Gladiolus is a tall plant producing large, bright flowers in a wide range of colors, including red, pink, orange, yellow, white and multicolored varieties. After summer, gladiolus flowers wither as the plant prepares for dormancy. Knowing the right way to prepare dormant gladiolus corms for winter is important, as providing too much or too little warmth will adversely affect the corms. Growers in U.S. Department of Agriculture Plant Hardiness Zones 7b and colder remove the bulbs from the ground to protect them from frost. In warmer Zones 8a and higher, removing corms is unnecessary because mulch can provide adequate protection over the winter.
Leaving the Bulbs in the Ground
Pinch off flowers as they fade. Cut back the flower stalks an inch away from the corms once they begin to show color changes to brown or yellow. Leave at least four leaves intact to feed the corm for blooms during the next season.
Mulch beds with a 2- to 4-inch layer of straw, hay or pine bark to prevent alternate freezing and thawing, which will damage corms. Begin mulching after the weather gets cold.
Remove the mulch after the danger of cold weather passes, in early spring. If the mulch is left on the ground after new growth, new shoots will be pale, weak or broken. Dispose of the mulch in a plastic trash bag to prevent spreading pests and diseases.
Removing the Bulbs for the Winter
Begin removing gladiolus corms from the ground when the foliage begins to show color changes to brown or yellow. Loosen the soil around the base of the plant with a hoe or your hands. Grasp the stem of the plant gently and pluck the gladiolas corm straight up from the soil.
Shake the excess soil off the corm. Twist the leaves from the top of the corm and discard of them. Place the corms on a screen that is elevated above the ground in partial sunlight. Allow the corms to dry in the sun for at least two days.
Put the bulbs in a plastic mesh bag in a well-ventilated room providing temperatures of about 45 degrees. Hang the bag above ground level to prevent introducing mold and mildew to the corms. Keep the corms in the mesh bag until danger of cold weather passes and they can be replanted in early spring.
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Things You Will Need
- Straw, hay or pine bark
- Plastic trash bag
- Plastic mesh bag
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