Guys and Dahlias: Tips on Growing this Fabulous Flower from the Experts

Guys and Dahlias: Tips on Growing this Fabulous Flower from the Experts

Posted by Kerry Kelley on Aug 11th 2022

This spring, as I was posting to our Instagram account, I spied a photo so intriguingly beautiful I had to spend a few minutes really looking at it. That's kind of a rare thing these days, so I decided to find out a bit more about the creator. I discovered the lovely website of two cut flower growers from New Mexico, Steven and Kee-ju Hong-Elder, called "the kokoro garden." There they enthusiastically share their love of of all things floral through gorgeous photos, experienced advice, and unique arrangements. As explained on their site:

Kokoro (Japanese: ) means
"heart; mind; mentality; emotions; feelings"

In the context of the Kokoro Garden - it’s about a garden that makes you happy, that gives you emotions and makes you feel something. It’s also about gardening for yourself - the passion of being outside, growing things, trial and error of a garden and having your hands in the dirt.

That promise is delivered with sound advice on growing, designing and selling, in keeping with their minimalistic outlook. With their many guides to the culture of different flowers and plants, home gardeners will find plenty of useful information, as will those working in a more professional vein. Particularly striking are their creations centered on dahlias, a luscious blooming beauty that should be on your radar if you're looking for some big mid-summer through fall color impact or to add bold blooms to your cutting garden.

Kee-ju and Steven have grown dahlias (among many other flowers) for 10 years now, and currently devote over 1000 square feet of their farm to these fabulous flowers. Kee-ju is drawn to their radial symmetry, and the myriad forms, sizes, and colors. "You're never going to get bored with them," he declares.

His particular favorite, 'Cafe au Lait,' he credits as one of the reasons they started growing for cut flowers. "Although it can be fussy and isn't the most productive dahlia out there, when it does bloom it is absolutely spectacular in its color and form. Even people who aren't into gardening or flowers are mesmerized by Cafes, and they are always magical."

Each year, they winnow the possibilities to just a dozen varieties, focusing on vigor and productivity first, as they need heavy bloomers that will tolerate being frequently harvested. Color and form are the second set of criteria--Kee-ju has a personal preference for the warm end of the color spectrum, frequently working designs in vivid orange, glowing peach, and delicate cream hues. Aside from the artistic considerations this makes practical sense, as dahlias "bloom their beautiful heads off" until frost, and this palette is perfect for fall arrangements.

Choosing a color scheme surely helps pare down the choices-- there are well over 50,000 registered cultivars. Blooms are in one of 15 different forms (or more, depending on the reference), any color except for true blue (including bicolors, blends, and variegated), and sized between 2" and a whopping 10" for the largest "dinnerplate" types. Plants tend to be bushy, and size corresponds roughly to flower size--smaller blooming plants will be 12-20" tall, while dinnerplates can grow to 5-6 feet. Small to intermediate sizes can be successfully grown in containers.

Kee-ju highly recommends 'Terracotta' as a top choice for a large dinnerplate variety, remarking that "it's quite vigorous, especially for a dinnerplate dahlia. This variety just wants to grow and bloom!" Dinnerplates, with their enormous silky flowers, are truly dramatic and exciting in the garden or vase, and beg Kee-ju's question," What other flower gets to that scale and has such character?"

Among smaller flowering types, 'Cornel Bronze' is their "go-to variety for the ball shape," possessing "great form, vigor, and is an easy color to work with." 'Red Cornel' offers the same in a rich ruby shade. For loads of cut flowers, Kee-ju extolls the virtues of pompon varieties such as 'Ginger Willo.' They are "quite productive as far as the sheer number of blooms you can harvest."

Dahlias will perform best with 6-8 hours of full sun, and prefer a moist, well-drained soil. Kee-ju warns, "While they are a moisture-loving plant, you have the potential of rotting the tubers," if planted in a poorly drained spot. Since the kokoro garden's location receives a mere 11" of rain per year, they must rely on drip-irrigation. The upside of that is they report they have few issues with fungal diseases like powdery mildew, to which dahlias in more humid locations are prone. They do suggest that large broad-leaved varieties are usually more troublesome in this regard.

Kee-ju recommends a regular fertilizing regimen for best vigor. "We mix a slow-release organic fertilizer into our beds and containers and supplement once a month with an organic water soluble fertilizer to keep up with the plants." This is especially important in the cutting garden, where plants need to rejuvenate quickly after harvesting.

Most taller dahlias will require some type of support. For home growers, individually staking and tying, or using a wire plant support with a grid or peony hoop is sufficient. For Steven and Kee-ju this became "an impossible task," so now they "corral" the beds with tall sturdy stakes at the corners and jute twine encircled every 6 inches up to 2 feet high. For varieties that they know grow naturally taller, such as the very vigorous 'Tartan' and 'Totally Tangerine,' they will corral a bit higher.

