Q: I am new to dahlias and see their bulbs for sale in the nurseries now. What do I do to successfully plant them? —H. R. Westhampton

 

A: Perfect timing for this question, H.R. Often in April, we hyperfocus on the nagging mess that reveals itself in the garden with the receding snow and overlook the opportunity that awaits in the humble tubers and corms of summer bulbs. Now is a good time to purchase them for best selection. Planting happens after threat of frost is over. Dahlia blooms jazz up gardens right when they need it in those languid days of August until Fall frost, bringing the full spectrum of warm colors to complement the autumnal purple asters and yellow goldenrod.

Dahlias are a bit like chocolates in that it is hard to have just one. There are at least 42 species of dahlias, not including hybrids, and they come in many colors such as pink, white, red, yellow, orange and purple. They come in a variety of shapes, sizes, and heights, so be sure you research which type is most appropriate for your gardening plans. 

While often called bulbs, dahlias are actually “tubers”, like potatoes. The tuber is the flower’s food storage unit and the dahlia tuber looks a bit like a bunch of attached fingerling potatoes with roots. Each section has a growing point or “eye” from which a shoot will rise and become a stem. Do not break or cut the tuber.  

To plant the tuber, wait until the threat of frost is gone, then dig a hole 6 to 8 inches deep, loosen the soil around it adding some compost and organic fertilizer — always follow label instructions — then set the tuber in the hole with the growing points facing up, cover and gently tap down the soil, water and you are done. If you choose tall plants, remember to stake them. You can plant dahlias in pots during the next couple weeks to put outside post-frost.

In the fall, once the frost hits, they are done. As soon as this happens, dig up your dahlias, cut the stem a few inches above the tuber, wash off the dirt, and put them out in the sun to dry. Once dry, put them in a paper bag and surround them with peat moss or sawdust to help keep them dry. Store them in a cool, non-freezing place over winter until next spring. As I learned the first time I grew dahlias, if you leave them in the ground over winter, they turn to mush!

Along with asters, dahlias look beautiful mixed in with cheery annuals such as nasturtium and sunflowers or the tall, graceful lavender-flowered wands of Verbena bonariensis. They will also share the limelight with robust clump-forming perennials, such as salvia and artemisia, which behave themselves, stay put and will not pilfer dinner or drink from the thirsty, heavy-eating dahlias. 

Dahlias are timeless, worthy additions to your garden, H.R. Enjoy them! Thanks for asking a (local) master gardener.

Have a gardening dilemma? Please send questions, along with your name/initials and community, to the Western Massachusetts Master Gardener Association at AskAMasterGardener @wmmga.org. One question will be selected and answered per week. wmmga.org

]]>