Dig them up. Across Kansas, dahlia tubers, canna rhizomes and gladiolus corms should come out of the ground in the weeks after the first frost that blackens the foliage. At Wichita that falls roughly between the end of October and mid-November. Gardens farther north, in the suburbs or at higher elevation, usually get there sooner. Lift on a dry day, cure the roots, and store them cool and dark. Most failures trace back to digging too early or storing them too wet.
Do you have to dig them up in Kansas?
For most Kansas gardens, dig dahlias, cannas and gladiolus every fall rather than gambling on mulch. The USDA Plant Hardiness Zone Map 2023 places the state in zones 5b to 7a, a wide spread. The USDA system rests on a single variable, the average annual extreme minimum temperature, so it says how cold the worst night usually gets and nothing about how long the cold lasts.
Wichita’s numbers show how long. NOAA’s 1991-2020 Climate Normals put the mean daily minimum of the coldest month at 22.5°F at the Wichita station. That is the average night in the coldest month, not a record low. Nights that routinely sit about ten degrees under freezing for weeks push frost well into the soil, and a dahlia tuber or gladiolus corm sitting a few inches down has nothing to buffer it. These plants come from warm climates. Once the tissue freezes, it turns to mush by spring.
Where the line falls inside the state
Wichita is one reference point, not the whole state. The colder north and the higher ground in the west run colder than the airport, with a first fall frost that arrives earlier and soil that freezes sooner. In those areas there is no debate: everything comes up. At the milder southern edge of the 5b-7a range, winters ease and some gardeners leave cannas under a thick blanket of mulch. That works in some years and fails in others. A single hard stretch of cold can wipe out a whole planting, and cannas are cheap enough that people keep trying. I would not bet dahlias or gladiolus on it anywhere in the state.
A tuber that stays in cold, wet ground also faces rot, not just freezing. Heavy clay soil, common across much of eastern Kansas, holds water through winter and spring thaws, and sodden tubers rot even when the temperature never dips low enough to kill them outright.
If you are unsure how your own zone fits, Which Spring Bulbs Survive Your Winter walks through hardiness in more detail. Tulips and daffodils, covered under Spring Bulbs, are a different story. They need the cold and stay in the ground. Summer bloomers like these three are the ones that must come in. More local timing advice is collected in the Kansas guides.
When to lift them
The signal is a frost that blackens the foliage. Not a light dusting that nips the leaf tips, but the kind of freeze that leaves dahlia leaves limp, dark and wilted overnight. At that point the top growth is done, and the plant has finished sending energy down to the roots.
The window, counted from the first frost
NOAA’s 1991-2020 Climate Normals for the Wichita airport station show the first fall 32°F freeze arriving between October 23 and November 2. That range is the band where the odds of a freeze have climbed to between 30 and 70 percent. Source: NOAA NCEI 1991-2020 Climate Normals. Lift about one to two weeks after the killing frost, which puts the job at roughly the end of October through mid-November in Wichita. Some years the frost comes earlier and some years later, so let the plants set the date and use the calendar only as a guide.
Those are airport figures. Suburban and rural gardens typically see the first fall frost one to two weeks earlier than the airport, and more at elevation. If you garden north of Wichita, or on higher ground, shift the whole window earlier, and check your own county’s frost dates before you mark the calendar. First and Last Frost Dates in Kansas has the details.
Gladiolus follow a slightly different cue. Their foliage yellows and browns as the corms finish ripening, and in many Kansas gardens that happens around the same time the first frosts arrive. Once the leaves have faded, the corms can come up without waiting for a hard freeze.
Why lifting earlier backfires
Gardeners get nervous when the forecast turns cold and haul everything out in mid-October while the leaves are still green. Resist that. During the weeks after the foliage dies back, the root system finishes maturing, the skin toughens and the plant seals itself against moisture loss. Tubers pulled too early have thin skins and soft, high-moisture tissue. In storage they shrivel or, more often, turn slimy, because decay organisms get in through skin that never hardened.
Waiting too long has its own risks. Soil that freezes solid makes digging brutal and splits tubers when a fork goes in. A wet spell followed by a freeze can leave tubers sitting in cold mud. Aim for the stretch after the blackening frost and before the ground turns hard. When the soil is dry enough to crumble off the roots, that is the day.
For digging, start well out from the stem, loosen a wide circle with a garden fork, and lift the whole clump with soil attached. Dahlia necks snap easily, and a broken neck means that tuber will not sprout in spring. Cut stalks back to a short stub first. It also gives you a handle.
