How to over-winter gladiolus

This month, I’ve learned you can’t do everything. Setting priorities means doing what counts most (such as saving the Gladiolus corms that have given me such pleasure), and setting the rest aside (such as NaBloPoMo 2017).

Before the unseasonal cold snap this month, I dug up the corms above. What’s a corm? It’s the thickened stem that is the “bulb” for plants like glads and crocuses. They store energy so the plant has something to nosh on next spring, in the same way that true bulbs (such as onion and tulip bulbs) do.

Until my “what the heck” experience with glads a couple of years ago, I never understood how easy (aka Helen-proof) glads are to overwinter. Typical advice is to dig the bulbs after frost kills the foliage. But I knew that this severe turn in the weather might be too cold. So I simply dug them up and brought them inside to cure, letting the skin dry for storage. Last year, as the weather cooperated I let them cure for a few days outdoors.

Here’s what to do next.

See see the double-decker effect in this fresh-dug gladiolus corm? The old corm is the brown bump at the top (the bottom of the actual corm). The white bump is the new corm the plant has created for next year. Peeping out between, you might just be able to see some baby cormels. More on those later.
Cut back the leaves and stems to about 10 cm/4″. As they were indoors, I used an old Christmas tree tray to reduce the mess. After a few days of drying, you should be able to gently pry off the old corms. I’m holding a couple here. Don’t force them. If they seem very reluctant, wait a day or two more. See how skinny they are? They used up all their stored food to feed this year’s flowers and growth.
The corms don’t shrink in width or diameter. The quarter-sized corm on the left produced an impressive bulb this year, as well as quite a few cormels. They must have been happy!
This is a gladiolus corm ready for storage. See how drying has allowed it to develop a protective skin? I trimmed the old roots and, a few days after removing the old corms, was able to snap off the stems. Again, don’t force it – it should come off with just a slight amount of pressure.
The bottom of my drying tray left me with dozens of baby cormels. These won’t produce flowers if you plant them next year. However, you can fatten them up next summer and try them the year after – if you have room. I’ll try saving some and decide later.
If some stems are stubborn, just cut them back to about 2.5 cm/1″ and store them that way. Toss any corms that are damaged or squishy. I put everything into a mesh bag from my bulbs, or an onion bag will do, and keep them in a cool, dark, well-ventilated place indoors (our spare bedroom!).

Call this my “what the heck” method! It has worked for me two years running. Give it a try!

1 comment

  1. Wow Helen – thank you !!!! Someone whose parents had moved had permission from the new owners to dig up plants from the huge, much-loved gardens, and was kind enough to let me dig up numerous gadiolus! I had no clue what to do next, and when I looked online I read about letting the glads sit in 80 degree temps for a couple of weeks! Not happening in the Toronto area!

    I absolutely love your easy-to-understand instructions and the accompanying photos. I was feeling pretty overwhelmed and now I feel totally relaxed about it. AND, I’ve found your blog, which I’m so excited about. 🙂 Next I’m going to look up peonies, which my friend also bestowed upon me.

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