Dahlias, Dahlias, Dahlias

Part I

About:   If you are looking for a bodaciously beautiful flower to grow, look no further than to dahlias.  Their form can be a large dinner plate, double decorative shape, quilled, ball shaped, tiny pom pom, and simple collarette which resembles an open anemone.  In the same manner that there are multiple shapes, there are multiple variations in color.  Almost all colors except blue can be found, and even a very dark maroon variety as Black Satin, can be close to black.  Common colors are yellow, white, cream, red, pink, purple, lavender, salmon, orange, with multiple variations in between to stripped, tipped, and spotted with color, or with central coloration of white yellow, and orange.  It is difficult not to fall in love with dahlias, as one variety is more beautiful than the next.  I challenge you to choose just one when looking through a catalogue…it is impossible!  One particularly large flower, a dinner plate variety (usually about 8 inches in diameter or larger) is Cafe au Lait or translated from the French, coffee with milk.  It is popular for wedding work, and can range from a pale pink to darker pink, to a beigy pink.  Sometimes you can see all three variations on a single plant blooming at the same time!  That brings up the point that soil can be an element effecting color, where the same dahlia variety grown in two different climates may look different.  Below are a variety of dahlias I have grown.

And here, an arrangement using a colorful variety of dahlias:

Below see the bodaciously beautiful Cafe au Lait dahlia, desirable for wedding work, and quite the diva.

Dahlia Cafe au Lait

     Dahlias are grown from tubers.  Similar to the fleshy roots of a peony, they are energy storage units that resemble “runty” sweet potatoes.  Which brings up the fact that they can be eaten, although I don’t recommend it!  Because they are generally easy to propagate (each tuber planted in May may produce multiple viable tubers for gifting, storage, or trade in October.  Identification of varieties can be facilitated by looking at on line sites as dahlias.net, nationaldahliacollection.co.uk, or www.dahliaaddict.com.  Perform a simple Google search and you will be rewarded with information about varieties, replete with photos, and sources for purchase.  A YouTube search provides cultural information.  Another way to gather information 

A large clump of dahlias, recently dug, and drying in the greenhouse prior to dividing into individual tubers.

about dahlias is to check sites that sell dahlia tubers such as Swan Island Dahlias, which is just one of many.  Dahlia Societies can be the source of much information about growing and showing dahlias.  In Western NY we are lucky to have the Rochester Dahlia Society (http://www.rochesterdahlias.org/).  In addition to an informative website, meetings, and sales, they offer sage advice.  For a mere $15.00 I recently joined….something I have been meaning to do for a long time.

Growing Pointers: Dahlia tubers can be planted after all chance of frost and freeze is gone.  In our climate, May 31 is usually a secure date, although I have planted anywhere frm May 1-31.  This year, we have been late to warm up, and I suspect I will have to err on later in the month.  As, I have said, tubers are like fleshy potatoes that would easily rot if frozen.  Ideally, a planting site that is well drained, amended with compost, and/ or in a raised bed is best.  Err on the side of a more acidic soil, than not.  Planting/ propagation can be done in pots or trays to get a head start on Mother Nature.  Some time in late winter, early spring, lay the tubers horizontally in a tray and barely cover with potting soil, or plant it vertically in a pot leaving the neck exposed.  These tubers will put out lush green growth from their growing point, or “eye”.  You can then cut this growth off when about 3-4 inches, being careful to leave a tiny bit of stem still attached to the tuber.  By using a clean razor blade, you can achieve a sharp cut.  The stem cutting can then be dipped in rooting hormone (or not) and potted up individually.  In 3-4 weeks, you’ll have a viable rooted plant that can be planted out, and which will not only produce flowers, but also tubers.  If you start this process early enough, you can produce many stem cuttings from one tuber.  Why do this?  Well depending on your source, tubers can range from $3.00 to even $20.00.  This is an inexpensive way to make more plants without all the expense.  Each year, new varieties are introduced, and different varieties become desirable and highly sought after.  It is not unusual for sellers of dahlia tubers to sell out within minutes of posting their availability on line.  Reminiscent of the tulip craze, it is amazing how demand guides the price!

     An alternative method of propagating dahlias is to plant single tubers or a clump of tubers directly in the soil in May, when the soil has warmed, or in a large pot.  Plant about 18 inches apart, either horizontally or vertically, and cover with about 4 inches of soil.  Do not water, or barely water initially to prevent tuber rot.  When you see green growth emerge from the soil, go ahead and begin to water.  Dahlias are thirsty plants and require plenty of water throughout the season.  They will be prolific bloomers until frost, if deadheaded or cut regularly.  Varieties will differ in height from 2.5 feet to 4.5 feet or even taller, producing a shrub that is 18-24 inches in width, and sure to fallover if not given support.  Several  important caveats: provide support on initial planting, pinch out the central stem when the plant is about 8-12 inches tall, and provide a general fertilizer at least twice in the growing season.  Support can be a stake adjacent to the tuber, a tomato cage, or if planting a row, as I do, use hortinova, a plastic netting.  Another method would be to use a Florida weave, commonly used with tomatoes.  You can add more twine as they grow, or even hill soil around the base of the plant to help with support. The lesson: apply support!  There is nothing like a WNY wind to knock down your beautiful dahlias…and it will.  When watering, if you’re able to avoid spraying water on the leaves, this will minimize the chance of fungal disease, as will removing the bottom leaves on the plant as it matures, which will allow increased air flow.

Dahlia Sweet Nathalie

Next time: Part II, more on growing dahlias in WNY, Dahlias as cut flowers, and varieties I have grown.

Stay healthy and safe.

Carrie Kling, Master Gardener

Windy Acres Horticulture, a flower farm dedicated to growing specialty cut flowers for CSA, florists and event planners, occasions as weddings and other events.  Full service, and a la carte services for the DIYer.