Dahlias’ heat tolerance is well suited to a changing garden

Dahlias’ heat tolerance is well suited to a changing garden

The dahlia was declared the national flower of Mexico in 1963 and has become one of our most popular garden flowers.

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The dahlia, native to Mexico and Guatemala, was declared the national flower of Mexico in 1963 and has become one of our most popular garden flowers.

David Jack is a third-generation dahlia grower who works at Ferncliff Gardens in Mission, so I asked him for his insight on why they’ve become so popular. He said few other flowers offer such a wide range of vibrant colors and color patterns in so many flower shapes and sizes. Not only do they make a great display in our gardens, but they also make wonderful cut flowers.

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The current and growing appreciation for cut dahlias is certainly verified at United Flower Growers in Burnaby, the second largest flower auction in the world. Dahlia stems make up a large portion of all lots sold this time of year.

I was curious to know if certain flower shapes resulted in better cutting, and Jack said that varieties with flower heads between 10 and 20 cm in size are ideal for florists. He also stated that perhaps 75 percent of all dahlias grown in the garden or in dahlia farms are used to make bouquets. While commercial growers often eliminate small side shoots to encourage longer, sturdier stems, home gardeners can simply harvest the longer stems for a continuous supply of beautiful cut dahlias in late summer and fall.

Dahlia
Dalia gum.

She mentioned that traditionally, you put the cut flowers in very warm water at first so they drink quickly and last longer. He laughed and agreed, adding that floral preservatives help too, but for many years they cut them up, put them in water and admire their beauty.

When asked if he had some favorites for cut stems, Jack named Ferncliff Ebony, which is the blackest red; Clearview Sarah, white with pink petal tips; Ferncliff Rusty, a deep rusty orange type, with globular flowers; and Ferncliff Gumdrops, light yellow.

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Dahlias are very heat and drought tolerant, so they are ideal plants for hot summers like we are experiencing this year, but there are still some issues to watch for. Thrips and aphids are two of the most common insect problems, he said. We used to joke about how easy it is to control aphids, but thrips are a big challenge — especially in home gardens — because there are so few pest control products left on the local market to deal with. Picking old and spent flowers is also important for insect control.

Mildew is also a big problem at this time of year, and Jack mentioned the importance of watering in the morning and keeping the foliage dry at night whenever possible. He recommended deep, thorough watering when you can, taking into account current watering restrictions. He also suggested removing some of the lower foliage to increase air circulation around the stems and leaves.

One of the best domestic pest control products is Safer’s 3 in 1 Garden Spray which helps control aphids, mites and fungal diseases.

Feeding dahlias at least weekly is crucial, he said. They are under a lot of stress at this time of year, and to keep the plants healthy and continually producing flowers, they need extra nutrients. Something like Miracle Gro’s Bloom Booster 15-30-15 formula is crucial this time of year, but by the end of September, it’s important to stop feeding, as well as wean them off excess water to harden them for the early frost.

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Dave and Sheila Jack
Dave and Sheila Jack Photo courtesy of Dave and Sheila Jack

One concern — for overwintering purposes — is that a lot of gardeners raise them too early, Jack said. In the Lower Mainland, the end of October or November is the ideal time to extract them. His advice on digging is to first cut all the dahlia stems to a height of about 30cm above the ground. Second, dig a good-sized trench around the root ball so it can be easily lifted with a fork.

The soil mass should be cleaned as carefully as possible, exposing only the tubers. At this stage, it is not recommended to wash the tubers; It is best to keep it dry. Finally, place them separately in a cool, well-ventilated area to dry completely – often fanning them as well before wrapping them individually in newspaper. The newspaper breathes and helps protect the tubers. Store in a cool room that can be kept at a temperature above freezing, but below 15°C. Around mid to late April, you’ll be ready to replant them for another stunning display.

Ferncliff Gardens has been one of our outstanding dahlia breeders and growers for three generations. Many of their dahlia varieties can only be found on their website: ferncliffgardens.com

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This year’s crop is still growing and will be harvested this fall for sale next spring. You can place your orders online to ensure some of their great varieties are in stock.

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