Gadenin日本語Get the appWhat blanching actually does
Endive left in full light builds a strong bitter compound in its leaves alongside the green pigment. That is not a fault, it is the plant behaving normally, but it makes an unblanched head hard work to eat raw. Cutting the light off the center for a fortnight stops the pigment forming, and the new growth in the heart comes through cream to pale yellow, tender, and mild enough to eat as a salad on its own.
The change is confined to the leaves that grow while the cover is on, plus the ones already shaded by the ones above them. The outer leaves stay green and stay bitter, and they are perfectly good cooked. So blanching is not a treatment applied to a whole plant; it is a fortnight in which you let the heart grow in the dark.
Timing is everything. Blanch a plant that has not reached full size and you get a small pale heart and stop its growth for nothing. Blanch a plant that is fully grown and you get the maximum pale center in the shortest time. Wait until the rosette has stopped widening and the innermost leaves are starting to curve inwards over each other on their own.
The dry rule, which is not negotiable
Every method of blanching traps still, humid air around a dense mass of soft leaf. If there is free water sitting in the heart when you close it up, the center turns to brown slime within a week and the plant is a total loss. This is the single reason most first attempts fail, and it is entirely avoidable.
Cover only on a dry day, in the afternoon, after a run of at least two rainless days, when the leaves have no dew, no rain and no splash on them. Do not water the plant the day before. Once the cover is on, water the ground beside the plant with the spout of a can held low, never over the top. Stop watering altogether for the last few days.
If heavy rain is forecast within the fortnight, either use a cover that keeps rain off entirely, or delay the whole operation. Postponing blanching by a week costs you nothing; blanching into wet weather costs you the head.
A plant that is already showing any browning or rot at the base of the outer leaves should not be blanched at all. The cover will accelerate it. Clean the plant up, harvest it green, and cook it instead.
Four methods, and when each one suits
There is no single correct cover. What matters is that light is excluded, air can still move a little at ground level, and rain cannot collect in the heart. Choose by what you have to hand and what the weather is doing.
| Method | How it is done | Days to pale | Best used when |
|---|---|---|---|
| A plate or saucer on the heart | Lay a dinner plate flat on top of the gathered center so it presses the leaves down and shades them | 10 to 14 days | Broad-leaved plants, settled dry weather |
| Tying the leaves over | Gather the outer leaves up over the center and tie once, loosely, with soft twine or a rubber band | 12 to 16 days | Curly kinds where the plate will not sit level |
| An upturned pot or bucket | Invert an opaque pot over the whole plant, blocking the drainage hole, resting the rim on the soil | 10 to 14 days | Wet autumn weather, since it sheds rain |
| Lifting into a dark shed | Lift with the root ball intact, stand the plants close together in damp sand in the dark | 14 to 21 days | Frost imminent and heads still green |
Doing it step by step
The whole job takes a minute a plant. Work through the bed in order, and blanch only as many plants as you can eat in the following ten days, because a blanched head does not hold in the ground.
- Wait for full size and two dry days The rosette should be 10 to 12 inches (25 to 30 cm) across with the inner leaves already curving in. The foliage must be dry to the touch right down into the center before you touch it.
- Clean out the base Pull away any yellowed, damaged or soil-splashed outer leaves and remove weeds and debris from around the crown. Anything already decaying will spread fast under a cover.
- Gather and close the center Draw the outer leaves up over the heart with both hands and either tie them once around the middle with soft twine, loosely enough to slide a finger under, or set a plate down onto the gathered center.
- Mark the date on the plant Push a labeled stick in beside each plant with the date you covered it. Blanching runs on a two-week clock and guessing from memory is how heads get left until they rot.
- Check at day seven Lift the cover briefly on a dry day, look and smell. Pale leaves and a clean smell mean carry on. Any sour smell or brown, water-soaked patch means cut the head now and salvage what is sound.
- Cut on the day it is ready At 10 to 16 days the center should be cream to pale yellow. Cut the whole head at ground level and use it within a week. Leaving a blanched head covered for a third week almost always ends in rot.
Reading the result and keeping notes
A good blanched heart is heavy for its size, pale from the center out through a third of the leaves, and crisp rather than limp. If the middle is still green, the cover was letting light in at the base or the plant was not yet big enough to have a real heart to blanch. If the pale leaves are floppy and translucent rather than crisp, it went too long.
Keep a short record for each plant you blanch: the date covered, the method used, the weather over the fortnight, and the state of the heart when you cut it. Endive blanching is very sensitive to local conditions and a season of those entries will settle, for your garden, whether the plate or the pot works better and whether your reliable number of days is closer to ten or sixteen. Note the failures with the reason as best you can judge it, because a rotted heart almost always traces back to a specific wet day you can identify in the record.