Last Friday I showed my students how to make a white flower with coloured pencils. Normally I would prefer to use watercolour as a base for white flowers. It's just more delicate. But it can be done in coloured pencil. The most difficult part is not to use outlines to show the flower but only shadows and colour. This is what I made for them when I demonstrated how to do that. It's a tiny (1 inch) tiny rose. White with a hint of pink.
As you can see there are no outlines at all. The darkest shadows are at the overlaps of the petals and are quite strong. Also there's a good amount of shading under the stamens. That shading makes them pop up from the flower.
The biggest reason I don't like to make white flowers with coloured pencil is that there aren't so many subtle, very light coloured pencils. Caran d'Ache Luminance pencils however have a nice range of very light colours, almost whites... So I was happy this time I could use their Buff Titanium for the creamy centre. If you compare it to the cream pencils of Faber-Castell and Prismacolor it is whiter, less yellow. And sometimes it's just that tiny bit that will make the difference.