Why blanching is a great gardening tool for the cook

To blanch or not to blanch? It’s a garden technique that many of us forget to do, or can’t be bothered doing.

This has nothing to do with the other kind of blanching where you plunge something into boiling water, then into iced water. Blanching the gardening technique is where you cover stems, leaves or whole vegetables to exclude light. This prevents photosynthesis and therefore the production of chlorophyll, producing a vegetable that is much more sweet and tender.

The heads of cauliflower, for example, are blanched to give them their creamy-white appearance. When not blanched, the heads develop a greeny-brown colour and can be slightly bitter. To blanch your cauliflower heads, snap 2-3 leaves over the curds while they are still small (about the size of an egg).

The stems of leeks can also be blanched to maximise the tender white part. As the plants grow, mound up soil or straw at the base. To keep soil out of the stems, tie a paper collar around each stem and gently hill the soil up around the paper and stem. Keep an eye out for slugs and snails, which like to hide inside the collars. Celery stems can be blanched in a similar fashion.

You can blanch heading lettuce and endives to produce tender hearts. About 5-10 days before you wish to harvest your lettuce or endive, draw the leaves together (make sure they are dry) and secure with string or a wide rubber band. You can also cover the plants with upturned pots, but make sure you block the drainage holes to exclude light. After five or so days (it can be a little longer in cooler weather) the vegetables will have a tender, creamy white heart.

You can also produce white asparagus by growing it in the dark. Grow your asparagus plants as usual, but when the spears start to poke out of the ground, you can either hill up around them with soil or cover them with a tub or hoops covered with black plastic. Either way, sun must be excluded to produce the white stems.

If you’re using hoops and plastic, a soaker hose down the middle of the row allows you to keep the beds well watered. Asparagus grown this way should also be well fed, as additional stress is placed on the plants.