An easy care and eye catching plant, the Tree Dahlia is Dahlia imperialis, a tall perennial originally from South America.
Grown for the flowers that appear on long bamboo like canes in early winter, the Tree Dahlia is a plant that can add a little seasonal height to the garden, with very attractive flowers.
Growing from tubers, this is a plant that loves a sunny position and a humus rich soil. Plant it at the back of the border where the flowers will rise above all else in winter.
A few varieties are available, mainly to do with flower colour and form.
- D. imperialis – Mauve flowers
- D. imperialis ‘Dark Pink’ – Deep pink flowers.
- D. imperialis ‘Double White’ – Large ruffled ‘Double White’ flowers.
How to Grow Tree Dahlias – Basic Care
The best position to grow tree dahlias is in a humus rich soil, in a sunny position protected from wind. They are also best in a position where they are protected from frosts.
The stems tend to be brittle and can break easily in windy conditions, especially when in full flower.
How to plant tree Dahlias
You will either be purchasing a tuber, or you will be planting cuttings. Either way planting instructions are similar.
Plant the tuber around 10 cm deep, cover with soil and water in well.
With cuttings, the instructions are the same, the whole cutting is layed flat and covered with 10 cmd of soil.
- Water in well with a liquid seaweed fertiliser.
- Mulch around the plant to suppress weeds.
- Water during long dry spells.
Growing Tree Dahlias in pots
You can grow tree dahlias in pots however you will need a large pot, the height which can reach 4-6m (12 – 18ft) when in flower makes the plant top heavy so pots can easily topple over. Also the tubers do get large, so you will need to either divide the plant every year or two or keep potting it ip into larger pots.
Tree Dahlia Propagation
You can propagate Tree Dahlias from cutting or by dividing the tubers, or rhizomes.
Cutting are best taken near the end of winter as they begin to die back after flowering. Tree Dahlias will shoot from the nodes of the old stems if you follow this method.
- Cut the stems right back to the base of the plant.
- Trim the old foliage away.
- Cut the stems into lengths that have 2 – 3 nodes on them.
- The cuttings from lower down stem will work better than the soft ones from the top.
- Dig a shallow trench where you want the new plants to grow.
- Lay a cutting in the trench .
- Cover with around 10 cms of soil.
- Plants will shoot the next season.
You can also lay the cuttings in large pots or containers if you wish, follow a similar procedure as above.
Pruning Tree Dahlias is carried out in two ways.
End of season pruning.
The plants are simply cut back to ground level at the end of winter after flowering.
Formative Pruning.
This is carried out in summer. The new shoots are let grow to around 30 cm and then cut back to around 15 cm. This helps create a more compact plant, less likely to be damaged by wind.
Tree Dahlias are available for sale online from the following nurseries.
www.planterspatch.com.au
470 Monbulk-Silvan Road Monbulk VIC 3793
"Guaranteed mail order flowering bulbs, perennials, roses, trees, landscaping plants, garden accessories and community fundraising Austra lia-wide."
www.gardenexpress.com.au