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Fall Home & Garden 2004: With proper care, dahlias can be saved for spring
Sunday, September 19, 2004

This is the first year I've fallen in love with dahlias. They've been grown in my garden before, but when the cold weather arrived, I would just let them freeze.

The dahlia, 'Zorro,' courtesy of Swan Island Dahlias.
Click photo for larger image.
I bought a bunch of tubers in the spring at the Greater Pittsburgh Dahlia Society's auction, and I'm so glad I did. Not only have I reveled in these new blooms, but their beauty forces me to save them for next spring's garden. And since I'm saving the dahlias over the winter, I might as well do the same for the other tender bulbs from the garden. Cannas and gladioluses are two examples I hope to save over the winter.

Everyone has a different way to keep them in storage. If they are too wet, they will rot; if too dry, they'll become unusable.

The process for dahlias involves drying and then curing. The goal is to get as many tubers through to spring.

Bill Kavchak, of the dahlia society, explained the process he uses:

Cut the dahlia down a couple of weeks before the last frost. The stalk is hollow, so it must be covered to avoid being soaked by fall rain. Some people use a stone, but Kavchaks uses aluminum foil. The tuber stays in the ground for a couple of weeks, still growing. This promotes eye formation. When the clump is dug and split, each division needs at least one eye to produce flowers the next year. Dig the tubers out, hose them off and let them dry for a couple of days in the shade on cardboard. Split them and mark every tuber with a magic marker. Kavchak actually marks the variety on the tuber itself.

Kavchak uses vermiculite as a storage medium. He starts with a five-gallon bucket of it and adds one cup of water. To tell if it's moist enough, grab a handful and squeeze. It will feel moist. To be sure that it's not too wet, shake your hand and the vermiculite should fall apart. He places the tubers in plastic grocery bags with the vermiculite. Each bag is tagged with the variety name. The bags are placed in cardboard boxes lined with newspaper. The boxes need to be stored in a cool frost-free place that ranges from 45 to 50 degrees. Check the tubers twice during the winter for rot. Pull any rotted tubers out and send them to the compost bin.

For other bulbs, use the same general process. Instead of cutting the glads or cannas, dig them out and use the same technique as for the dahlias.

Dahlias multiply each season, so next spring, offer your extras to friends. Then they will be hooked like the rest of us.

First published on September 19, 2004 at 12:00 am
Post-Gazette garden columnist Doug Oster can be reached at doster@post-gazette.com or 412-263-1484.