Planting Instructions by Flower Name
- Hardy Zones: 7-10
- Spacing: 5-6"
- Height: 36-48"
- Blooms: summer to fall
- Planting Depth: 4-5"
Gladiolus, or glads, are in the Iris family. They have sword-shaped leaves and funnel-shaped flowers that grow on tall spikes and make excellent cut flowers. Twilight Glads will produce blooms of velvety blue-violet, accented by purplish-black throats.
Plant bulbs in a sunny location, 4-5” deep and 5-6” apart in rich, well-drained soil. Plant the tapered end pointing up, and the flatter side down. There are often dried roots on the “down” side. To prolong the bloom season, plant a small group of bulbs every couple weeks from spring to late June.
Apply a balanced liquid fertilizer every ten days from the time the flower buds appear until they begin to bloom. Flowers will open at the bottom of the flower stalk first. Use plant supports to keep the stalks straight and protect from wind damage.
Gladiolus are hardy only in USDA zones 7-10. In zone 7, apply a few inches of mulch in late autumn to increase the hardiness of the bulbs. In zones 6 and colder, you must lift the bulbs if you want to plant them again next year. Dig up the bulbs 6 weeks after blooming or when the foliage yellows. You will see an on old withered corm, with a new one on top and smaller ‘cormels' in between. Leave everything intact and allow to dry in a warm area for a few days. When dry, cut off the foliage, leaving about an inch of top growth. Wipe off any soil and remove the old withered corm at the base, as it will not bloom again. Store the new corms over the winter in a dry, cool place (40-55°F) in a paper or netted bag. Dust the bulbs with sulfur or another fungicide to prevent fungal diseases. Plant again the following spring, once soil is warm and workable.