Dahlias, cannas and gladiolus come up in Arkansas after a frost has blackened the foliage. At Little Rock, NOAA’s 1991-2020 Climate Normals put the first 32°F freeze between November 7 and November 20, and NWS Little Rock gives around October 31 for the first 36°F light frost. Tender bulbs take the earlier mark as their warning. Dig within a week or two of the blackening, dry them, and keep them cool until spring.
Do you have to dig them up in Arkansas?
It depends on whether the ground freezes where you garden. The USDA Plant Hardiness Zone Map (2023 edition) sorts every location by its average annual extreme minimum temperature. It places Arkansas between zone 6b and zone 8a. The line between “leave them” and “lift them” falls somewhere inside that spread. Where the soil freezes deep, all three must come out. Where it does not, they can stay under mulch.
Where can they stay in the ground?
Little Rock makes a useful reference. NOAA NCEI’s 1991-2020 Climate Normals give it an average daily low of 30.9°F in its coldest month. Nights hover right at freezing, but afternoons thaw the top of the soil, so the ground there seldom stays locked for long. In central and southern Arkansas, in a bed that drains well, a thick layer of shredded leaves or bark carries cannas through most winters. Gladiolus corms get a fair chance too.
Dahlias are the gamble. Their tubers rot in cold, saturated clay long before the cold itself reaches them, and Arkansas winters are often wet more than they are frozen. A cold snap deeper than the average also happens now and then. Anyone who paid good money for a named dahlia may reasonably decide the storage box is cheap insurance.
Where must they come up?
The Ozarks and the higher ground across northern Arkansas run colder than Little Rock, with harder and longer freezes. The zone 6b end of the state’s range sits there. Lift all three in those areas, every year. A bed that holds standing water in winter also rots tubers in the warm south, so it falls under the same rule.
Lift all three in northern Arkansas and in any bed that stays wet, and leave them under mulch only in well-drained soil in the milder central and southern parts of the state.
Your own yard may sit a half zone off the zone of the nearest town, because slopes, city heat and cold air pooling in low spots all shift it. The county extension office can tell you what winters have actually done to tender bulbs in your area. For bulbs that never need lifting, see Which Spring Bulbs Survive Your Winter.
When to lift them
The plant gives the signal. A frost that turns dahlia and canna foliage black and limp tells you the growing season is over, and that is when lifting starts. Gladiolus leaves often yellow and brown on their own before frost arrives, so they follow the same rule: wait until the top growth has clearly finished.
What dates should you plan around at Little Rock?
Two different frost thresholds matter here. NWS Little Rock gives around October 31 for the first fall frost at 36°F, the light-frost level. Tender plants are hurt at that threshold, so late October is when to start watching the forecast. A frost that actually blackens foliage is a 32°F freeze. NOAA NCEI’s 1991-2020 Climate Normals for the Little Rock station put the first one between November 7 and November 20, using the 30 to 70 percent probability band.
Plan the work for the stretch from around October 31 through the November 7 to November 20 freeze band, and dig within a week or two after frost has blackened the foliage.
Those are averages, and a given year can run earlier or later. The colder north and the Ozark highlands see these frosts sooner than Little Rock, so lifting moves earlier there. The southern part of the state gets them later. The leaves matter more than the calendar, because a mild fall can push the first blackening frost well past the averages. The First and Last Frost Dates in Arkansas list gives dates for other parts of the state.
Why does lifting too early cause rot in storage?
While the leaves are green, they keep feeding the underground parts. Dahlia tubers, canna rhizomes and gladiolus corms are still filling out and still thin-skinned. Once frost ends the top growth, they spend a short while firming up and setting their skins. Dig before that and the tissue is watery and soft, with fresh cut stems offering an open door to fungi. Those bulbs often look fine for a few weeks and then turn to mush in the box.
Waiting too long causes trouble of its own. A bed that stays cold and wet after the frost leaves tubers sitting in the worst conditions for them, which is why the window runs only a week or two. Dig on a dry day if you can. Push the fork in well out from the stem so the tines miss the tubers, and lift the clump gently. Dahlia necks snap easily, and a snapped neck is a bulb that will not grow.
Storing them over winter
All three need the same basic sequence. Cure them, clean off the soil lightly, then store them cool and dark with just enough moisture that they neither rot nor shrivel. The details differ by plant.
How do you cure and clean them?
