A cultivated love for dahlias

Cultivating a garden leads many gardeners to become collectors. Justin McLaughlin of Newport, Rhode Island, has done just that, curating a very large collection of dahlias.

McLaughlin grew up with dahlias in his mother’s garden. He began to grow his own — “fewer than 10” — in the 1970s when he lived in Naples, Italy. By 1983 and living in Virginia, he was up to about 20 dahlias.

“It wasn’t long after I started gardening in Newport that I discovered Swan Island Dahlias which became, and has remained, my principal source of tubers,” he said. “By [the year] 2000, I was close to 100. Each year after, as I dedicated more space to dahlias and learned to plant them closer together, that number grew by roughly 10 a year until I reached 210 in 2018.”

McLaughlin, the Director of the Newport Secret Garden Tour, opened his garden to the public during the tour in September, which is where I had a chance to walk amongst the living rainbow and experience his blooms first hand. What makes this collection so impressive is that dahlias can be a little tricky to grow in zones 2-7, requiring that the gardener lift the tubers after the killing frost and store them overwinter in an area protected from freezing temperatures.

A budding collection 

It turns out that McLaughlin not only grows the dahlias featured in his garden, but shares the plants in the community as well. The variety “Bride to Be”, which grow in Touro Park, are started in his basement in March, along with dahlias for fundraising plant sales, for friends and family, and of course, his own garden.

“Over the last few years that has led to planting a few more in pots — 630 this year,” he said. “I usually pot then when I can see eyes on the tubers, but if the tuber looks promising I may pot it anyway.” (The dahlia's stems will grow from buds, called eyes.)

This year there were 112 varieties of dahlias in McLaughlin’s garden. He is most drawn to the collarette varieties, which are daisy-like blooms, but with one ring of petals being flat and the inner ring being ruffled, creating a ‘collar.’ (Click here to learn about all 12 divisions of dahlias.)

“There were 43 plants representing 16 varieties in my garden this year (most of the buckets had collarettes in them this year).”

Speaking of unusual containers, McLaughlin doesn’t just plant in raised beds. “Several years ago I also started planting some in 5-gallon buckets from Home Depot. That helps to support my expanding inventory; this year I had plants in 18 pots.”

As for the dahlias not grown in pots or buckets, the rest are grown in raised beds. The roots of McLaughlin’s Newport garden began in 1985, but it wasn’t until the early ’90s when the raised beds (as they appear today) were completed.

“Three things, among others, allowed my collection to grow: (1) expanding my beds; (2) the availability of so many attractive and tempting varieties (both at Swan Island as well as at local garden shops, Agway, Lowes, Home Depot, Walmart: I’m an equal opportunity gardener — if I see something that looks interesting, I’m willing to find a home for it); and (3) my generation of extra tubers each year: it helps when the tuber is free,” he said. “Some varieties produce lots of tubers and others don’t produce any new tubers or simply fail to winter-over.  Consequently, I have more tubers from some varieties than others, and have to replace some varieties more often than others.  Inevitably, some varieties are dropped to make way for new discoveries. Interestingly, dropped varieties usually reappear in the garden several years later: such is human nature!

Tips for overwintering dahlias 

In the fall, McLaughlin waits several days after a killing frost or after Nov. 15 – whichever occurs first – to dig up the tubers. Ideally, completing this task is easier if the soil is not wet.

“I wash them thoroughly, trim-off the roots, remove as much stock as possible, and divide them as needed,” he said. “I always wait several days after trimming/dividing to allow for the plants to dry.”

McLaughlin stores his tubers in his basement, with temperatures that stay near 50 degrees Fahrenheit. (Dahlia tubers should be protected from freezing conditions.) He has tested many ways to store tubers over the winter, and the version that works the best for him is using vermiculite in paper bags or small boxes. “I add water to the vermiculite so it is moist when the tubers are placed in the bags.  I ensure that the tubers are covered by the vermiculate,” he said. “For large tuber clumps, I have successfully stored them by wrapping them in newspaper.”

Checking the tubers in January is also an option to see if the vermiculate has dried out – however, McLaughlin hasn’t had to do this. “In the spring, when I want to encourage development of eyes, I move the tubers into a space with a temperature above 55 degrees Fahrenheit,” he said.

By the time March arrives, the process will begin all over again.

More photos from McLaughlin's garden, as seen during the Newport Secret Garden Tour this past September: