For many gardeners, dahlias are like potato chips — you can’t have just one. If you’ve ever purchased a bouquet of cut dahlias, or succumbed to a potted variety at a nursery, you know that these tuberous rooted plants come in a dizzying number of sizes, forms, and colours. Local enthusiasts may grow them for their own pleasure and for a beautiful display in the late-season garden, for cut-flower bouquets, or showing at exhibitions or dahlia shows. But it’s tough to grow just one!
Unlike many of the plants we grow in our region, dahlias are not hardy here; they are very frost susceptible, so they are essentially an annual or tender perennial in our region. They grow from tubers that can be dug and stored inside every year, similarly to gladiolas and other annual bulbs and tubers, and then are replanted outside after the risk of frost is past in the late spring.
It’s good to talk to passionate growers to learn more about dahlias, so I turned to Arthur Haskins of Great Village, NS, for advice on growing these bloomers. Arthur is an ardent enthusiast, although he says he has cut down to “only 150 plants” from his maximum of 400 before he retired from the Department of Agriculture a few years back. He’s a founding member of the Dahlia Society of Nova Scotia, which was established in 1985 and has a thriving membership, and like his fellow members is a great encourager for anyone interested in growing these flowering beauties, regardless of their gardening skill level.
Dahlias come in a huge range of colours (most except true blue) and forms.
“If you can grow other flowers in your garden, you will have success with dahlias,” Arthur says. He was introduced to dahlias at a flower show many years ago where he saw beautiful blooms, some as large as 10 inches across, and others tiny at only an inch in size. He talked to one of the exhibitors, visited her dahlia garden the next day and says, “I was hooked as soon as I saw the different colours, flower forms, and sizes.” He figures his story is true for many enthusiasts who have been introduced to the plants the same way.
Dahlias will grow in a wide range of soil types, Arthur says, but prefer full sun, a well-drained soil that is supplemented with some good compost and a soil acidity (pH) of 6.5. If your garden is prone to dry conditions, which is becoming more of a norm in recent years, a good soaking once a week will benefit your plants. Arthur says, “We have some of the very best growing conditions in North America for dahlias, mainly due to that giant heat sink called the Atlantic Ocean that gives us cool summers and milder winters than most of the continent.” We might not be able to overwinter outside, but the plants do beautifully, and they provide bursts of colour when many perennials and annuals are winding down for the season.
Wanting to try a few dahlias for yourself? Arthur recommends joining a local dahlia society or following the group on social media (usually Facebook) to find reliable growing information for our region. He says, “it’s not much good getting growing ideas from England or the Southern US” as their growing conditions are very different from ours. He also says that “growing dahlias is similar to playing golf; the more you play the better your scores are, and with dahlias, the more time you spend looking after your plants, the more successful you’ll be.” Start out small with a few plants and see how much you enjoy growing them.
For new dahlia enthusiasts, there are several ways to build your stash, assuming you want to keep the tubers year after year. You can purchase tubers from local dahlia society sales in the spring, which will ensure healthy tubers and usually many different varieties from what you might see elsewhere. You can also order by mail from companies like Botanus or Veseys (both Canadian companies), and local greenhouses and garden centres sometimes carry the tubers in spring. If at all possible, avoid purchasing dahlia tubers sold at grocery stores and other big box places — these are imported from Holland, more often than not are packed in dry peat moss, and are in poor condition because they were mass harvested by machines.
If you’re looking for a little earlier bloom for your garden pots and plantings, consider purchasing green plants already growing in pots at local nurseries and greenhouses. They will cost a little more than the unplanted tubers, but you’ll have blooms as early as the middle of July with this great head start. I personally choose this route, as I grow several varieties in my extensive container plantings every year — these tend to be shorter varieties but are no less floriferous and come in a satisfying range of colours. As a bonus, some potted dahlias available locally have bronzed or chocolate foliage, adding to the plant’s allure even before they start to bloom.
You may need to stake or otherwise support taller dahlia varieties, especially once they start to flower, as they can be prone to breaking and bending in wind. Some growers use stakes, others use peony or tomato cages, but whatever you use, make sure the stake or other support is strong enough to hold the plants up. Supporting your plants gives the added benefit of providing good air circulation around the plants to avoid issues such as powdery mildew and other diseases.
The biggest challenge for dahlia growers, according to Arthur and fellow Dahlia Society members, is winter storage of the tubers. They need to be stored at between 8-10°C, and must never be frozen. Wrapping the clumps in newspapers or storing them in coarse vermiculite helps to keep them from drying out. You can also, of course, purchase new tubers every year if you have a lack of reliable storage space.
We mentioned above how there are many different sizes and forms (and colours) of dahlias available — there are close to 20 different forms, ranging from the petite ball and pompom forms to the show-stopping cactus and dinner plate varieties, which can boast flowers up to 12 inches/30 centimetres across. Dahlias come in pretty much every colour except true blue (so far), and many are two toned or boast a blend of shades. Currently, there are close to 60,000 registered, named varieties of dahlias, although obviously not all of these are readily available. There are even a few that have been bred and registered here in Nova Scotia by members of the Dahlia Society.
It can be hard to have a favourite variety or form, but they all look fabulous when planted in the garden. Arthur says two of his personal favourites are ‘Ruskin Diane’, an older variety of English yellow decorative dahlia about 4 inches across. His second favourite is ‘Magic Moment’, a beautiful, nine-inch semi cactus, white with a lavender blush. Other popular varieties usually available in our region include ‘Bishop of Llandaff’, which has deep purple-bronze foliage and blazing scarlet flowers; ‘Boom Boom Yellow’, a round and charming ball variety; ‘Lindsay Michelle’, a fringed form with yellow centres and reddish-pink tips to each petal; ‘Lifestyle’, a tall anemone form with a pompom gold centre and lavender-pink outer petals.