Home Bulbs Gladiolus in Cold Climates: A Mystery Solved | Growing Guide & Tips

Gladiolus in Cold Climates: A Mystery Solved | Growing Guide & Tips

by Donna
4 minutes read

Gladiolus: A Flower of Elegance and Mystery

Gladiolus, often called “glads,” are known for their tall, showy spikes of colorful flowers that resemble delicate orchids. These elegant blooms add a touch of beauty to any flowerbed, and they also make spectacular cut flowers.

Growing Gladiolus: A Love Story

I have a special fondness for gladiolus because they remind me of my mother. She had a “secret” for growing them: plant them near the dryer vent. She believed the heat from the dryer would warm the soil and help the gladiolus corms survive the winter in the ground.

Gladiolus in Cold Climates: A Mystery Solved

Traditionally, gladiolus are considered winter hardy only in zones 8 and warmer. However, I’ve been able to leave my gladiolus bulbs in the ground over winter in zone 6, and they’ve not only survived but also propagated nicely.

I wondered why this was possible. My mother’s theory seemed logical, but I questioned whether the heat from the dryer vent could really prevent the corms from freezing.

After some research, I discovered that there are types of gladiolus that are more cold-tolerant than others. Hardy gladiolus (Gladiolus nanus) are winter hardy in zones 5 to 7. They are smaller than other types of gladiolus, maturing around 20 inches (50 cm.) tall.

Could I have planted hardy gladiolus? No, my glads more closely resemble the Grandiflora hybrids, which are not as cold-tolerant.

I also found that there are types of gladiolus which originated in Europe and these tend to be hardier than those native to Africa. Could crossbreeding produce hybrids which are more cold-tolerant?

Cold-Tolerant Glads: A Growing Phenomenon

I’m not the only gardener who has experienced gladiolus surviving the winter in cold climates. Other gardeners have reported the same thing, with some even saying that their gladiolus corms have survived in zones 5 and 6.

Some people believe that global warming is playing a role in the increased hardiness of gladiolus. Others credit thick layers of mulch or the creation of microclimates, such as the one created by my mother’s dryer vent.

Whatever the reason, one thing is certain: If you’re a northern gardener wondering, “Can I leave gladiolus bulbs in the ground overwinter?” The answer might be yes!

Tips for Growing Gladiolus in Cold Climates

Here are some tips for growing gladiolus in cold climates:

  • Choose hardy varieties, such as Gladiolus nanus or European-origin varieties.
  • Plant the corms in a sunny location with well-drained soil.
  • Plant the corms 4-6 inches deep and 4-6 inches apart.
  • Water the corms regularly, especially during dry spells.
  • Fertilize the gladiolus plants monthly with a balanced fertilizer.
  • Deadhead the spent flowers to encourage new blooms.
  • In cold climates, dig up the gladiolus corms in the fall and store them in a cool, dry place over the winter.

Troubleshooting Gladiolus Problems

If your gladiolus are not blooming, it could be due to:

  • Planting the corms too shallowly or too deeply.
  • Not watering the plants enough.
  • Not fertilizing the plants regularly.
  • Planting the corms in soil that is too heavy or compacted.
  • Disease or pests.

If your gladiolus are wilting or yellowing, it could be due to:

  • Overwatering.
  • Too much fertilizer.
  • Disease or pests.


Gladiolus are beautiful and elegant flowers that can add a touch of beauty to any garden. With a little care, you can enjoy these flowers even in cold climates.

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