AusBonsai

A few years ago during a workshop with Hiro someone asked him how to achieve autumn colour. His response was swift "dry your trees out". This was born out last year in the Dandenong ranges. Last summer was as we all know one of the hottest and driest on record in victoria, the autumn colour was unbelievable. Even my disectum maples coloured up something I have never seen before. I wonder if anyone else has any ideas on how to get the best colour out of our deciduous trees ?
Craig

Craig ,

first year down in a proper cold climate it will be interesting to see how my trees react. the large amount of rain lately has delayed autumn colour here at present. I have large liquid ambers, amber maples, trident maple, ginko, palonia on the property and nothing has started to colour yet except the viginia and boston ivy which is impressive, my neighbour said usually they should be turning by now, she also said youll regret the foot or two deep leaves once they drop i have been letting my maples dry out abit so see what happens.

Craig, if you ease off the water, have cold nights and warm clear days and allow full sun exposure autumn colour is better. Root bound trees seem to colour earlier and more vividly, I used to own a broom Zelkova that was in a rediculously shallow pot. When I was able to keep the leaves from scorching, it would always produce the most impressive colour in it's second or third year in the pot.

Cheers
Mojo

Hi Noah,
Your autumn leaves are a great resource you should treasure them. I love the leaf drop and have about 30 large deciduous trees in my garden. I rake up every last leaf and pile them on the garden beds really thickly free mulch. All the little woodland plants love to grow in thick leaf mould and it takes years to build up eventually you will get a layer of lovely black soil on your beds and you can grow anything in it. Beech and oak are the best.
Craig.

As autumn colour is the unveiling of the colours underneath the green pigment known as chlorophyll I think autumn colour has alot to do with the health of the tree through the growing season. Maybe a tree with established roots is at it's healthiest?
It seems though that the Carotenoids which is the yellow to red are produced through the growing season.
But the Anthocyanins which are the blended combinations of red and purple are produced at the end of Summer.
As growth slows down after Summer the chlorophyll pigment is not replenished and the colours underneath can now be seen.
I got the tech names of Wiki and found this quote which is slightly different to Mojo's

When the days of autumn are bright and cool, and the nights are chilly but not freezing, the brightest colorations usually develop.

If you look into how these Carotenoids and Anthocyanins are produced maybe you can get some brighter colours or understand why it seems better on Root bound trees?
Oh you might even get all the answers here! got to complicated for me?
http://en.wikipedia.org/wiki/Autumn_leaf_color

i have always been told defoliation as well as above mentioned.

Moyogi has it.
Cool nights to stimulate withdrawal of chlorophyl and dry weather to hasten the process. The best autumn colour comes from places that have cold nights with bright sunny days - Think Canada and those classic photos of brilliant maples.
So for brilliant colour wait for cool nights, ease off on watering and enjoy the spectacle unfold. The northerners will probably have to resort to a coolroom or stick some trees in the fridge each night to achieve what we take for granted.