To dig or not to dig

With each season comes changes in our plants. In the case of dahlias and glads — or gladioli or gladioluses or gladiolas, whichever name you use — fall is also decision time of "to dig or not to dig."

Let's consider dahlias first. In the Rogue Valley, leaving dahlia tubers in the ground is always a gamble. On the other hand, it's easier and less time-consuming. The two things dahlias won't survive are freezing and being in wet soil all winter. We can't predict our winter weather, but you do know what kind of soil you have.

I used to leave my dahlias in the ground, but a few years ago we had a spell of such cold weather that the ground froze, and I lost all of my dahlias.

Now I dig them each year. Lesson learned.

One bit of advice, however: Do not dig the dahlias too early. If you do they will be "green," meaning they have not had time to harden off and prepare themselves for winter, so they may not survive storage. Wait until two weeks after a killing frost to dig them. If we haven't had a killing frost by mid-November, it would probably be safe to dig them then.

Carefully dig with a spading fork and cut off all but a few inches of the stem. Let them dry enough to get most of the dirt off.

At this point, I like to label my dahlias directly on the tuber, writing the name or color with a felt-tip paint pen purchased at a craft or art store.

It's easier to divide dahlias in the spring, when you can see the buds and sprouts more easily, so I store the entire clump in dampened — not wet — sand or peat moss in the garage or shed.

If you choose to leave the tubers in the ground, cut the stalks to nearly ground level and lay plastic over them to keep rain out of the hollow stems. Then cover with straw, hay, mulch, leaves or even soil to give them a "security blanket" for the winter.

For gladiolas, wait until after a hard frost before you dig the corms. After loosening the soil around the plant, gently pull it up, and you will see several baby cormels, or cormlettes, along with the main corm. Shake the soil from the roots and cut off all but 2 or 3 inches of leaves. Label the leaf stubs with a paint pen and let the corms dry for a couple of weeks with good air circulation, such as on an old screen.

After a couple of weeks, you will see the old, shriveled corm. Separate it from the new corm and discard. Save as many cormels as you wish, realizing that they may not bloom the first year, but are a way to build your stock. As you sort the corms, bear in mind that this is a case where bigger is better when it comes to producing blooms.

Store the corms in paper bags, onion sacks or old pantyhose. Hang them in a cool, dark, airy place for the winter. Keeping the corms just above freezing will help kill thrips, which is the major insect problem of glads.

Carol Oneal is a past president of the OSU Jackson County Master Gardeners Association. E-mail her at

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