Digging and Storing Tender Bulbs: A Crop by Crop Guide
Dig dahlias, cannas, gladiolus, caladiums, elephant ears, calla lilies, and tuberous begonias within a few days of a killing frost, cure them, then store...
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tender bulbs dahlias cannas gladiolus overwintering storage
Digging and Storing Tender Bulbs: A Crop by Crop Guide
Dig most tender bulbs within a few days of a killing frost, shake off the soil, cure them somewhere warm and airy, then store them cool, dark, and dry. Gladiolus is the exception: lift it earlier, as its leaves yellow, and give the corms a long warm cure. Storage temperatures run from 35 to 45 F for gladiolus to 60 to 65 F for caladiums, so check the chart before you pick a shelf. Iowa State Extension sums up the goal well: dry enough to stay dormant, damp enough not to shrivel.
Already sorting out what stays and what goes? The Bulb Desk handles spring bulbs. This guide covers the tropical ones you have to lift.
Why the Timing Matters
Dig too early and the plant has not finished sending food down into the bulb. Wait too long and frozen soil or a hard freeze damages the bulb before you get it out. Illinois Extension says to dig within a few days of a frost, once the foliage has yellowed or been killed, so rot organisms do not get a chance to move in through the dying stems.
Dig several inches out from the plant, loosen the soil all the way around, then lift the whole clump with a fork. Cut or skinned bulbs are an open door for disease, so go slow. Shake off the loose soil. Iowa State says to rinse dahlia roots clean before curing; the rest can keep a little soil on them.
Label everything. A marker on the bulb or a tag on the bag saves you from a box of mystery roots in March.
The Short Version
| Crop | Dig when | Cure | Store at | Pack in |
|---|---|---|---|---|
| Canna | Cut to 4 to 6 in a few days after hard frost, then lift | 1 to 2 days | 40 to 50 F | Boxes, crates, or mesh bags, soil left on |
| Dahlia | Cut to 2 to 4 in several days after hard frost | About 1 day, until dry to the touch | 40 to 50 F | Vermiculite, peat, or wood shavings, clumps upside down; rinse soil off first |
| Gladiolus | Late summer to early fall, as leaves yellow | 2 to 3 weeks, warm and ventilated | 35 to 45 F | Mesh bags or nylon stockings, hung up |
| Caladium | When foliage droops and yellows, or after first hard frost | 1 to 2 weeks | 60 to 65 F | Dry peat moss or vermiculite |
| Elephant ear | After the first fall frost | 1 to 2 weeks | 55 to 60 F | Peat moss or wood shavings |
| Calla lily | After a killing frost | 1 to 2 weeks; Illinois says 2 to 3 weeks | 50 to 60 F | Peat moss or vermiculite |
| Tuberous begonia | Within a few days of a killing frost | 2 to 3 weeks | 40 to 50 F | Dry peat, vermiculite, or sawdust |
Sources: Iowa State University Extension for dig timing, curing, temperatures, and packing materials. Illinois Extension gives a slightly longer curing window for calla lilies, 2 to 3 weeks, so when in doubt give callas the extra week.
Signs to Dig, Crop by Crop
Canna. The tops collapse after a hard freeze. Wait a few days, then cut the stalks to 4 to 6 inches and lift the clump. Cannas are the easiest tender perennial to save and a good one to start with.
Dahlia. Blackened foliage after a hard frost is your cue. Wisconsin Extension notes you can also dig before a hard freeze once the tops die back from a light frost. Handle the tuberous roots gently, since they bruise.
Gladiolus. Leaves yellow and start to die back in late summer or early fall. This one is different from the rest: it gets a long, warm cure so the corms toughen up. Then snap off the old shriveled mother corm at the base and save only the plump new one.
Caladium. The leaves droop and fade as nights cool. Iowa State warns caladiums are the fussiest of the group and dry out easily in storage, so check them most often.
Elephant ear. Dig after the first fall frost and cut off the foliage. It stores a little warmer than most of the group, at 55 to 60 F, but caladium is still the warmest.
Calla lily. Dig after a killing frost and cut the foliage to 1 to 2 inches. Do not cut or nick the rhizomes.
Tuberous begonia. Dig within a few days of a killing frost, leave a little soil on, and cut the stems about 1 inch above the tuber.
How to Cure
Curing is just drying the outside enough that rot cannot get started. Illinois Extension puts the curing room at about 60 to 70 F, out of direct sunlight, with good airflow. Spread the bulbs in a single layer on newspaper or in a crate, not piled in a bucket.
Curing times vary a lot:
- Cannas and dahlias: 1 to 2 days
- Caladiums, elephant ears, calla lilies: 1 to 2 weeks
- Gladiolus and tuberous begonias: 2 to 3 weeks
How to Pack and Store
Use 2 to 3 inch layers of peat moss, sand, vermiculite, sawdust, or coconut coir in a ventilated container such as a cardboard box or milk crate (Illinois Extension). Keep bulbs from touching each other so one rotten bulb does not take out its neighbors. Never seal them in an airtight tub, which traps moisture and grows mold.
Gladiolus is the exception. It hangs in mesh bags or old nylons with no packing material at all.
Storage temperature is where most people get stuck. Normal house temperatures are too warm, and most garages swing below freezing in a cold snap. Iowa State notes that if you cannot find a spot in the right range, it is better to grow the plant as an annual than to watch it rot. A cool spare room, an unfinished basement away from the furnace, or a root cellar all work.
Checking Through Winter
Look in on the boxes every few weeks. Remove anything soft, moldy, or shriveled. If the packing material feels bone dry, mist it lightly. If it feels wet, take the bulbs out, air dry them for a few days, and repack in fresh dry material. Too much moisture causes more losses than too little.
