Gardening: Dahlias are flower darlings

Nancy Szerlag
Special to The Detroit News

The cover of my October issue of Fine Gardening magazine features a gorgeous stand of dahlias promoting an article about these fabulous flowers by Nicholas Gitts, owner of Swan Island Dahlias mail order house ( Along with some great growing tips I’m sharing with you here, the article has photos of half a dozen specimens you won’t find in your local garden center. 

Swan Island is now taking orders for next spring and there are more than 300 varieties to choose from. Happy shopping. 

Dahlias are sun lovers and need a minimum of 6 hours a day. They thrive in soil that is enriched compost and drains well. 


Most dahlias are grown from tubers that range in size of a AA battery to several inches in length and can be long and skinny or short and fat. The good news is no matter the size, all are planted in the same manner which makes how-to a snap. You simply dig a hole 4 to 6 inches deep and lay the tuber on its side at the bottom and cover it up.  DO NOT water after planting or add fertilizer to the hole.  Once the shoots emerge, they will need watering in hot dry weather. Deep watering once or twice a week is best.

For the long vase life, the blooms are best cut when they are two thirds open, just when the sun comes up. Believe it or not plunging the stems in 2 to 3 inches of very hot water (160 to 180 degrees ) for an hour will extend their vase life. According to folks at Three Acre Farm ( in Byron Center, Michigan,  this trick will also revive a flower stem that wilts shortly after its cut.

Varieties that get more than 3 feet in height should be staked and this is best done at planting time. 

Dahlias are heavy feeders and should be fertilized with a low nitrogen fertilizer 30 days after planting and every three weeks their after.

Dahlia tubers are tender, so if you decide you want to overwinter them, wait until the frost hits them and then dig them up. You can store them in boxes or heavy-duty paper bags filled with sphagnum peat moss in a cool place (40 to 50 degrees) over the winter. Others just chuck them into the compost pile and purchase new ones in spring. 

If you belong to a garden club or have friends who grow dahlias and choose not to overwinter them, they probably would be more than happy to let you dig them

Nancy Szerlag is a master gardener and Metro Detroit freelance writer. Her column appears Fridays in Homestyle. E-mail her at , Ask Nancy. You can also read her previous columns at