Some of my vegetables blanched at what I did to them. Not from embarrassment, but from lack of light.
To make a vegetable more tender and less bitter, consider blanching it. Plants blanche when they lose chlorophyll, which gives them their green color. Depriving plants of light for some period reduces their chlorophyll.
Other things that make plants blanche: If leaves can’t get their fill of iron, they show it by turning yellow, at first only the youngest leaves and in the spaces between the veins. Plants that are hungry for the essential nutrient magnesium also blanche, but this deficiency shows up first on the oldest leaves. The air pollutant sulfur dioxide blanches leaves, as do certain viruses. These types of blanching, from lack of a nutrient, or from a pollutant or disease, indicate unhealthy plants.
(Blanching by excluding light is not to be confused with blanching in cooking, which is the brief scalding of, say, a vegetable in boiling water or steam before freezing it.)
MANY WAYS TO BLANCHE
A few methods can be used to keep light off all or part of a vegetable to make it blanche. I blanched some leafy heads of endive by simply inverting clay flower pots over them. I also planted some so close together that their outer leaves were pushed up and over the inner ones, which then blanched.
I’ve blanched celery and leek stalks by piling soil against them, and cauliflower heads by tying together their outer leaves, or just snapping down one leaf to lie over the head. I’ve dug endive roots in fall and planted them in boxes brought down to my dark basement, where the roots pushed out pale, new sprouts. I’ve made cardboard collars to wrap around and keep light from cardoon stalks.
Blanching isn’t for all vegetables — only those whose stems or leaves we eat. Blanche a pepper plant and you’ll end up with pale leaves and tasteless fruits.
And some leafy or stalky vegetables aren’t improved by blanching. Blanche lettuce and it will be tasteless. Blanche arugula and it will lack the zip for which we grow it.
Cauliflower and celery are rarely blanched nowadays because self-blanching varieties — Golden celery and Snowball cauliflower — have been developed. Even conventional celery is rarely blanched anymore because most of us prefer the more robust flavor and texture of unblanched celery. White asparagus is now rare for the same reason.
It’s all a matter of taste (and texture).
Even vegetables that are improved by blanching cannot be blanched willy-nilly. That chlorophyll is what harvests sunlight, converting it to energy for plant growth. Young vegetables need to grow, so can’t afford to give up their sunlight.
Also, tender stems and leaves that result from blanching are more prone to rot and insect attack, whether the plant is young or old. And fully grown plants need some energy just to stay alive.
All these caveats to blanching make autumn a good time of year to consider it. Leafy and stalky vegetables should be fully grown by now, so more growth is not needed. Cold weather has slowed down life processes, so blanched vegetables can stay that way for weeks without expiring. And this same cold weather slows down insects and diseases so that they pose little threat to succulent, pale stems and leaves.