United Kingdom 
why have my red asers turned green
13 Jul, 2010
United Kingdom
why have my red asers turned green
13 Jul, 2010
Usually not enough light - they need bright light to retain their colour, although full hot sun will scorch the leaves. Maybe the surrounding plants have grown more and are now preventing as much light getting to the acer. This assumes the plant isn't suffering from drought.
13 Jul, 2010