Etiolation

Etiolation describes how plants become long and white due to growing in too little light.

Etiolation (சஞ்சீவி சிவகுமார்) CC BY-SA 4.0

As seedlings first emerge from the soil, they tend to be white. Exposure to sunlight activates chlorophyll used in photosynthesis, turning the plant green.

​Insufficient light

Most of us have seen seedlings growing without enough sunlight, often on a windowsill. They struggle for sunlight, growing taller and taller, until they fall over, pale versions of what they might have been.

Without enough sunlight, plant hormones (auxins) go into high gear, inhibiting lateral growth and pushing stem tips to grow faster in their search for light. In doing so, the spaces (nodes) between each leaf or stem will grow too long and become feeble. The leaves will also become elongated as they search for sunlight. Entire plants become pale yellow and eventually turn white.

​Culinary etiolation

Sometimes white plants are more desirable than green ones. Sometimes long, straight growth is what shoppers and chefs want. Belgian endive and celery are examples. In the culinary world, this is called blanching. Rhubarb, chicory, and asparagus are also commonly etiolated.

Etiolated Belgian endive CC BY-SA 4.0

You can use etiolation as a sign that plants are not getting enough light. You can also use it to blanch your garden plants for a more tender flavor.