Storing Tender Summer Bulbs 

October 5, 2021 Jennifer Miller , Horticulture Coordinator

Summer bulbs excite me the way that plastic eggs from a giant rabbit vending machine did when I was a child. I get a thrill from anticipating what’s inside— no matter how many times I’ve seen it before. 

Perhaps that’s why I treasure saving bulbs from year to year, knowing that, come summer, I’ll relive the wonder of seeing them periscope out of the ground and unfurl their blooms in shapes as varied as funnels and pompoms.

Gladiolus Jester

'Gladiolus' Jester in the beds by the Fountain Beds.

Of course, not all bulbs need to be saved indoors. Those that are hardy in our climate happily winter over in the ground. The bulbs that have to be stored indoors originate from tropical climes and they would literally turn to mush if left outside in winter.

The list of tender bulbs is long and varied — from Mexican shellflower to pineapple lily. But not all tender bulbs are easy to store, and since we all have limits on time and space, it’s good to narrow the list to a few favorites that aren’t tricky to save.

Four bulbs I store without fail are dahlia tubers, canna rhizomes, gladiolus corms and giant chincherinchee bulbs. These are some of the most thrilling bulbs to see in displays and some of the easiest to store.

Dahlia Lindas Baby

Dahlia 'Linda's Baby'

Dahlias are the divas of the summer bulbs and have a reputation for being difficult to store, but in truth they aren’t as finicky as you might expect. If you follow these guidelines, you’re sure to have more than enough tubers come spring. 

  • Wait for two hard frosts before you dig out the tubers. After the first frost blackens leaves, cut the stems back to 6 inches. Then after the next freeze, carefully dig out tubers with a shovel.
  • Once lifted, rinse off your tuber clumps and let them dry for 24 hours. (But never on a concrete surface as this will pull moisture out of them too quickly.) 
  • Then clip off any hairlike roots and cut back stems to an inch. 
  • At this point you can separate tubers or store whole clumps in large plastic bins filled with wood shavings, taking care not to let clumps touch.
  • Store the bins in a dark place that stays at 40-50 degrees F and lay lids on top of bins but don’t seal them.
  • Check on the tubers monthly. Discard any tubers that become moldy. If mold occurs, replace the wood shavings.

The last three bulbs are the easiest to store.

  • Before digging up canna, gladiolus or giant chincherinchee in fall, let the foliage blacken.
  • Ease the bulbs out with a shovel, rinse off the dirt and cut back canna foliage to 6 inches, and gladiolus and chincherinchee foliage to 1-2 inches.
  • Lay out the bulbs to dry for 2-3 weeks, then remove the shriveled mother corms from gladiolus.
  • Store gladiolus and chincherinchee bulbs in open crates or mesh bags and canna in plastic bins between wood shavings. All three should be stored in the same conditions as the dahlias.

Dahlia tubers

Clump of dahlia tubers after it was dug up and rinsed.

This article appears in the October 2021 issue of Life on Capitol Hill.


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