Gardening glossary
Blanching
Two completely different garden traditions use the word "blanching." In the kitchen it means a brief plunge in boiling water before freezing vegetables. In the growing patch it means the opposite — covering or earthing-up parts of a plant to keep them out of the light. Either way, the effect is to lighten colour and soften texture.
Why blanch a growing crop. Light triggers chlorophyll production and, in some plants, the synthesis of bitter compounds. Keep the light away and the tissue stays pale, mild, and tender. Specific crops where blanching is part of standard practice:
- **Celery.** Wrap stalks in cardboard collars, newspaper, or earth-up the rows once the plants are 30 cm tall. Three to four weeks later the stems are pale yellow-white and much milder. - **Leeks.** Earth-up steadily through the growing season, or plant in deep holes, to extend the white shank below soil level. - **Endive and chicory.** Cover heads with an upturned pot or plate for 10–14 days before harvest. The inner leaves go pale and sweet. - **Forced rhubarb.** Cover crowns in late winter with a tall bucket or specialised forcing pot. The complete darkness produces those pale pink, tender stems that fetch a premium price. - **Cauliflower.** Once heads start to form, snap or tie outer leaves over the curd to protect it from the sun, which would yellow and toughen it. Modern "self-blanching" varieties have leaves that curl naturally over the curd. - **Forced chicons (witloof).** Belgian chicory roots are lifted, trimmed, and forced in complete darkness in a cool cellar to produce tight, blanched chicons over 3–4 weeks.
How to blanch cleanly:
- **Wait until the plant is sturdy.** Blanching weakens a plant — never blanch young or struggling specimens. - **Keep the cover dry.** Soggy cardboard against a stem invites rot. Air gaps and ventilation matter. - **Time it tight.** Most blanching takes 2–4 weeks. Longer than that and you risk the plant collapsing or rotting from the base up. - **Earthing-up alternative.** For root and stem crops, drawing up loose soil or dry straw against the lower stem is often easier and safer than collars.
Skip blanching for any crop where bitterness is the point — endive lovers and dandelion harvesters often go the other way.