Blanching and Forcing Chicory: Growing Pale Sweet Chicons in the Dark

Why darkness changes the flavor

Chicory leaves are bitter because of compounds the plant makes in the light, and their concentration goes up with the amount of light the leaf receives. Grow a leaf in complete darkness and it never develops the pigments or the bitter load. It comes out pale yellow-white, thin-skinned, crisp, and mild enough that people who dislike chicory will eat it.

That is the whole idea behind both operations described here. Blanching in place covers a growing plant for a couple of weeks so the inner leaves pale. Forcing goes further: you lift the root entirely, cut the leaves off, and regrow a completely new bud in the dark, which gives you the tight torpedo-shaped chicon in the middle of winter when there is nothing else in the garden.

Darkness must be complete. A crack of light down one side of a box is enough to green and toughen the leaves on that side and to make the chicon lean towards it. When people say their forcing produced loose green leaves rather than a firm pale head, light leaking in is nearly always the reason.

Blanching a heading plant where it stands

The simpler operation works on heading types still growing in the bed, and takes about two to three weeks in cool autumn weather. It will not give you a chicon; it gives you a milder, paler heart in a plant that would otherwise be sharply bitter. Do it only when the head has already firmed, because covering a loose plant just makes it rot.

The method is to exclude light while allowing air to move. An upturned bucket or pot with the drainage hole blocked, propped an inch (2.5 cm) off the ground on two stones, works better than anything sealed tight. Check underneath every few days. If the covered leaves smell sour or feel slimy, take the cover off and cut the head straight away.

1. Wait for a firm heart Squeeze the head. It should resist like a small firm cabbage. Blanching a soft, still-growing plant produces slime rather than pale leaves.
2. Dry the plant first Cover on a dry day when the foliage is dry, not after rain. Water trapped under a cover in the dark is the main cause of rot during blanching.
3. Cover completely, vent at the base Block any drainage hole with a stone or tape, then prop the rim so air can move underneath. Total darkness above, moving air below.
4. Lift the cover at two weeks In cool weather two to three weeks is right; in mild weather it can be as little as ten days. Cut as soon as the inner leaves have gone pale and before they soften.

Do not blanch every plant in the row at once. Cover two or three at a time, a few days apart, and you get a run of blanched heads over a month instead of a glut you cannot eat.

Lifting the roots for forcing

Forcing types are grown all season for the root alone. Lift them in late autumn once the plants have had several frosts, because the cold both sweetens the root and settles it into the dormancy that makes it force cleanly. Lifting before any cold gives you roots that either refuse to sprout or send up a weak, leafy shoot.

Dig them with a fork from well outside the row so you do not slice through the taproot. A usable forcing root is 1.5 to 2 inches (4 to 5 cm) across at the crown and 8 inches (20 cm) or more long. Thin roots do not carry enough stored food to make a chicon, and forked roots will not stand upright in the box. Sort as you lift and be ruthless: a poor root wastes six weeks of shed space.

Trim the leaves to about an inch (2.5 cm) above the crown, taking care not to cut into the growing point itself, and trim the tail of the root so it is 6 to 8 inches (15 to 20 cm) long and will stand in your container. Then rest the roots cold and dark for two to three weeks before forcing, packed in barely damp sand at 32 to 40F (0 to 4C). This rest period is what makes the bud break evenly.

Forcing the chicons in the dark

Set the trimmed roots upright and close together in a deep box, bucket or large pot, crowns level with each other and all facing up. Pack damp sand, spent compost or soil around them so the crowns just show. They need each other's support; a root standing alone in a wide pot leans and makes a crooked chicon.

Water once to settle the medium and then keep it barely damp, never wet. Cover with a second bucket or a lid so no light gets in at all, and move the whole thing somewhere held at 50 to 60F (10 to 16C). A garage, cellar, dark cupboard or the space under a bench in a frost-free shed all work. Warmer than 65F (18C) and the chicons come up fast, loose and hollow; colder than 45F (7C) and they simply sit there.

At 50 to 60F (10 to 16C) a chicon takes three to five weeks. Lift the cover once a week for a moment to check, then put it straight back. When the chicon is 4 to 6 inches (10 to 15 cm) tall and tight, snap it off the crown with a twist or cut it just above the root. Many roots will produce a second, smaller chicon afterwards if you put them back in the dark, and occasionally a third; after that compost the root.

Start batches a fortnight apart rather than forcing everything at once. Roots keep perfectly well in damp sand in the cold for two or three months, so a dozen roots forced in three batches gives you chicons right through the coldest part of the year.

Record the date each batch went into the box and the temperature where it sat, then the date you cut. Two seasons of that tells you exactly how many weeks your particular shed takes, which is the only number that matters for planning the next batch.

When forcing goes wrong

Almost every forcing failure comes down to one of four things: light leaking in, the wrong temperature, roots that were too small, or roots that never had their cold rest. Work through them in that order, because the fix for each is completely different and guessing wastes another month.