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Divine Dahlias: How to Grow These Garden Divas, From Seeds to Winter Storage

4 min read 7 Comments

Divine Dahlias: How to Grow These Garden Divas, From Seeds to Winter Storage

Ah, the show stopping, spotlight-stealing dahlia. These gorgeous blooms are so pretty and profuse that they have earned an unfair reputation as high-maintenance and hard-to-grow. Nothing could be further from the truth! Whether you grow them from seeds or tubers, dahlias are so simple to start, tend, and shelter over the winter. 


Dahlias might just be the world’s best cutting flower. How many other flowers can create the drama and impact of a full bouquet from just a couple of stems? Each dahlia blossom is a pyrotechnic pinwheel of petals, a spectacular starburst of color. And they are prolific bloomers, too! Once established, dahlias bloom for months without any fuss or bother.

We’re obsessed. And we know you are, too! While Pinetree Garden Seeds has long sold  a spectacular array of dahlia seeds, including individual AAS winners and brilliant mixes, we are so excited to be adding fresh tubers to our dahlia offerings in 2021 at our customers’ request. Before we start shipping our latest dahlia offering, we thought we would share a few tips and tricks to getting the most out of these gardening glories!


STARTING DAHLIAS FROM TUBERS

The easiest way to start dahlias is to sprout tubers in late spring that were gathered the previous fall. Pinetree Garden Seeds will start shipping dahlia tubers in mid to late March, in time for spring planting. So, what should you do when your tubers arrive?

If your soil has reached 60 degrees F, you can sow your tubers outdoors in your backyard garden about 18” to 2’ apart. If your soil is not yet that warm, you will want to start your tubers indoors in pots. Make sure the stem or sprout is facing up and cover your tuber with 2” of rich soil and plant out when conditions improve. 


STARTING DAHLIAS FROM SEEDS

Starting dahlias from seeds is no trickier than any other seedling. (And you only have to do it once! Taking dahlias up over the winter lets you start next year’s plants from tubers.) They are just a bit slower to germinate than other seeds you might have tried in the past—up to 21 days for some varieties. So don’t give up hope! They will be coming up in good time.

Dahlia seeds will do best if sown 6-10 weeks before the last frost in a seedling mix then transplanted to a rich potting soil and given steady light. Harden and transplant seedlings after the last frost and give them at least 18” to 24” of space. Most dahlias will grow to about two feet in height.


FOUR TIPS TO HELP YOUR DAHLIAS GROW

  1. Dahlias grow best when they receive a regular supply of water. Drip irrigation is the gold standard for dahlias but as long as you supply steady moisture, your dahlias will deliver. Like many plants, dahlias should be watered deeply from below to keep foliage dry and free of mold or blight.

  2. Use organic fertilizing and pest control methods. Dahlias are not susceptible to many garden pests, so they respond well to all-natural fertilization and pest prevention techniques. The one exception is snails and slugs, who do love tender young dahlia leaves. If you start seeing signs of a snail or slug attack, clear the ground around the plants of spent leaves and mulch these pests like to hide in and sprinkle the earth with natural slug and snail deterrents.

  3. When your dahlias have reached about a foot in height, pinch off the main stem to prompt the plant to put out more profuse growth and flower buds.

  4. If you are not cutting all of your dahlia stems, regular dead-heading of spent blooms will keep your dahlias in full flower for longer. You can pop off wilted blooms or you can take the time to prune back the stem, which will encourage longer stems for cutting and more new growth.

    If you intend to keep a particular dahlia plant in the garden solely for outdoor decoration, our gardening experts recommend snapping off the buds closest to the main stem. This encourages the plant to put out blooms around the perimeter, where they will be shown to best effect.

PROTECT YOUR DAHLIAS OVER THE WINTER
Regardless of your microclimate, dahlias keep dazzling late into the season, long after most other flowers have gone dormant. As they blaze out of early autumn beds it is time to begin thinking of how you can overwinter these floral wonders after the first killing frost.


In some growing zones 8 to 11, dahlias are considered winter-hardy perennials and you need only cut them back to a few inches above soil level for them to survive and begin regrowing in the spring. If you live in zones 2 through 7, however, your winter temperatures dip below 20 degrees F and your dahlias need more protection to power through to spring.


Taking up dahlia tubers is not a complicated process. This step-by-step guide from the Dahlia University shows you exactly how it should be done—with pictures! Once prepared and wrapped, dahlia tubers can be stored in a cool, dark, and dry place but should not be allowed to freeze. See how easy it is to tuck them in for spring?


Are you excited that Pinetree Garden Seeds is now offering dahlia tubers? Which varieties of dahlias are your personal favorites? Share your stories in the comments, reserve your dahlia seeds or tubers, and get ready for a dazzling dahlia season.

Dazzling Sun Dahlia

Paul Emory Dahlia

Creme de Cassis Dahlia Tuber





7 Responses

Priscilla Stanger
Priscilla Stanger

February 02, 2021

I love dahlias and was happy to read your advice on caring for them and getting longer stems. This will allow them to better fit into a cut vase. Thank you.

Beverly Kerry
Beverly Kerry

February 02, 2021

I’ve decided to give dahlias another try this year. I like the ones with big showy flowers.

Carol Blaser
Carol Blaser

February 02, 2021

I have grown dahlias for many years, but enjoyed starting plants from seed. I found both small ones and the larger mix you offer all getminatedquickly but got very large too early for me to plant out. Bring in more varieties. I had a bi-colored mix one year I just looked, but no idea of the variety name. It’s nice to not have all large/tall plants, I use lower varieties as a border for my perennials.

Jordan J Clarke
Jordan J Clarke

February 02, 2021

Dahlias are my favorite flower to grow. I am so excited that you are now carrying tubers. They really aren’t hard to grow so people shouldn’t shy away from puting these gorgeous beauties in their gardens.

NORMA Dean
NORMA Dean

February 02, 2021

I have always loved dalias the bloom so well and are so colorful.

Dolores Enriquez
Dolores Enriquez

February 02, 2021

I am very new to thos and did not even know you can start Dahlias with seeds. Now I want to give it a try!

THANK YOU
Dolores

Laura Oldenkamp
Laura Oldenkamp

February 02, 2021

That is really good information in the Dahlia University (American Dahlia Society) link that you provided. Additionally, I suggest joining a local dahlia society to get excellent advice, mentorship and opportunities for swapping in your region.

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