OF all the summer- flowering plants, dahlias are among the most amazing. They started to bloom a week or so ago and will continue to do so deep into autumn.
In frost- free districts many will continue flowering into June.
The flowers are so flamboyant and colourful they put most other plants to shame.
This is one reason they are often planted separately in a bed on their own.
The start of the growing season last year was unusually wet, so much so that the soil in many gardens remained saturated for weeks.
Many dahlia tubers that were left in the ground over winter clearly succumbed to these appalling conditions.
I lost a few lovely varieties, mainly because of my failure to lift and store the tubers over winter.
However, those that were divided and replanted have done particularly well. Plants grown from single tubers almost always flower more prolifically than those from undivided clumps. Ours did well because the ground was first enriched with a mixture of compost, sheep manure, blood and bone fertilisers and even a generous sprinkling of poultry manure pellets.
This combination supplies all the nutrients needed by dahlias. There is no doubt about the value of continuous dead- heading.
It is this simple, easy and very satisfying task that keeps the plants blooming furiously for months.
Once the really hot weather arrived, watering ours became a priority. These easily grown plants love the combination of high- nitrogen fertilisers and plenty of water, particularly during long, dry periods.
Dahlia plants are top- heavy, mainly because of the size and weight of the blooms. The stems are also very fragile and blustery winds can cause severe damage, often snapping plants at ground level.
Stakes are not very pretty but, unfortunately, essential for supporting dahlias. I don’t like those hard, thin, black bamboo supports sold at most garden centres because they can be quite a menace. Anyone working and constantly bending among dahlias and other plants needs to be constantly on guard against serious eye injury.
If they must be used, always be careful to wrap bands of clear yellow electrician’s tape around and over those deadly tips so they can be clearly seen.
Another dependable summer- flowering group of plants is the hydrangeas. Most people in Tasmania go for the common mop- tops because they do so well here. They are also easy to look after and, if growing strongly, make marvellous dome- shaped, groundcovering weed- suppressors.
However, there are several other hydrangea species and cultivated varieties also worth a place. For at least 20 years we’ve been growing an oak- leaf hydrangea, partly because of the fascinating, pearly white, flattish flowerheads, but also because of the glorious autumn colours produced just before leaf fall.
Ours became too big over the years, finishing up so massively congested it virtually stopped flowering. Even the leaves, normally quite large and lush, became small and insignificant.
So last winter I got stuck into it with a pruning saw, cutting the entire plant right down to ground level. I thought I had killed it and was fully prepared to grub out the rotting stumps later.
However, new shoots emerged and sprouted with extraordinary vigour. Already it is 1.5m high and wide and even coming into flower. Best of all, the leaves are enormous and indicate great joys ahead as winter approaches. Other hydrangea varieties, especially
H. paniculata, were also cut back in winter to virtual stumps, but this is a perfectly normal treatment. These too are now in astonishing display, especially the remarkable grandiflora known as “Pee Gee”.
The creamy- white flowerheads are so enormous they dragged the slender but flexible branches right down to the ground. So I’ve been forced to lift them to tie them in great big, loose bundles. They still look brilliant.