How to Start Gladiolus Bulbs Indoors | Shifting Roots

How to Start Gladiolus Bulbs Indoors

If you live in a climate with a short growing season, you know the frustration with growing late season flowers, like glads. They take so long to bloom, that you run the risk of not even seeing your blooms if an early frost happens. And glads are so frost tender, that they’ll be instantly ruined.

A progression of 6 gladiolus corms, from simple corm, to various root growth, to leaf growth, to ready to plant glad.

After a few years of getting cheated out of my gladiolus blooms, I started forcing my gladiolus corms early indoors–almost guaranteeing that I would get to enjoy my flowers in bloom. The process is super simple. All you need are some corms, a window or grow light, and water.

If you prefer to learn in video format, watch this video below. Otherwise, scroll on for the instructions and answers to common questions.

Step by Step Instructions for Starting Gladiolus Corms Indoors

  1. Find a shallow container for the corms to sit in, like a tray, pie plate, etc.
  2. Place corms in a single layer in the container.
  3. Fill with water until it reaches about a third of the way up the corm
  4. Place near a south facing window or underneath a grow light.
  5. Refill the water to the same level as needed. Don’t let the roots that grow dry out.
  6. Once all risk of frost has passed, harden off the glads.
  7. Plant the gladiolus corms outdoors in holes 4 inches deep.

When do Gladiolus Corms Need to Be Started?

Typically, you should start the corms around 4-5 weeks before your final frost date. For me in my zone 3 garden in Saskatoon, SK, Canada, this means I’m starting them around the middle of April, and planting them outdoors the 3rd or 4th week of May.

Do Gladiolus Corms Need to Be Soaked Before Planting?

Technically no. You could skip this process altogether and just plant your corms outdoors after the risk of frost has passed. However, you run into the problem mentioned above that you might not get to see your blooms. If you choose to soak them, but don’t want to start them so early, it would likely still give your glads a little head start.

Don’t You Need Soil?

No. You can pot them up in soil if you like, but it’s not necessary. As long as you keep the roots moist, the corm will be fine.

Do I need to Start My Corms Early if I Live in a Warmer Zone?

No. You can start some of them early so you have successions of glads, but it’s up to you.

I hope you feel inspired to try growing some ranunculus this spring! If you need more help with your cut flower garden and putting everything together, you’ll love Cut Flowers Made Simple.

It’s the cheapest and easiest way to start a cut flower garden in your backyard, or use it as a way to dip your toes into flower farming.

Learn more here.

And if you’ve read this far, and you’re thinking that you need a more complete solution that will take you from seed starting to seed saving, you’ll want to check out the Ultimate Cut Flower Bundle instead.

Kristen Raney

Kristen Raney

Kristen is a former farm kid turned urban gardener who owns the popular gardening website, Shifting Roots.  She is obsessed with growing flowers and pushing the limits of what can be grown in her zone 3b garden.  She also loves to grow tomatoes, but oddly enough, dislikes eating them raw.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Grow roots with us



Hi, I'm Kristen and I help new gardeners learn to grow their own vegetables and beautify their yards. I also share recipes that use all that delicious garden produce. Grab a coffee (and your gardening gloves) and join me for gardening tips, simple recipes, and the occasional DIY, all from the lovely city of Saskatoon, Saskatchewan.

P.S. First time gardener? You'll want to download the quick start gardening guide below!