt, grey mould, viruses, thrips, aster yellows

Comments:
Elegant gladioli flower spikes are a dramatic and a welcome contrast to summer’s billowing shrubs. Previously referred to as ‘sword lilies’ due to their grooved lance-shaped foliage, they are a colourful addition to sunny borders.

Gladiolus funnel shaped blossoms bear petals as soft as satin in shades of red, pink, salmon, purple, blue, yellow, white, orange and green. Flowers alternate along the flower stem with the lower ones opening first. Each tubular blossom has six flared petals with nectar and pollen that attracts hummingbirds, bees, butterflies and other pollinators.

Most glads grow to a height of 2 to 5 feet, but there are also small, 3” flowered miniature hybrids that are perfect for containers. Alternately, large grandiflora hybrids with 5” flowers that need staking.

Since it takes between 60 to 90 days for gladiolus to bloom, start corms indoors. Alternately plant outside after the danger of frost has passed and the soil has warmed to 13°C (55°F). For a succession of blossoms, plant corms every 10 days.

Gladiolus grow from corms, modified underground stems resembling a flattened bulb. Corms shrivel by the end of the season and are replaced by a new one underneath. Corms may remain in the ground in USDA Zones 7 to 10, however, it is recommended to dig them up it’s fall and store them indoors.

Purchasing & Planting Gladiolus
Select healthy spot free, firm corms. The larger the corm, the bigger the flower as they are more mature. To plant gladiolus, select an area where they will receive at least 6 hours of direct sun per day in a protected area away from strong winds. They do not like dry soil so mix in a few inches of compost, SeaSoil or another organic matter. Avoid areas that don’t drain well as the corms to prevent rotting.

Plant corms 4-6 inches deep and 5-6” apart, pointed end up and press them firmly into the ground. To provide cut flowers, plant them in rows for easy cutting, otherwise, plant in groups of seven or more for the best display. Add a stake for each corm to provide support for their long, top heavy flower stalks. Water well after planting and add a 3-inch layer on top of the soil to hold in moisture and deter weeds. Provide consistent moisture during periods of drought during the summer.

After Flowering
Cut off the flower stalks after their flowers fade but keep their leaves intact as they provide food for next year’s blossoms. Before significant frost occurs, dig up corms, shake off the excess soil, then cut off their stems and foliage. Snap off the dead corms from the bottom of the new ones and discard. Discard or keep the tiny cormels at the base of the mother corm. Although the cormels will eventually flower, it is a lengthy process.

Cure the corms and cormels in a sunny dry area for a couple of days. Shake off any remaining soil then place in a single layer in a flat box for 2 to 3 weeks in warm and airy location. Coat the corms with a generous amount of cinnamon. It is a natural and effective fungicide. Place the dusted corms in a cardboard box, pantyhose, paper or cloth bags. Hang the bags and pantihose so air can circulate. Store in a cool, 2° to 7°C (35° to 45°F) garage or basement.

Winter hardiness
Gladioli are hardy from USDA Zone 8 to 10, however, with a good thick mulch they will survive winters in Zone 7. Otherwise, dig them up after their foliage has yellowed and before temperatures dip below -2°C (28°F).