Growing Dahlias in the Yarra Valley
What’s a dahlia?
Dahlias are a flower farmer’s favourite because they combine beauty with abundance. They grow from underground storage roots called tubers. Think of them like potatoes — knobbly, starchy, and packed with energy for the season ahead. Once planted, each tuber will sprout into a lush plant that flowers from mid-summer right through until the first frost.
At the end of the season, you have two choices: either dig and divide your tubers to store over winter (great for multiplying your stock and avoiding rot), or leave them in the ground if your patch drains well. At Shortacre, we tend to dig ours, but both approaches can work depending on your soil and climate.
Chasing the sun
Dahlias are sun lovers. They need at least six hours of direct light each day, preferably more. Here in the Yarra Valley, our long summer days give them the vigour to put on a show. Pick a spot that isn’t shaded by trees or buildings and where the air moves freely to keep foliage dry.
Good soil, good flowers
Rich, well-drained soil is the secret. Dahlias don’t like wet feet, so avoid areas that stay waterlogged in winter or after rain. Heavy clay soils can be improved with organic matter, or you may need to mound your beds slightly to lift the tubers above damp ground.
We love Clyde Compost — it’s high quality and reliable, adding structure and life to the soil. Spread a generous layer and dig it through before planting. To maintain fertility, a dose of compost tea or a diluted seaweed solution during the growing season works wonders.
At Shortacre, we also avoid leaving soil bare. A covering of mulch, green manure, or living ground cover protects against erosion, locks in moisture, and keeps weeds at bay. In the Yarra Valley’s warm, dry spells, this extra layer makes a real difference to soil health and flower quality.
Planting time
Our cool-to-temperate climate means that spring nights can still be chilly, and the risk of frost continues well into October. At Shortacre, we hold off planting until mid-October, when the soil has warmed and the frost danger has passed. If you’re in a similar pocket of the Yarra Valley, waiting those extra weeks can mean the difference between thriving tubers and damaged shoots.
Pinch for more
Once your dahlias reach about 20–30 cm tall, it’s time to pinch out the growing tip. Simply snip off the top shoot just above a set of leaves. It feels counterintuitive, but this encourages the plant to branch out, producing more stems and ultimately more flowers. At Shortacre, we never skip this step — it’s the key to getting long, strong stems that keep blooming right through the season.
Watch for problems
Like most summer crops, dahlias are prone to a few common issues — powdery mildew, aphids, and snails among them. Don’t be discouraged: with a bit of care, they can be managed. In our next post in this series, we’ll share what to look for and how to keep your dahlias healthy throughout the season.
