Etiolation

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


As seedlings first emerge from the soil, they tend to be white. Exposure to sunlight soon allows chlorophyll to be activated in photosynthesis, turning the plant green. That initial white shoot is etiolated.


Most of us have seen seedlings growing without enough sunlight, often on a windowsill. It struggles for sunlight, growing taller and taller, until it falls over, a pale version of what it might have been. The growing tips of all plants are attracted to light and will stretch out towards it. If enough sunlight is absorbed by the plant’s chlorophyll, photosynthesis can occur and normal growth will be seen.

Etiolation (சஞ்சீவி சிவகுமார்) CC BY-SA 4.0

Insufficient light

If there is not enough sunlight, plant hormones called auxins go into high gear. Those growing tips grow faster than normal, seeking 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 during etiolation, in an effort to find sunlight. The entire plant will become pale yellow and eventually turn white. The auxins also prevent lateral growth.


Culinary etiolation

Sometimes white plants are more desirable than green ones. Sometimes long straight growth is wanted. 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 own garden plants for more tender flavor.