Larry Smith and the Riverside Gardens team talk all things pots, plants and pruning in their weekly gardening column.
You may have noticed autumnal colours starting to creep into some of the trees and shrubs in the gardens around the Goulburn Valley.
It will now depend on the weather and how spectacular the autumn display will be.
Clear, sunny, still days will see the plants go into dormancy slower, and the colour becomes more intense and lasts longer.
Contrary to what a lot of people believe, plant dormancy is caused mainly by decreasing daylight hours and not cold weather, although cold weather does play a part in it.
As the days grow shorter, deciduous trees prepare for winter and stop the production of chlorophyll, which is essential for photosynthesis.
The chlorophyll, which is green in colour, that was already present in the leaves begins breaking down into simpler compounds, which are then reabsorbed by the plant, leaving behind red, yellow and orange pigmentation in the leaf.
The cells at the base of the leaf then form a cork layer, and the plant abscises from the leaf. The plant is now dormant and will remain so until the daylight hours increase in spring and better weather arrives.
All this happens to protect the plant from the harsh elements of winter and allows them to hit the ground running to make the most of spring.
The maple sensations in our mini-golf course’s gardens are already colouring up in shades of yellow and orange, and the Chinese tallow trees will be close behind them with their vibrant red foliage. The autumn blaze maples are also already on the turn, and the October glory maples will be changing by May.
In the coloured autumn foliage, it would be hard to beat the Ginkgo trees, either straight biloba or the ‘Saratoga’ and ‘Princetown sentry’ varieties. They all colour up in a beautiful deep gold and hold their autumn foliage for quite a while.
Cercis ‘forest pansy’ makes quite a different display, with its multi-coloured autumn foliage in tones of red, apricot and gold all on the tree at the same time before they are discarded very quickly over a short period of time.
Fraxinus ‘autumn applause’ is another one that has a multi-coloured display from purplish red to mahogany. This contrasts with the ‘claret ash’, Fraxinus ‘raywoodii’, which has deep claret red foliage.
There is a huge range of acer palmatum, Japanese maples that do well in our region and colour up in various shades from deep scarlet red through to yellow and orange.
Acer palmatum ‘Seiryu’ turns a dark scarlet fiery red and is one of the last of the deciduous trees to change in our region. This can be as late as mid-June and will often hold on to the tree for about three weeks.
Acer palmatum ‘Sanko Kaku’ is a maple with a difference in that, as the foliage turns to apricot and yellow, the bark from the last few seasons of growth changes to orangish red, leaving a beautiful bare tree for the winter months.
Sapium sebiferum, the Chinese tallow tree, is a not-so-well-known tree with slightly heart-shaped mid-green leaves that turn a striking bright red and put on possibly one of the best autumn displays. This might only be rivalled by the Chinese pistachio tree, pistacia chinensis, which has leathery green leaves that change to give great autumn colour in shades of orange, yellow and red.
The year-round show pony, Lagerstroemia ‘crepe myrtle’, can also put on a good autumn display of red, yellow and orange. This comes straight from the back of their beautiful floral display that has been going all summer long and will be followed by peeling bark that leaves the tree with stark, shiny trunks and branches that also make an interesting feature.
So, if you are looking for autumn colours for your garden, now is an excellent time to look around and see what impresses you. Take some photos or bring in a few leaves so we can identify what you are looking for, or come in and have a look through the nursery and mini-golf display gardens to see the autumn display on show here.