Endive is a member of the chicory genus, of which the leaves are often bitter. You can sow them in March under glass and plant them out in May, or sow outside after June 21 for winter harvest.
During the first month of growth, endive should not be exposed to temperatures below 50 F (10 C) or the plants will soon make flowers instead of nice green heads. Seeds sown after June 21 won't make flowers anymore.
The green leaves are rich in vitamin A and C and minerals and can be cooked or used raw in salads. Some gardeners bleach the center leaves by putting a flower pot upside down on the plants a few weeks before harvesting.
Let one or two plants stand to make flowers. You cannot eat these plants but the blue flowers are beautiful.
- Endive Wikipedia