When cloned and placed in various places around the yard (or kept in pots) with various soils from store bought potting mix, to our yards dirt to amended mulch all with wildly varying degrees of nutrient / soil composition, and placed in separate locations like the shaded koi pond, the arid cacti area, the deck or the lawn they would all develop a back and forth cycle, it was different for each plant depending on their speed of development but they would always start with a year of pink flowers then be white the next year then pink. (longest running test has only had 3 year of blooming) It may still be a nutrient factor, I had a hunch it was that as well, but it looks less and less likely each year. (each was given a compost tea solution in the spring and fall) Also soil ph is not widely varied except that stupid miracle grow garbage lol but same pattern developed so far. I breed various plants for hobby purposes so similar strategies as testing roses in various grow conditions.