Moxie Gardener

Dahlias bloom from mid summer until killed by frost.

Dahlias are classified as summer blooming bulbs, but they’re grown from tubers, which are a thick bulbous root, like a potato.

Dahlias are native to Central America and were known to be used by the Aztecs. First sent to Europe in the late 1700’s, they were cross-bred and hybridized by botanists and plant lovers everywhere. By the end of the twentieth century there were nearly 50,000 named varieties.

Plant dahlia tubers in full sun. Plant four inches deep and mix compost into the soil when you bury them. Lay the tubers on their sides with the eyes facing upward.

Mulch with a three to four inch layer of compost, straw, or pine bark. Keep well watered; dahlias like to be moist, but not saturated.

Each tuber will produce many shoots. If you thin them to the strongest four shoots per tuber, the flowers will be bigger, bolder, and more eye-popping.

When the plants are about a foot tall with at least three pairs of leaves, pinch out the tip to encourage the plant to branch out and it will produce even more flowers.

Fertilize once when planting and then again six weeks later with a low nitrogen fertilizer.

Dahlias are only hardy to USDA Zone 8. In zones further north, dahlias must be dug before winter and stored in a frost free area.

After the tops are killed by frost, cut the stems to about two inches high. Dig the tubers with a garden fork. Begin digging a foot from the center of the plant so you don’t pierce the roots with the fork.

Gently remove the dirt from the tubers. Spread them out in a well-ventilated, shaded area to cure for a few days. Then pack each clump of tubers upside down in a well ventilated box or basket. Use slightly damp vermiculite or peat moss to cover the clumps.

Store the tubers at temperatures between 35 and 50 degrees F. Keep them away from drafts, very damp, or very dry conditions. If the roots look shriveled during winter, sprinkle a little water on them and repack.

Divide your dahlia tubers every spring to increase your collection. Cut the tubers so that each piece has at least one shoot growing. Plant these separately and they, too, will multiply.

Dahlias make stunning floral arrangements and they last for a long time as a cut flower.

This entry was posted on Friday, May 29th, 2009 at 5:55 PM and is filed under Flowers. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.