Cut the stalks back to a short stub and shake off the loose soil. Do not wash dahlia tubers hard, because a rough scrub scrapes the skin and invites rot. Lay the clumps in a sheltered spot out of rain and direct sun, such as a covered porch or garage, until the surface is dry and the skins feel firm. That takes time. Gladiolus corms take longer, until the husks are papery and the old, shriveled corm underneath pulls away.
Sort as you go. Any tuber that is soft, spotted or cut deep should be discarded, because one bad piece can spoil the whole box. Label clumps by color or variety now. In April it will be impossible to tell them apart.
How do dahlias, cannas and gladiolus differ in storage?
The medium and the moisture level change from one to the next, as the table shows.
| Bulb | How to pack it | Moisture | What to watch for |
|---|---|---|---|
| Dahlia tubers | Boxes or crates in barely damp peat, vermiculite or wood shavings | Slightly moist | Wrinkling (too dry) or soft spots (too wet) |
| Canna rhizomes | Packed loosely in barely damp peat or sawdust, or wrapped in paper | Slightly moist | Rhizomes drying to leather; mold |
| Gladiolus corms | Mesh bags or open trays, with husks left on | Driest of the three | Mold; small shriveled corms |
Dahlias are the fussiest, since their thin tuber skins lose water quickly. Cannas have thicker rhizomes and take more neglect. Gladiolus corms want air and dry conditions, and a sealed damp box can ruin them.
A cool, dark spot that stays above freezing suits all three, such as an unheated basement or an insulated garage in the milder south. Avoid anywhere warm, because warmth wakes the buds early and wastes the stored energy.
The step that saves the most bulbs is simple. Check the stored bulbs from lifting until planting time, picking out any piece that has gone soft and misting lightly any that have begun to wrinkle. A little attention decides whether the box comes out in April full or half-empty. While you are tending the stored bulbs, fall is also the time to get hardy bulbs in the ground. Planting Spring Bulbs in Arkansas covers that timing.
What goes wrong
Rot shows up as soft, brown or black patches, sometimes with a sour smell or gray fuzz on the surface. It comes from storing bulbs wet, packing them in a sealed container with no air, or lifting them before the skin matured. Cure properly, use only barely damp packing material, and keep the box ventilated. Cut away a small spot and let the cut dry, but discard anything that is more than a small spot.
Shriveling looks like wrinkled, leathery skin, and the bulb feels light and hollow. The air or the packing was too dry, or the storage spot was too warm. Mist lightly, switch to a slightly damper medium, and move the box somewhere cooler. A moderately shriveled tuber often recovers. A hollow one will not.
Lifting early is the problem that does not show until later. The bulbs go into storage looking healthy, then turn soft in midwinter. The prevention is patience: wait until frost has blackened the foliage, and then dig within the week or two that follows. A bulb dug well ahead of that is unlikely to hold up all winter.
Leaving them in the ground one zone too far north is the costliest mistake, because it wipes out the whole planting. The giveaway comes in spring, when nothing emerges and the digging fork turns up gray mush. In the colder part of the Arkansas range, in the Ozarks and on high ground, lifting is the rule. Elsewhere, mulch only in well-drained soil. The Spring Bulbs section covers the hardy kinds that never need this fuss.
Common questions
Can cannas stay in the ground in Little Rock?
Often, yes. The average low in Little Rock’s coldest month is 30.9°F (NOAA NCEI 1991-2020), so deep ground freezes are uncommon. A thick mulch over well-drained soil carries cannas through most winters. A hard cold snap can still kill them, so gardeners who cannot afford a loss dig a few as backup.
Should I dig dahlias before frost to be safe?
No. Dahlias dug before the foliage has been hit by frost have not finished maturing and tend to rot in storage. If a light frost is forecast around October 31, a sheet or a frost blanket over the plants can buy time. Dig after frost has blackened the leaves.
When do I plant stored bulbs back out?
After the last spring frost has passed. NWS Little Rock gives around April 3 as the average last 36°F frost, which is the level that matters for tender plants. In northern Arkansas that date comes later, so plant later there. More timing for the state is in the Arkansas guides.
Is an unheated garage cold enough, or too cold?
An attached garage in central or southern Arkansas usually stays cool enough and above freezing. A detached garage or shed in the colder north can drop below freezing during a hard snap, which damages tubers. Keep a thermometer in the room for the first winter, and move the box inside the house if the reading gets close to freezing.