Having an all white garden is easy, except for what I call "color creep". No matter how diligent you are, every once in a while some color shows up when you least expect it. This pretty pink rose bud is supposed to be white. Flower color can vary based on the soil and climate and this one is definitely showing a new shade from years past. I will give it some time to see if it is just a few early blooms or if it has gone pink forever on me and will have to be moved.
There are so many beautiful plants that either bloom in all white or have green and white variegated foliage that it is easy to fill a garden bed. Technically a Moonlight Garden, as they are often called, is really a white and green garden, because there will always be foliage colors involved. Choosing a variety of shades of green help add character and interest to the garden and sometimes that pretty foliage comes with colored blooms like this variegated geranium with the red flowers. I just go through and cut off the flowers weekly to enjoy the colorful foliage.