In the evening just before sunset.
When it got darker
Reading more on lighting, many experts believe that the better time for nature photography is evening just before sunset and morning just after dawn. These are the times when you get the best of the colours, more of it and in greater variety.
Ofcourse I find it difficult to get up just after dawn so generally prefer just before sunset time. Things get better if it has just rained. Things look fresher and water droplets give a richer colour effects and contrasts.