Keep the white white & add blur to taste.
A white flower (or two) makes a wonderful subject on a gray day. Get there quickly if the flowers are on a magnolia tree and the wind has picked up. I was able to find a few white flowers still on the tree and decided to blur the background as much as possible. Do this the easy way by opening the camera lens to it’s maximum aperture (i.e. 3.5 or lower). Then fill the frame with a single flower, manually focus on it and watch the surrounding flowers blur out. Remember to add light through exposure compensation (+/-) to keep the white flowers from going gray. Camera settings for this shot: 28mm, f1.4 @ 8000, Exposure Comp: +1 full stop, ISO 100, WB Cloudy, Center-weighted metering.