AusBonsai

I have great difficulty getting the deep green colouration on my deciduous trees this time of year. No matter how much or what I feed, what the pH is, I just cannot get the dark green that the Japanese do. The trees are extremely healthy and vigorous. I can easily get 1.5 to 2 metres of growth if left unpruned so they obviously do not lack nitrogen. I have done experiments with other elements including Fe, Mn, Mg but have not noticed much change. The only thing I can come up with is light. Could it be possible that Australian sunlight is more intense (higher UV) and breaks down or inhibits chlorophyll production in some way?
Later in summer when the trees are under 70% shade cloth, the colour does seem to improve but still hard to get really good greens. I realize too dark a colour is also undesirable for other reasons.
I have read that in Taiwan they put their figs under strong shade 2 weeks before a show to improve the colour.
Would love to see your thoughts and experiences on this.
Thanks

I generally get very strong dark green, but primarily because of the dappled sunlight and lack of it. However, lack of sunlight will weaken the tree so I wouldn't be too concerned about it, as I would gladly swap problems with you. But yes, I have certainly noticed that we tend to get very dark green growth on our evergreens. Not sure what particular varieties you mean though. We don't grow a lot of exotics, pretty much only natives.

My Japanese maples grown in the shade house are a darker green than those grown in the sun.

Paul