The loose, lacy-edged leaves of curly endive are slightly bitter, as are the broad leaves of its close relative, escarole. Both crops have the same growing requirements, and although you can plant them as spring crops, they are ideal for fall harvesting; frost improves the plants’ flavor and makes them less bitter.
Planting: Both curly endive and escarole prefer humus-rich soil in full sun.
For an early-summer harvest, sow seeds indoors in flats 2 months before the last frost date; thin to 6 inches apart. Four weeks after sowing, plant the 4- to 5-inch seedlings 1 foot apart, slightly deeper in the soil than they were in flats. Provide shade if the weather turns hot.
For fall crops, seed in July, about 90 days before the date of the first frost; stagger plantings every 2 weeks to extend the harvest. Water the ground thoroughly before sowing three seeds per inch; cover the seeds with 1/3 inch of sand, soil, or compost. Thin the seedlings to at least 1 foot apart in all directions. Overlapping leaves can cause the plants to rot.
Growing guidelines: Water regularly, because leaves will be tough and bitter if the soil dries out. Endive needs about 1 inch of water per week. Wet plants tend to rot, though, so soak the soil, not the foliage.
Blanching keeps light out of the plant’s interior and turns the heart a creamy yellow color. To blanch endive during the last 2 to 3 weeks of growth, tie the leaf tops together with rubber bands or twine, or cover the plant with an upturned ceramic plate. Make sure the leaves are dry when you do this, or the head may rot. Blanching produces a milder, less bitter taste, but it also reduces endive’s vitamin content.
Start by sowing seeds outdoors in late spring in a bed with deep, loose soil. Dig up the roots in fall, and cut off the tops 2 inches above the crown. Trim the roots and set them upright in boxes, deep pots, or a plastic 5-gallon bucket. Fill the containers with potting mix to the tops of the roots; add 6 to 8 inches of sand on top of that. Set the pots in a spot where the temperature stays between 60° and 70°F, and keep the sand moist. Harvest the heads when their tips peek up through the sand.
Problems: Endive is usually problem free. To avoid rot while plants are being blanched, untie plants after a rainstorm, and let the leaves dry before retying.
Harvesting: Harvest individual leaves or an entire plant when needed. Cut the plants with a knife at ground level. If you leave undamaged roots and 1 inch of stem, new growth may occur in warm weather.