What you see: White cauliflower with some random purple patches in the branches and stem
What it is: Bonus colors from anthocyanins, common plant pigments
Eat or toss: Eat! This is harmless. In fact, anthocyanins are good for you!
I’ve never had the pleasure of encountering surprise purple patches in my cauliflower (credit for these photos goes to Ros E., of Washington, DC), but if I ever sliced into the crunchy veg and discovered a splash of purple akin to watercolor art, well, I’d consider myself lucky.
First off, it’s so pretty! Second, it’s a harmless pigment misfire we can trace to the cauliflower’s genetics and possibly its environment. Third, these purple plant pigments—known as anthocyanins—are antioxidants, so this cauliflower is packing some bonus nutrition. (That is, if you manage to eat the pigments. Boil the cauliflower and the purple will dissolve away, leaving the veggie white or a little grayish.)
Jim Myers, a vegetable breeder and horticulture professor at Oregon State University, told me that this is a common genetic fluke in cauliflower production.
“Breeders select against it, but it always seems to be a little bit there,” he said.
Why did the purple show up?
Some plants produce anthocyanins in certain areas if conditions are right. In this dissertation, Li Wei Chiu writes that high light exposure, nutrient deficiency, wounds and low temperatures have all been shown to trigger anthocyanin production. Indeed, Johnny’s Selected Seeds alerts buyers that all cauliflower, but especially a variety called Snow Crown, can develop purpling on the head undersides if fertility or moisture aren’t right. According to the Farmers Almanac, cauliflower can turn purple or pink if exposed to too much sunlight, weather fluctuations or poor soil fertility. Even age can play a role, the Almanac folks say.
However, getting cauliflower to turn pretty colors isn’t as simple as exposing it to lots of light or fluctuating temperatures, or messing with its water intake. Generally, excess light will cause cauliflower to yellow, or take on a creamy or off-white cast, something growers avoid by making sure the leaves wrap around the head in the field. Myers said that he’s also seen purpling on the stems and branches of cauliflower that hadn’t endured any environmental stress, and that, when purpling is found on the inner branches, which would have been shaded, sunlight alone is an unlikely culprit. At the heart of the unexpected purple on Ros’s cutting board was probably a genetic predisposition to purpling.
Some cauliflower is designed to be pretty colors
When contemplating the purple plant art on your cauliflower, consider that some varieties are deliberately bred to be purple (these also come with fun names like Graffiti and Violet Queen). You may have also seen orange varieties, which pack extra beta-carotene, or green cauliflower, which gets its color from chlorophyll. According to the University of Minnesota Extension, these varieties require sunlight for their color to fully develop. Myers said that environmental stress will actually intensify the color of purple "Graffiti" cauliflower.
Jim Myers. Bagget-Frazier Vegetable Breeder Professor. Oregon State University.
Snow Crown. (F1) Cauliflower Seed. Johnny’s Selected Seeds.
Transposon Insertion At The Promoter Of A Myb Transcription Factor Results In Ectopic Anthocyanins Accumulation In Purple Cauliflower (Brassica Oleracea L Var. Botrytis). Li Wei Chiu February 2010. Dissertation. Presented to the Faculty of the Graduate School of Cornell University Snow Crown Hybrid Cauliflower Seed. Gurney’s Seed & Nursery Co.
Growing Cauliflower: Planting, growing and harvesting cauliflower. Catherine Boeckmann. The Farmers’ Almanac. From Editors response to reader questions on March 27, 2015.
The Many Colors of Cauliflower: Purple, Green, Orange, and White. Iowa State University Extension and Outreach.
Growing cauliflower in home gardens. University of Minnesota Extension. Jill MacKenzie. Reviewed in 2018.