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Gladiolus Grandiflora hybrids

Garden Gladiolus
Iridaceae
Bulbs and bulblike plants, Perennials, Flowers

GLADIOLUS

All have sword-shaped leaves and tubular, often flaring or ruffled flowers in unbranched or branching, usually one-sided spikes. Have an extremely wide color range. Flowers come from spring to fall, depending on the kind of gladiolus and the planting time. Superb cut flowers. Good in borders or beds behind mounding plants that cover lower parts of stems, or in large containers with low annuals at base.

Plant corms of baby gladiolus in fall or early spring for flowers in late spring. Plant all others from midwinter (in mildest regions) into spring, after the soil has warmed. Grandiflora hybrids will flower about 100 days after planting; the smaller hybrids and species will bloom in about 80 days. For an extended flowering season, plant at 1- to 2-week intervals over a period of 4 to 6 weeks. Where the growing season is long enough, gardeners often time plantings so that bloom will be over before the onset of hottest weather, when thrips can seriously disfigure the flowers. 

Start off with corms that are high crowned for their width; broad, flat ones are older and less vigorous. Best planted in rich, sandy loam. Set corms about four times deeper than their height; plant somewhat more shallowly in heavier soils. Space big corms 6 in. apart, smaller ones 4 in. apart.

You can cut flower spikes when the lowest buds begin to open, but keep at least four leaves on the plants to build up corms. Corms can be left in the ground from year to year where plants are perennial (dig, divide, and replant when performance declines). After blossoms fade, trim off stems beneath the lowest flower—uncut stems will set seeds, diverting energy from food storage. In colder areas, dig after the foliage yellows completely (in rainy areas, dig while leaves are still green to avoid botrytis infection). Dry corms on a flat surface in a dark, dry area for 2 to 3 weeks; then store over winter in a single layer in flats or ventilated trays in a cool place (40° to 50°F/4° to 10°C).

Gladiolus hybrid
Gladiolus hybrid

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Gladiolus Grandiflora hybrids

These are the best-known gladiolus, producing spikes that reach from 3–6 ft. tall, depending on the variety and growing conditions. Late spring and summer flowers (up to 30 per spike) are widely flaring, up to 8 in. across; colors include white, cream, yellow, orange, apricot, salmon, red, rose, lavender, purple, smoky shades, buff, and even green. More diminutive selections from grandiflora breeding are grouped as small and miniature gladiolus; these grow 3–4 ft. high, stand upright without staking, and bear up to eighteen 2 1/2–3-in.-wide flowers per spike.

Though perennial, grandiflora hybrids are usually dug and stored yearly even in mild-winter regions.

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