Dahlia cultivation blossoms in spring
As we emerge from the depths of the pandemic and seasonal rainstorms and enter the spring season, we are free to renew the optimism and creative urges of gardening.
There are several ways to respond to those urges, so it's helpful to focus.
A really good option at this time of the year is to develop your landscape by adding dahlias, which have great appeal as garden plants and grow very well in the Monterey Bay area. This is the ideal time of the year to plant dahlias, so let's do a “deep dive” into this genus.
The dahlia genus is within the Aster or Composite plant family (Asteraceae or Compositae), which also includes the sunflower, daisy, chrysanthemum and zinnia. The dahlia is native to Mexico, which has declared it as its national flower.
The genus includes 42 species. The familiar garden dahlia (the pinnata type) includes more than 50,000 cultivated varieties, reportedly the result of crosses of two species: D. coccinea and D. sorensenii.
Hybridizers have created a large and ever-growing number of cultivated varieties with many unique characteristics. Intense hybridization and genetic modification have increased the dahlia's “inflorescence, forms of ray flowers, diversity of colors, size of individuals, and flowering time.” The accompanying photos, provided by the Monterey Bay Dahlia Society, provide a glimpse of the extraordinary diversity of this genus.
Garden dahlias are bushy perennials, growing from tuberous roots to heights ranging from 12 inches to 6 feet, depending on the variety. They bloom in the spring, reaching their peak by late August.
Dahlias generally need the support of a stake to maintain their height. The usual practice, when installing a tuber, is to insert a bamboo or similar stake nearby, carefully not piercing the tuber.
A less visible approach is to install a 1-inch diameter plastic pipe next to the tuber, with the pipe's top visible just above ground level. Later, when plant support is needed, insert a thin
bamboo stake into the pipe and tie the plant stem to the stake.
The larger dahlias, from 2 to 6 feet tall, are appealing in the landscape. They can be grouped as a drift or installed in small clusters throughout the garden. Many gardeners will include a personal selection of blossom colors and forms, while some would opt for a mass effect of a preferred color or form. There are many choices.
The smaller dahlias, from 1 to 2 feet tall, can be featured as border plants or grown in containers.
All dahlias succeed very well as cut flowers. Some varieties have been bred to produce many blooms, while other varieties are oriented to smaller numbers of high-quality blooms for competitive shows. Your choices should reflect your objectives.
Dahlia stems turn brown in the winter, usually by mid-November in the Monterey Bay area. In cold climates, a heavy frost kills dahlias, but in the Monterey Bay area's moderate climate, gardeners can cut the old stems to the ground and leave the tubers in the ground to regrow in the spring.
Another option is to dig the tubers to relocate or spread the plants in the garden, or to share tubers with other gardeners. For information about cultivation, see AdvanceYour Knowledge (below).
Mark your garden calendar
The Monterey Bay Dahlia Society will hold its annual tuber sale from 9-11 a.m. April 15 in front of the Red Apple Cafe in the Deer Park Shopping Center, 783 Rio Del Mar Blvd., Aptos. This event will be held outdoors rain or shine.
This exceptional annual event is an excellent opportunity to acquire reasonably priced tubers of locally grown dahlias, cultivated by society members, some of whom are commercial growers, outstanding hybridizers, and leaders of the local and national societies of home gardeners who appreciate dahlias.
“Countless farms advertise/open their tuber sales first to their newsletter subscribers and then to their followers, and finally on their websites,” said Monterey Bay Dahlia Society President Julie Eufemi. “Still, they consistently sell out of certain varieties within seconds, with all their stock gone in minutes of when they go `live.' Tubers in your shopping cart aren't yet yours and often disappear as you rush to check out.”
When you shop in person, however, the tubers you put in your basket are yours to buy.
“The tubers are organized by size and have pictures of what the flower will look like once the tuber grows, Eufemi said. “We also have members available to talk dahlias and answer questions.”
The society will admit shoppers in small groups to ensure an uncrowded shopping experience. Still, it's good to arrive early to select from the widest selection. This event is a pleasant way to add wonderful color to your garden.
Advance your knowledge
To learn about dahlias, visit www.dahlia.org and pull down Grow and Know menus. As you explore the wealth of information on this site, look especially at the amazing “ADS Dahlia Classification and Number Guide,” which can be found under Know/Classification.
For a basic review of recommended practices for cultivating dahlias in the local climate, visit the Monterey Bay Dahlia Society's website at mbdahlias.org, go to the resources menu and click on “How to Grow Dahlias.” This website also has information about joining the society, which is a social resource for continued learning about cultivating dahlias and sharing plants.
For a lively online video presentation on cultivating dahlias, browse to youtube. com, search for “Dahlia Growing 101” and scroll down a little to “Dahlia Growing 101: How to Grow Great Dahlias!”
The knowledgeable presenter provides a tutorial on growing these plants. The video runs
for 32 minutes and covers all aspects of cultivation. The speaker talks quickly, so you might take notes or replay the video to absorb all she offers. Hint: scroll below the video and click on “Show More” for links to a list of the topics.
Reminder: The Garden Conservatory will present the webinar, “Piet Oudolf at Work,” at 11 a.m. April 13. This virtual event will be a conversation between two long-time collaborators of the renowned Dutch garden designer Piet Oudolf: Laura Ekasetya of Lurie Garden and Meredith Simpson will discuss Oudolf's methods, inspiration and projects. His work will be featured in a soon-to-be-published major monograph, Piet Oudolf at Work. The book offers fresh insight into the work and creative practice of Oudolf, both from a horticultural and artistic perspective, showcasing high-profile and lesser-known gardens.
Webinar registration costs $5 for Garden Conservancy members and $15 for general admission. The fee for both the webinar and a copy of “Piet Ourdolf at Work” is $70. For information and to register, visit gardenconservancy.org/.
Tom Karwin is a past president of Friends of the UC Santa Cruz Arboretum and the Monterey Bay Iris Society, a past president and Lifetime Member of the Monterey Bay Area Cactus & Succulent Society, and a Lifetime UC Master Gardener (Certified 19992009). He is now a board member of the Santa Cruz Hostel Society, and active with the Pacific Horticultural Society. To view daily photos from his garden, https://www.facebook.com/ongardeningcom-566511763375123/. For garden coaching info and an archive of On Gardening columns, visit ongardening.com. Email your comments or questions to gardening@karwin.com.