For many plants, the reason for this is simple – reproduction.
Color in plants is primarily to attract pollinating insects, more so than to bring pleasure to the gardener. A flower that changes from pink to blue, like pulmonaria is really signaling the bees that the bloom is past its prime and not worth visiting.
But for the gardener, these color changes can create an intriguing garden design challenge – or they can simply be fun to watch.
Many plants simply fade as they age. Daffodils go from yellow to cream, tulips start bleaching out to pale shades of themselves. But some plants go through even more amazing transformations.
Pale Pollinators
Typically, pulmonaria (lungwort) and myosotis (forget-me-not) change from pink to blue as they age. The same holds true for borage, some delphiniums and mertensia (blue bells).
Hue-Changing Tulips
- Tulip ‘Green Wave’ is a Parrot tulip that initially opens a pure lime green. After a couple of days it begins to blush, and then to take on some ivory so that eventually you have a multicolored bloom of rose with green mid-ribs outlined with a ribbon of cream.
- Tulip ‘Tequila Sunrise’ is a riotous blend of grenadine red and sunshine orange, like the drink from which it takes its name. The trick here is that each bloom is different, some with mere hints of red, others only hinting at orange, and every possible combination in between.
- Tulip ‘Antoinette’ is a true chameleon, beginning its bloom as a pale yellow flower that then develops pink edges, finally maturing to a salmon color.
Multi-colored Shrubs
- R. (Azalea) ‘Hilda Niblett’ has spectacular 4” flowers that range in color from light pink to almost white to darker pink. It blooms in June and is hardy to -15 F.
- ‘Toyo-Nishiki’, a Japanese flowering quince blooms in early May in white, red, pink and white and pink, often all on the same branch. It is hardy in zones 5-9.
- Many roses bloom in more than one color at a time.
Hydrangeas – a Special Case
To some extent the gardener can control the color of hydrangea flowers.
White ones stay white, although they do take on a faint pink blush when cool weather hits. The acidity or alkalinity of the soil does not affect the color of a white hydrangea.
But the colored ones are often blue in acid soil and pink in alkaline.
The gardener has some control over this depending on what they add to the existing soil and what the pH of the soil is in which the shrub is planted. Add lime to acid soil and the pink color may appear; add aluminum to encourage bluer blossoms.
The intriguing thing is that a given shrub may develop some flowers in blue and others in pink or even a violet combination of the two.
There is a new Hydrangea paniculata ‘RENHY’ that is sometimes called the chameleon hydrangea because of its continuous color change process. Flowers emerge white, change to pink and finally deepen to a red color that will last from 3-4 weeks.
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