Storing them over winter
Storing all three comes down to the same sequence: cure, clean lightly, then keep them cool, dark and slightly moist so they neither rot nor shrivel. The details vary by plant, and getting them wrong accounts for most of the losses.
Curing and cleaning
Curing means letting the surface dry in a sheltered spot with air moving around it, such as a garage, porch or shed, out of the rain and away from freezing temperatures. Dahlias and cannas need only long enough for the skin to feel dry, not for the whole root to dry out. Gladiolus corms take longer, until the husks feel papery and the old shriveled corm pulls away from the fresh one on top.
Clean by shaking and brushing off loose soil. Resist the urge to scrub or wash tubers thoroughly, since lingering water invites rot and tiny wounds from a brush give fungi a foothold. If a section looks soft or has a dark spot, cut it out with a clean blade and let the cut surface dry before packing.
How the three differ
Here is how the three compare, using the same criteria:
| Plant | What you store | Packing | Main risk |
|---|---|---|---|
| Dahlia | Clump of tubers with a stem stub | Lightly moist medium such as peat moss, vermiculite or wood shavings, in a box or crate | Shriveling if too dry, rot if too wet |
| Canna | Thick rhizome clumps with soil shaken off | Lightly moist medium, never bone dry | Drying out completely, or mold in sealed containers |
| Gladiolus | Cleaned corms with old corm and husks removed | Dry, in a mesh bag or paper sack with air circulation | Mold and rot if kept damp |
Dahlias are the fussiest. Their tubers lose moisture quickly through thin skins, so a slightly damp packing material is what keeps them plump through winter. Cannas tolerate a little more variation but dislike drying out entirely. Gladiolus are the odd one out: corms store dry, like onions, and packing them in damp medium is a fast way to a bag of mold.
All three want a spot that stays cool and dark and does not drop to freezing. An unheated basement, an insulated garage or an interior closet against an outside wall can work. Heated rooms are too warm and dry, and tubers may sprout early or wither. A spot that freezes undoes all the digging you just did.
The monthly check
Here is the step that saves them: check the stored tubers once a month through winter. Open the boxes and look. Wrinkled, shrunken tubers need a light misting of the packing material. Soft, dark or smelly ones need to come out before they spread trouble to their neighbors. A forgotten box can lose half its contents by February, while a five-minute check catches most problems while they are still small. Keep the same routine until the weather warms and it is time to plant after the last spring frost.
What goes wrong
Four problems account for nearly every failure, and each leaves a recognizable sign.
Rot is the most common. Tubers turn soft, dark and sometimes slimy, and the box gives off a sour smell. It usually comes from storing them too wet, packing them in sealed plastic, or lifting before the skin hardened. Prevention means a proper cure, lightly damp rather than wet packing, and a container that breathes. Cut away small soft spots early and let the cuts dry.
Shriveling is the opposite problem. Dahlia tubers wrinkle like old fruit and may never sprout. The cause is storage that is too dry or too warm, often a heated basement or a loose paper bag. A little extra moisture in the packing and a cooler location usually stop it, and tubers caught before they are fully collapsed often recover.
Lifting too early gives you both of the above, because tubers that did not finish maturing have thin skins and lose water or rot. The fix is patience. Lift in the window after the first blackening frost, not before. That means waiting even when the garden looks tired in early fall.
Finally, there is leaving tubers in the ground one zone too far north. Gardeners in the colder parts of Kansas sometimes copy advice written for milder regions, or read of a neighbor whose cannas survived, and skip the dig. One winter of deep frost ends the experiment. If you try it anyway, treat it as a trial with a few extras and keep spare stock indoors. Come spring, Planting Spring Bulbs in Kansas covers soil and timing basics that carry over to getting stored roots back in the ground.
Common questions
Can I leave cannas in the ground in Kansas?
In the colder north and higher ground, no. Farther south, where winters are milder, a thick layer of mulch sometimes carries them through, but it is a gamble. Lifting the rhizomes costs an hour and protects the investment.
What if the ground freezes before I get to them?
Dig anyway once the soil thaws enough to work, taking care not to split the clumps. Tubers in frozen soil may already be damaged, so inspect them closely. Firm ones are worth storing, and soft or translucent ones should go in the compost.
Do I have to wash dahlia tubers before storing?
No, and heavy washing can hurt. Let the soil dry, brush it off gently, and keep the tubers as dry on the surface as you can. A light rinse is fine only if you let them dry completely before packing.
When do stored tubers go back in the ground?
After the last spring frost, once the soil has warmed. Dahlias and cannas planted into cold, wet soil tend to rot before they sprout. Last frost dates also run later in the colder north, so check the local numbers rather than going by the calendar.