Endive & Escarole

Spring crop: start indoors and set it out early

Sow 1/4 inch deep in a container of sterile mix about six weeks before you intend to set plants out, and space the seedlings 1 1/2 to 2 inches apart in a flat while they are still under an inch high. Transplant when they are 2 1/2 to 3 inches tall into rows 18 to 24 inches apart, plants 9 to 12 inches apart, and water in with a starter fertilizer solution. Endive and escarole do not thrive in hot conditions; they want mean growing temperatures between 60 and 70 degrees and a uniform supply of moisture. A spring crop only pays if it reaches full size before summer heat arrives, which is exactly what the starter solution is for - a fast start and a mature plant before the heat.

Fall crop: direct sow - this is the better crop

Direct sow 1/4 inch deep in rows 18 to 24 inches apart, timed so the heads size up as the weather cools rather than in summer heat. Thin to 9 to 12 inches apart once the seedlings are about an inch high; the extras lift and transplant well enough to fill gaps. These grow well in spring and better in the fall. Heads that mature into cooling weather are milder and far less likely to bolt, and endive is very hardy and will withstand frost, so a fall sowing keeps giving harvest through early winter rather than ending at the first cold night.

Water frequently once the weather turns hot

Water frequently through hot months and keep the supply even rather than letting the bed swing between soaked and dry. Water the soil at the base of the plants and try to keep the bed surface itself from staying wet. These are cool-season plants that want a uniform supply of moisture and mean temperatures of 60 to 70 degrees, and they do not thrive under heat. A spring crop caught by summer heat with an irregular water supply is the usual way this crop is lost.

⚠ Do not overwater. UC IPM's guidance for lettuce drop, which names endive and escarole as hosts, is to avoid overly wet soils and keep the bed surface as dry as careful irrigation allows.

Thin direct-sown stands to a foot apart

When direct-sown seedlings reach about an inch high, thin or transplant them to 9 to 12 inches apart in rows 18 to 24 inches apart. Seed goes in 2 to 4 inches apart precisely so you can thin to the strongest plants rather than hoping every seed takes. This crop is blanched once its leaves have spread far enough to touch the next plant, so the spacing decides both how big a rosette you get and when the head is ready to tie. A crowded stand never builds the broad, deep heart that blanching is meant to produce.

Lettuce drop: watch for whole plants wilting and collapsing

As the heads near full size, look for older leaves wilting and then the entire plant wilting and collapsing at the base, unharvestable. Collect and remove infected plants - it is time consuming but it genuinely reduces the inoculum. Do not plant endive or escarole into ground that has just grown beans, cauliflower, celery, corn salad, fennel, pepper, radicchio or tomato. Endive and escarole are named crop hosts of lettuce drop, caused by Sclerotinia minor and Sclerotinia sclerotiorum. The fungus persists in the soil, so growing host crop after host crop in the same bed builds the reservoir that infects the next planting at the base of the plant.

⚠ Cultural control is honest about its limits: rotation, deep inversion plowing, removing infected plants and keeping the bed surface dry help against S. minor, but are not as helpful against S. sclerotiorum, whose spores are windborne and arrive from outside the bed.

Blanch the heart two to three weeks before you cut

Once the leaves have spread far enough to touch the next plant, gather the outermost leaves up over the center and tie them, or cover each plant with a container to exclude light. Allow two to three weeks. You can blanch several plants at once, so stagger them and you will not get every head at the same moment. Keeping sunlight off the center leaves reduces their green colour, and it is that loss of chlorophyll that takes out the bitterness and improves texture and flavour. Left unblanched, the spreading plants are likely to be bitter.

⚠ Tie only when the plant is dry. If the plant is not dry when you tie it, moisture is trapped in the heart and the inner leaves rot instead of blanching.

Cut at ground level once the heart has blanched, then chill it fast

After the blanched heads have developed, cut the plants at ground level and discard the tough outer leaves. Cut without waiting if the weather turns very hot or a hard freeze is expected. Wash, drip dry and bag; getting the heads down near 32F within an hour or two of cutting and holding them at 95 to 100 percent humidity buys two to three weeks of shelf life. Endive is very hardy and will withstand frost, so the harvest can run into early winter - but the crop is nearly all leaf and has a large leaf area, so it is very susceptible to moisture loss and wilts and yellows quickly once cut. Cold and humidity are what stop that.

⚠ Handle the heads gently. Cracked leaves and midribs bring on pink rib and browning at the cut end, and that damage develops after harvest rather than showing up while you are cutting.