Four Acre Farm is selling dahlia tubers at the Slow Food Earth Market on August 18

Earth market farmers Tom Christie and Dominique Northam are sharing the dahlia varieties that bring a vibrant array of colours to their Four Acre Farm near Dungog.

They will have a range of tubers for sale at the Slow Food Earth Market Maitland in The Levee on Thursday between 8.30am and 1pm, or until sold out.

The farmers have been able to share the tubers with the community thanks to the plant's ability to reproduce.

"When you plant one it makes a clump under the ground and you get 8 to 10 of them," Mr Christie said.

"We like them because the flowers are so beautiful and there is so much variety in terms of colours and size."

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The couple will plant their Dahlia crops at the end of September, in anticipation for a flowering sensation from December to April.

They suggest anyone who buys their tubers does the same.

"Usually once the garlic comes out we plant them in there, which is at the end of September," Mr Christie said.

"The first flowers usually come in September and they keep going until April. We will have them for sale between the earth market and the shop (The Flower Shop Dungog)."

Each plant can produce between 15 and 20 flowers over the season.

Related: Champion dahlia has been blooming for half a century

"They do take a bit of looking after. Some need more water than others, some have big fat leaves that need more water," Mr Christie said.

Mr Christie encouraged gardeners to put a stake in to support the plant, saying it became top heavy when the flowers grew and could easily blow over in the wind.

He said the plant doesn't like heavy clay soil, so pick a well-drained spot.