Wait until spring to divide. Cutting the clumps in fall leaves wounds that rot during storage. In spring, cut so each piece has at least one or two buds.
Next Steps
- Find your storage spot now and put a thermometer in it for a week. If it holds 40 to 50 F, you are set for most crops.
- Gather boxes, packing material, and labels before the first frost.
- Dig cannas and dahlias a few days after their tops die.
- Lift gladiolus earlier, as soon as the leaves yellow.
- Bring tender herbs in too. See when to bring basil and tender herbs indoors.
Structured Data for the Pick a Plant Tool
Proposed shape for the tender bulb records. One record per crop, all temperatures in Fahrenheit.
``json { "tool": "pick-a-plant", "collection": "tender-bulbs", "updated": "2026-10-28", "records": [ { "crop": "Canna", "slug": "canna", "storageType": "rhizome", "digTiming": "A few days after a hard killing frost", "digCue": "Tops collapse after a hard freeze", "cutHeightIn": [4, 6], "cureDays": [1, 2], "cureTempF": [60, 70], "storageTempF": [40, 50], "storageMedium": "Cardboard box, crate, or mesh bag; leave a little soil on the rhizomes", "container": "ventilated", "checkIntervalWeeks": 3, "hardyZones": null, "difficulty": "easy", "source": "ISU" }, { "crop": "Dahlia", "slug": "dahlia", "storageType": "tuberous root", "digTiming": "Several days after a hard frost", "digCue": "Foliage blackened by frost", "cutHeightIn": [2, 4], "cureDays": [1, 1], "cureTempF": [60, 70], "storageTempF": [40, 50], "storageMedium": "Vermiculite, peat moss, or wood shavings; clumps upside down", "container": "ventilated", "checkIntervalWeeks": 4, "hardyZones": null, "difficulty": "easy", "source": "ISU" }, { "crop": "Gladiolus", "slug": "gladiolus", "storageType": "corm", "digTiming": "Late summer to early fall, as leaves yellow", "digCue": "Leaves yellow and begin to die back", "cutHeightIn": [1, 2], "cureDays": [14, 21], "cureTempF": [60, 70], "storageTempF": [35, 45], "storageMedium": "Mesh bag or old nylon, hung with no packing material", "container": "mesh", "checkIntervalWeeks": 4, "hardyZones": null, "difficulty": "easy", "source": "ISU" }, { "crop": "Caladium", "slug": "caladium", "storageType": "corm", "digTiming": "When foliage droops and yellows, or after the first hard frost", "digCue": "Leaves droop and fade as nights cool", "cutHeightIn": null, "cureDays": [7, 14], "cureTempF": [60, 70], "storageTempF": [60, 65], "storageMedium": "Dry peat moss or vermiculite", "container": "ventilated", "checkIntervalWeeks": 2, "hardyZones": null, "difficulty": "hard", "source": "ISU" }, { "crop": "Elephant ear", "slug": "elephant-ear", "storageType": "corm or tuber", "digTiming": "After the first fall frost", "digCue": "Foliage damaged by the first frost", "cutHeightIn": null, "cureDays": [7, 14], "cureTempF": [60, 70], "storageTempF": [55, 60], "storageMedium": "Peat moss or wood shavings", "container": "ventilated", "checkIntervalWeeks": 3, "hardyZones": null, "difficulty": "easy", "source": "ISU" }, { "crop": "Calla lily", "slug": "calla-lily", "storageType": "rhizome", "digTiming": "After a killing frost", "digCue": "Foliage killed by frost", "cutHeightIn": [1, 2], "cureDays": [7, 14], "cureTempF": [60, 70], "storageTempF": [50, 60], "storageMedium": "Peat moss or vermiculite", "container": "ventilated", "checkIntervalWeeks": 3, "hardyZones": null, "difficulty": "moderate", "source": "ISU" }, { "crop": "Tuberous begonia", "slug": "tuberous-begonia", "storageType": "tuber", "digTiming": "Within a few days of a killing frost", "digCue": "Foliage killed by frost", "cutHeightIn": [1, 1], "cureDays": [14, 21], "cureTempF": [60, 70], "storageTempF": [40, 50], "storageMedium": "Dry peat moss, vermiculite, or sawdust", "container": "ventilated", "checkIntervalWeeks": 4, "hardyZones": null, "difficulty": "moderate", "source": "ISU" } ] } ``
Notes for whoever wires this up:
cureTempFof 60 to 70 F comes from Illinois Extension, not Iowa State. Iowa State gives curing times per crop but not a room temperature.storageTempFranges are the Iowa State per-crop numbers. Do not average them into one range; the crops genuinely differ.checkIntervalWeeksis a practical suggestion, not a sourced number.difficultyis editorial, based on Iowa State calling cannas easy and caladiums difficult.- Filter idea: let people sort by storage temperature so they can group crops that share a shelf.
Sources
- Iowa State University Extension, How to Overwinter Tender Perennials: https://yardandgarden.extension.iastate.edu/how-to/how-overwinter-tender-perennials
- Iowa State University Extension, How do I overwinter gladiolus bulbs?: https://yardandgarden.extension.iastate.edu/faq/how-do-i-overwinter-gladiolus-bulbs
- University of Illinois Extension, Tips for overwintering tender bulbs: https://extension.illinois.edu/blogs/good-growing/2025-10-24-tips-overwintering-tender-bulbs
- University of Illinois Extension, Give summer-blooming bulbs a second chance: https://extension.illinois.edu/news-releases/give-summer-blooming-bulbs-second-chance-store-them-over-winter
- University of Wisconsin Madison Extension, Storing Tender Bulbs for Winter: https://hort.extension.wisc.edu/articles/storing-tender-bulbs-for-winter/