The secret to growing exquisite dahlias

Flower farmers share their expert tips.
Close up of Dahlia 'Cafe au lait' flowers in a gardenGetty

It was the sheer magnificence of dahlias that led mother-and-daughter duo Kathryn and Mikayla Heinjus, flower farmers and founders of Gidgee Estate in The Riverina, NSW to plant their first dahlia tubers.

The flowers began to appear the following summer and it didn’t take long for the pair to realise that the blooms were just too pretty to keep to themselves, “which led us to expanding into a cut flower garden dedicated solely to dahlias,” says Mikayla.

A bunch of dahlias harvested at Gidgee Estate. (Credit: Mikayla Heinjus via @gidgeeestate Instagram)

Fast-foward to today and they’re growing more dahlias than ever. “This winter we dug up all of our dahlias and have sub-divided them in the hope to increase the amount of plants we have in the ground for summer,” says Mikayla, adding, “they are the most addictive flower to grow. Once you start, it’s very hard to stop buying and dividing.”

Here they share their expert tips for growing dahlias, keeping them healthy and even share a family secret to cutting them just so to ensure they last as long as possible in a flower arrangement.

Kathryn and Mikayla in the flower farm at Gidgee Estate. (Photographer: Georgia Rose Photography)

Like other old-fashioned flowers including roses, hydrangeas, tulips and chrysanthemums, dahlias make a wonderful addition to a cutting garden, that is, a garden designed solely for the purpose of harvesting the flowers for flower arrangements. If you find yourself spending a fortune on gift bouquets each year, consider starting a cut flower patch to create your own arrangements!

Dahlias’ place in the cut flower garden

Where to plant dahlias 

“Dahlias cope well in the sun,” says Kathryn, who says they thrive in direct sunlight in well-fertilised, free-draining soil. Most recently they planted their dahlias in a raised bed, “which worked for us this season.” At Gidgee Estate, where summer temperatures can reach 35 degrees celsius, they sometimes add shade to protect the quality of the flowers. 

What is the best time of year to plant dahlias?

Dahlias are sold as dormant, bare-rooted tubers that are best planted in spring. If you live in a frosty area, wait until the final frost has passed before planting. For Kathryn and Mikayla, the best time for planting is late October. For areas with colder winters, it may be better to hold off planting until November.

What time of year do dahlias bloom?

“Dahlias are a summer plant and tend to bloom from December through to March,” says Kathryn. 

A bunch of dahlias in different colours
(Credit: Photographer: Mikayla Heinjus)

Do dahlias require any special care during winter? 

Once cool weather and frosts hit, dahlias will begin to die back. Mikayla says that while it is possible to leave the tubers in the ground and allow them to bloom the following season, another option is to dig them up and divide the tubers.

“We lift the bulbs in mid-July so the bulbs can take the nutrients from the plant as it dies back,” says Mikayla. “We store them in crates lined with cloth, and cover them with a mix of sawdust and sand to cover them, in the hope that they develop eyes.”

A dahlia tuber ‘eye’ is a point of new growth that a plant will sprout from. “I have learnt from experience that not every tuber will guarantee a plant, as the tuber must have an eye to germinate successfully,” says Mikayla. 

What is a dahlia tuber ‘eye’?

Common dahlia pests and problems

Dahlias are fairly hardy plants to grow, but they can succumb to a range of pests and diseases. Snails are the biggest problem that Kathryn and Mikayla have encountered while growing dahlias. Luckily they have resident ducks and silky chickens on the farm to keep bugs at bay without impacting the plants.

Other general pests, such as aphids, mites and mealybugs are treated organically by companion planting alongside garlic and basil. 

When is the best time to cut dahlia flowers?

“Dahlias need to be in full bloom for flower arrangements as they won’t continue to open after picking. To ensure a long vase life, they need to be picked in the cool of the morning and each stem needs to be cut cleanly on the horizontal,” says Kathryn.“A family secret that was passed onto us was to place the stems into 5cm of very hot water until it cools.”

Dahlia flowers, once cut, can last anywhere from 4-6 days. 

hamptons front entrance with black door
Dahlias in a tall glass vase create a welcoming entrance at a Hamptons home in Melbourne’s inner east. (Credit: Photography: Suzi Appel / Styling: Michelle Hart)

Types of dahlia plants

Large dinner plate dahlias

Flowers of large dinner plate dahlias can grow up to 30cm in diameter. “The large dinner plate dahlias are hard to put in bunches, but I try to sneak some in for the sheer magnificence of the flower,” says Kathryn. Dahlia ‘Cafe au Lait’, a soft, creamy flower is a large dinner plate variety that is sought after particularly for wedding bouquets.

Close up of dahlia 'Cafe au lait' flower
Dahlia ‘Cafe au lait’ is a large dinner plate dahlia that is sought after for wedding bouquets. (Credit: Getty)

Medium dinner plate dahlias

Flowers of medium dinner plate varieties can grow up to 20cm in diameter. One of Kathryn’s favourites is Dahlia ‘Breannon’ which features coral-pink petals with touches of gold visible in the sunlight. 

Pom-pom and ball dahlias

Pom-pom dahlias, including Dahlia marshmallow, produce smaller flowers ranging from 5-7cm in diameter. The globe-shaped flowers are striking when placed in a bouquet and the structured petals are a soft, marshmallow pink shade. 

Cacti dahlias

Cacti dahlias aren’t cacti at all. Varieties including Dahlia ‘French watermelon’ feature spiky petals, which perhaps give the flower a spiny, ‘cactus-like’ appearance. 

Close up of a cacti dahlia, Dahlia Pinnata
Cacti Dahlia pinnata flower in full bloom. (Credit: Getty)

In the end, there’s only so much you can learn about dahlias before you absolutely must start planting them. Mikayla says to enjoy the trial-and-error process, “Enjoy learning about what works best for your garden and let the addiction begin!”

Gidgee Estate is an events space, floristry and working garden in Temora NSW founded by Kathryn Heinjus and her family in 2019. Through a process of trial-and-error, they have regenerated the soil and established a structured garden and cut-flower farm that they now love to share with garden lovers and garden learners alike. 

About Gidgee Estate

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