How to Start Gladiolus Bulbs Indoors

If you garden in a cold climate with a short growing season, you know the frustration of 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.

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 south-facing window or grow light and water.

If you prefer to watch rather than read, check out the videos below. Otherwise, keep reading for step-by-step instructions for starting Glads indoors and my 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 pointy side up 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 to 5 weeks before your final frost date.

For me in my Zone 3 garden in Saskatchewan, Canada, this means I’m starting them around the middle of April and planting them outdoors the third or fourth 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: 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. Anything you can do to help ensure your glads thrive in your short growing season, the better!

Don’t I Need Soil? AND what IF I LIVE IN A WARMER ZONE? DO I NEED TO START MY CORMS EARLY?

No and no! You can pot gladiolus bulbs up in soil if you like, but it’s not necessary. As long as you keep the roots moist, the corms will be fine.

As for starting them early, you can do this so you have successions of glads, but it’s completely up to you. It isn’t necessary to start glads earlier than I’ve described above. As long as you start them indoors, you will be most likely to see those beautiful blooms in your cold-climate garden!

And that’s it! A quick, simple hack to starting gladiolus bulbs indoors to ensure you get to see those beautiful blooms! I hope you feel inspired to try growing some gladiolus this spring.

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