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Hamptons Life

Oct 22, 2018 10:55 AMPublication: The East Hampton Press & The Southampton Press

Dig And Store Dahlias, Caladiums, Cannas And More Tender Bulbs, Corms And Tubers

Healthy canna tubers nearly ready for storage. The stems need to cure a bit more and the rest of the soil needs to be cleaned off, but the tubers are plump and ready for several dark and cool months of storage.  ANDREW MESSINGER
Oct 22, 2018 11:23 AM

It’s just about time to get the tuberous dahlias, caladiums, cannas and other tender but storable goodies out of the ground. If you plan on saving these fleshy roots, corms and tubers for replanting next summer, there are a number of things to do now.

First off, plan on digging them sooner instead of later. It’s hard to do with the gorgeous dahlias, as they will bloom for several more weeks. But if you want to hold them over, compromise will be the rule. Be careful when digging so that you don’t damage the unseen goodies in the ground. And try to dig with foliage attached—this facilitates handling and later identification. Once dug, the soil should be completely shaken or washed off and the remaining plant put in a warm place to dry. Now dry does not mean wither. Mother Nature will wither the roots on her own between now and May. You want to be left with firm, plump tubers and roots. All, including bulbs like the Caladiums, Alocasias and Calocacias, should be free of mold, soft spots and rot.

Dahlias can be taken from the ground as soon as the foliage starts to blacken, but don’t wait until we have a heavy frost or freeze, as this may damage the plants. First, label the plant by variety or color. Next cut the stems off the plants so that when you’re done working them, two inches of stem remains. While digging, you can leave more stem for easier handling.

Next, use a spade or digging fork to dig around the plant, leaving plenty of room as the tubers may have grown quite a bit since they were planted. Once the clump is loosened, slide your digging tool under the clump to lift it. The tubers may be brittle, so a light touch is helpful.

In sandier soils, the soil will tend to drop off if it’s dry. But if not, put the clump on a sheet of plastic or in an open plastic container. Remove any soft or diseased portions. Some wash the tubers to remove all the soil, while some leave some dry soil on them. Leaving soil on can increase the chances of fungus problems during storage. The tubers shouldn’t be stored in wet soil, though, and they need to be exposed to air for several hours to let the stems cure or dry. Stem ends must be dry before storage.

The next step is to get the tubers (stems up) into an airy box (a wooden wine box), bushel basket or vented plastic crate. Lay the tubers onto some peat moss, vermiculite or sawdust and cover them but not so buried that the stems get covered.

Store them in a cool, dry spot between 40 and 50 degrees but check them in about a month and again in January for signs of shriveling or fungus. Don’t expect 100 percent of them to survive, especially if this is your first try. This seems to be both an art and science learned from failures and successes.

Cannas are dug and stored in a similar manner, but these tubers are much, much larger and require more storage space and a bit more care. The canna tubers are going to be fat and plump and they should be washed of all soil and allowed to thoroughly dry before being stored. Unlike the dahlias, the cannas should be harvested a bit earlier as they are very prone to rot after a frost. Once dug and gently cleaned, put them in a garage or warm place for a day or two—out of sunlight—and allow them to dry. Once dry, they can be packed into black plastic bags using peat moss under and around them. Don’t seal the bags or you’ll have nothing but mush in the spring. It’s even a good idea to use a knife and make a few slits on the sides of the bag for some air circulation. Store in a cool dark place at around 40 to 45 degrees.

Alocacia and Calocacia bulbs (elephant ears) are also tubers and are handled in pretty much the same way. Dig the roundish tubers before a hard frost or freeze, wash them, dry them and let them cure for a day. Then pack them the same way as noted for cannas. Keep in mind, though, that both of these plants’ leaves contain calcium oxalate or oxalic acid, and this can cause some skin irritation. Wearing latex or another type of disposable glove is advised. These can be stored at 40 to 45 degrees or slightly cooler.

Gladiola bulbs, which are technically called corms, can also be dug and stored then replanted next year. When frost kills the foliage, dig a circle or trench around the bulbs being careful not to damage the smaller bulbs, or cormels. Cormels can also be replanted, but they will take another two years (and re-digging) before they flower. Cut off the stems and shake off any soil, but don’t wash them. A soft brush can be used to remove the soil. You can save the larger corms (at least a half inch in diameter) for next year or go crazy and save them all.

Allow the corms to cure for two to three weeks out of sunlight at between 60 and 70 degrees. When cured, remove any remaining roots. Store the corms in labeled paper bags or layer them in a cardboard box with vermiculite or peat moss. Keep the corms cool, around 40 degrees and don’t seal them in containers and don’t allow them to freeze.

Not too many gardeners store their glads from year to year because the process is a bit tedious and few of us have the right storage conditions. They are also pretty inexpensive. But, it could be an interesting project.

Acidanthera is a fantastic summer bulb that makes wonderfully scented cut flowers. It’s not hardy, though, so if you grow it (if you don’t, you should) the bulbs (again, really corms) are lifted before any frost, cleaned and stored in peat moss or vermiculite at between 60 and 65 degrees. But, like the glads, these bulbs tend to be inexpensive and are easily purchased and planted every year. Years ago, we planted large blocks of them at staggered planting times for a long season of cuts. The following spring, we would see how they overwintered and simply bought new ones to fill in for those that were lost. There is always that secret satisfaction that gardeners get though being able to say you grow and replant your own

Caladiums, which may have cost you $10 to $30 in full foliage last June, can be stored, but they require different care. Since they are truly perennials in the tropics, they must go dormant and the bulb must be kept in a dark, but warm place. They can be packed just as described above, but keep them in a closet or some other place where the temperature will remain close to 50 degrees. You can begin to force them again in April or even March, but the soil temperature must be close to 70 degrees or you’ll end up with naught.

Lots of opportunity to keep busy here if you’ve got these plants and have the space and conditions to overwinter them. Just more opportunities to keep going then keep growing.

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