Plant of the Month--March: DAHLIAS
For dramatic spreads of colour in summer and autumn dahlias are hard to beat. Named after the Swedish botanist, Dr Anders Dahl, they're in the family Asteraceae, which is part of the daisy family. These wonderful
flowers originated in the mountain ranges of Mexico, Guatemala and Columbia, before becoming popular throughout the world.
There are hundreds, if not thousands, of different cultivars and hybrids of dahlias. There are about 30 species of Dahlia. This tuberous-rooted perennial plant is characterised by the different flower types. Dahlias come in many lovely shades including one that’s nearly black, and there are bi-colour ones as well.
Jenny Parish lives in Winchelsea, near Geelong in Victoria, and is a Dahlia specialist. It’s become a real addiction for her. There are 20,000 Dahlia plants on her farm, and 1,700 different ones.
Jane and Jenny looked at some particular flower types. They looked at some dahlias called ‘decorative’. Some of these have small flowers, but some can be as big as 50 cm across. One decorative dahlia they looked at was Dahlia ‘Golden Leader’ which had lots of flowers. Another decorative one with lots of flowers was Dahlia ‘Alpine Charm’.
Jenny had beautiful dahlias because she cares for them by using animal manure because it encourages worms, and as she says “With worms you've got good, healthy soil.”
Jenny recommends staking and tying all dahlias to protect them because they fall over if a strong wind comes up. The tall varieties can grow as high as 1.8 metres, so they definitely need staking.
Dahlias start to flower from around Christmas to early January, so you can plant them in October or November. It’s about eight weeks from planting to flowering. Jenny says that dahlias last about a week inside as a cut flower and make a lovely display.
Among the flower types Jane and Jenny looked at were the ‘cactus’, the ‘anenome’ which looks a bit like a Japanese windflower Anemone hupehensis, and the ‘Pompon’ which are shorter. Jenny says the pompon variety copes a lot better with rain than the taller ones because when they get full of rain or water they don't drop. Tall ones just topple over if it’s windy or wet unless they’re staked and tied.
Jenny says that the most important tip to remember when people are planting the tubers is that you don't water them until they yo up about 15 centimetres high, unless the soil is really dry, because they can rot before they begin to grow.
Dahlias flower through to the end of April, first week of May, then Jenny suggests that you start to cut them back to about half their height, just to tidy up the garden. By the time you do that, it's then time when their leaves change colour to cut them off at ground level.
If your soil is well drained you can leave the dahlias in and dig them up early October and put them back. But if your soil gets wet in the wintertime, they'll rot, so they’ll need to be lifted. If tubers are lifted, they need to be covered with dirt or sawdust because if tubers are left uncovered they can dry out completely.
Gardeners need to consider the flower type, but also the plant size and weather resistance when choosing which varieties to plant. Dahlias provide a great display in the garden and they repay fully any care you give them, with their wonderful varied blooms of the most amazing colours.