Preemptive pruning also helps keep plants from becoming top-heavy. "We'll give our dahlias a pinch at the third node to encourage a more branching, compact form." Kee-ju further advises, "Harvest deep into the plant when cutting....as this has the additional benefit of encouraging more long stems and a greater number of blooms." Repeating this strategy and deadheading unusable blooms throughout the season keeps the plants in shape.

Although dahlias can be grown from seed, by far the most common (and simplest) way is by planting the tubers they form. "Dahlias are actually great for gardeners to grow because they are much less finicky than starting a plant from seed," Kee-ju encourages. "You just plant the tuber and watch it grow!"

I haven't grown dahlias myself for many years (note to self: grow dahlias again!), but I can attest to their ease of growth. Kee-ju does not exaggerate. The biggest issue for some will be their hardiness--as a tender perennial they can only be safely overwintered up to zone 8. In those zones, just cut the stems down after frost and mulch for winter. Zone 7 is an intermediate zone where dahlias may return if mulched heavily, depending on winter temperatures and the amount of snow cover. Snow acts as an insulator, so the tubers fare better with that warm white blanket in a cold winter.

Colder zones will definitely need to lift the tubers and store for winter. Fortunately, this is not a difficult task. The leaves will die back, usually after the first hard frost. Simply cut the stems to about 3 inches, and with a garden fork, carefully lift the clump of tubers from the soil. Shake off as much soil as possible and allow to dry for a few hours before storing.

Store as you would any other tuber--like a potato, for instance. Place in a paper bag (no plastic!) with a bit of moist peat moss, vermiculite, or sawdust in a cool (40-50 degrees), dark spot, and check to see that they are not completely drying out (shriveling) over winter. Should that be the case, slightly dampen the packing material so that they will re-plump. Storing too wet will rot the tubers.

In more northerly zones where the growing season is shorter, you can start your tubers in pots in early spring, in a sunny window or under a plant light. Neither the plants nor the tubers should be planted out until there is no danger of frost, unless you are able to cover them as needed.

Despite the kokoro gardens' dry, mild 7B climate, Kee-ju says they do still lift their dahlias from the growing beds. (It's a big investment, after all). As only the top 3 inches or so of their ground freezes, they re-bury them 8-12" deep in a large trench in a more sheltered location, covering them with soil, mulch, and finally a tarp to keep them dry. "It's really cool because the tubers never really dry out or go dormant--they are just hanging out in suspended animation and in some cases the stems cut back to the tuber are still green!"

Kee-ju advises that overwintered tubers must be divided in spring before replanting. Without intervention, they will form "huge tangled clumps" with healthy tubers interspersed with dead and rotting bits, resulting in poor growth. "It's actually best for dahlias if you don't give them a lot of tuber to work with. A dahlia society member recommended that if you have a huge mother tuber to actually cut off half to encourage the dahlia to grow and put out more tubers later on," he explains.

When it comes to designing, Kee-ju finds the ball and waterlily forms the easiest to use. He enjoys pairing them with their other summer flowers (celosia, zinnias, cosmos, gladiolas, for instance), and recommends foliage accents of summer grasses and herbs like basil and scented geranium. Creamy Cafe-au-Lait dahlias with purple 'Dark Opal' basil is a favorite combination.

"The dinnerplates are hardest to work with because of their sheer size," Kee-ju warns. "I used to jam (them) into mason jar arrangements--they looked absolutely ridiculous because they took up the entire jar," he willingly admits. "It's important to match your vessels to the size and scale of your bloom." These days, those impressive blooms are reserved for large centerpieces and bridal bouquets. He also mentions that dinnerplates have a shorter vase life than other varieties.

In the vase, Kee-ju has found that dahlias with more petals or a more double form last longer, while single-flowering types fare less well, some lasting less than 48 hours. "Pompoms and ball forms can last up to a week if kept in a cool environment with clean water," he says.

If restricted to growing only one dahlia , Kee-ju would choose 'Cafe au Lait,' despite its aforementioned drawbacks. But he admits a special fondness for the pompom and ball forms. "They are so cute and perfect, and I find them to be so visually intriguing in their spherical form. A perfect sphere of tightly overlapped petals is just so unique, and so much fun to look at. And the fact that they are so rare with many old varieties having become unavailable makes them that much more special to me as well."

"That being said," he confesses, "I can't say no to any form of dahlia--we grow all the forms and appreciate them all. It's no wonder that people have been so intrigued and entranced by dahlias and their capability to be bred into so many different and unusual forms."

Well-said, Kee-ju. We heartily agree!