Lilacs started to bloom across the state this week, and we have been receiving several questions this year that sound something like this: “Why does my lilac have white or creamy-colored flowers this spring instead of the normal purple or pink?”
Many plants, including lilac, will have flowers that change color as they age. Pink or purple flowers can fade over time to very light pink/purple (almost white) or a peachy yellow. For many seeing bleached flowers this spring, it is not developing as the flowers age. Instead, it appears to be this bleached color from the moment the flowers open. The pH of the soil can also influence bloom color in some plants, like bigleaf hydrangea. Lilac does not respond to soil pH this way. This phenomenon appears to be happening to lilac shrubs growing in a wide range of soil types.
Extreme weather can also influence flower color. Intense heat (which much of the state had earlier this month) can change pink or purple flowers to a yellow or white color. The anthocyanin pigment that contributes to much of the red coloration you see in plants is easily broken down by heat. We suspect the rapid and rather intense heat at a specific time in the development of the flowers caused the blooms to open a yellow/white color instead of the typical pink or purple.
There is not anything you can do to fix the problem, and it does not threaten the overall health of the shrub. Provided that the same weather conditions don’t happen next year, the shrub should bloom its typical color next season.
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