Regional Gardening Reports :: National Gardening Association

In the Garden:
Northern & Central Midwest
October, 2007
Regional Report

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Dahlia 'Gallery Art Deco' is the color of a sunset.

Winter Care for Those Beautiful Tender Bulbs

This is the first year I've grown dahlias, and I'm hooked. They gave me color the entire summer, both in the garden and for the kitchen table. I'm adding them to my list of tender bulbs to grow. The time is coming for our first frost, so it's necessary to refresh my memory on how to best take care of all tender bulbs.

Many summer-flowering bulbs, tubers, and tuberous roots are native to warmer climates, so in our area these bulbs must be stored in a frost-free area over the winter. Methods vary depending upon the species, but if properly done, the flowering beauty of the bulbs can be enjoyed year after year. Here are a few tips that will help your summer bulbs come through the winter ready to grow next spring.

Caladium. When the leaves of the plant start to droop in early fall, begin to withhold water to allow the plant to go dormant. Before the first frost dig the tubers. Remove any remaining leaves, soil, and old roots, and place the tubers on a shallow tray. Store in a dry, warm place at about 70 degrees F. Caladiums will survive at lower temperatures, but their vigor will be reduced the following season.

Calla lily. I grow calla lilies in a pot, and after they are finished I just bring the pot indoors to the basement, let the foliage and soil dry out, and don't give them a thought until they go outside in the spring.

Canna. When frost blackens the foliage, cut the stems back to 6 inches above the ground. Leave the tubers in the ground for a few days and then lift the clumps with a spading fork. Do not separate the clumps, and allow them to dry with some soil adhering to the roots. Dry the clumps in an airy room for a few days prior to storage. Then store the clumps upside down in a cool place (50 to 60 degrees F).

Dahlia. After frost has blackened the foliage, cut the stems to 6 inches above the ground. Leave the tubers in the ground for 7 to 10 days, then carefully dig and brush the soil from them. The clumps of tubers should be turned upside down and exposed to full sunlight for several hours to allow any sap or moisture to drain from the stalk. Store in a dry, frost-proof place (45 to 55 degrees F, 80 percent relative humidity) with a covering of dry vermiculite or peat moss to prevent additional moisture loss.

Gladiolus. Prepare glads for storage by cutting the leaf stalks at about 2 inches above the ground when foliage turns yellow (before the first frost). Lift the corms from the ground with a spading fork, taking care not to bruise them. Cure them in a tray in a dry, airy site for several weeks. After they're dry, separate the corms, remove the roots, and break away the old shriveled corms at the base of the new corms. Store in trays or shallow boxes in a cool place (between 40 and 45 degrees F, 80 percent relative humidity.)

Tuberous begonia. In fall when the foliage begins to yellow, gradually reduce water. Do not withhold it entirely. When the foliage dies, remove it and stop watering. If a portion of the main stem remains, do not forcibly remove it as this will damage the tuber. The stem will eventually fall off during the curing process.

Dig the tubers and carefully remove the soil, washing them if necessary. Spread them in flats and place them in the sun or any dry, well-ventilated area. It is essential that all excess moisture evaporate from the tubers. This should take about two weeks. Store in a single layer in shallow trays in a cool, dry place (45 to 50 degrees). Tubers may be either left uncovered or lightly covered with dry peat moss, vermiculite, or dry sand.

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