Witloof

Witloof (Cichorium intybus L. var. foliosum) is a biennial plant of the Asteraceae family cultivated for its blanched heads, known as chicons, produced during winter forcing. The cultivation involves two distinct stages: root growth in the field and head forcing in total darkness.

Sowing in open ground typically takes place in late May or early June. Planting too early often leads to premature bolting, rendering the roots unsuitable for the subsequent forcing process.

Seeds should be sown at a depth of about 2 cm with row spacing of 30 cm. Once seedlings emerge, thinning is necessary to maintain a distance of 10–12 cm between individual plants.

Consistent soil moisture is crucial during the germination and establishment phases. While the plant is hardy, it requires a long growing season to accumulate sufficient energy reserves in the roots.

The vegetative period lasts 130 to 150 days. During this time, the plant stores inulin in its taproot, which is the primary energy source for the rapid growth of chicons during the dark forcing stage.

Witloof prefers deep, fertile, well-drained loamy or sandy soils with a neutral pH. Heavy clay soils should be avoided as they can cause root distortion and hinder the quality of the harvested produce.

Fresh manure should not be applied directly before sowing, as it promotes root rot. It is best to utilize soil that was fertilized for a previous crop to ensure stable and healthy growth.

Moderate temperatures of 18–22 degrees Celsius are ideal during the field growth stage. Ensuring proper soil structure and drainage is essential to prevent waterlogging, which is detrimental to the roots.

The forcing phase requires complete darkness to ensure the chicons remain white and mild in flavor. Light exposure causes leaves to green and develop a bitter taste due to intybin accumulation.

Relative humidity during forcing should be maintained at 85–90%, but direct water contact with the chicons must be avoided to prevent the development of bacterial and fungal rots.

Yield depends heavily on the quality and size of the roots harvested before the forcing period. An average of 4 to 7 kilograms of chicons can be expected per square meter of forcing space.

For high-quality production, roots should be 3–5 cm in diameter before forcing. Smaller roots produce weak, loose heads that fail to meet market standards for weight and texture.

The forcing process typically spans 3 to 4 weeks depending on the temperature in the forcing room. Faster growth can be achieved at higher temperatures, but this may result in less dense heads.

Modern breeding programs have produced varieties that yield firm, uniform chicons weighing 150–200 grams each. Consistent root selection is key to achieving these high-performance results.

Roots can be stored at 0–2 degrees Celsius before forcing, allowing growers to stagger the process and ensure a continuous supply of fresh produce throughout the winter months.

Gray mold (Botrytis) is the most common threat, especially during the forcing stage when humidity is high and ventilation is inadequate. Maintaining airflow is a primary prevention method.

Powdery mildew can affect the foliage during the summer growth phase, weakening the plant's vigor. Strategic crop rotation and early detection are essential for effective management.

Root rot, including white mold, frequently occurs if roots are stored with mechanical damage or under excessively damp conditions after being harvested from the field.

Wireworms pose a significant risk as they burrow into the roots, leaving wounds that invite secondary pathogens. Maintaining healthy soil conditions and avoiding persistent pests is critical.

Flea beetles may attack young seedlings, causing leaf damage. Regular hoeing and maintaining a vigorous growth rate through proper irrigation help the plants outgrow early pest pressure.

The harvesting of roots for forcing is carried out in late autumn before the ground freezes. Roots should be carefully lifted from the soil to avoid any bruising or skin damage.

After harvesting, foliage is trimmed to 2–3 cm above the crown, ensuring the apical bud remains intact, as this is where the new chicon will develop during the forcing stage.

Roots are placed upright in crates filled with sand or peat, allowing them to remain vertical and snug against one another before being moved into the dark forcing chamber.

Chicons are harvested by snapping them off at the base once they reach the desired size. It is important to harvest at the peak of density to ensure the best culinary quality.

Once harvested, the product should be cleaned of any remaining substrate and kept in cool storage at 1–3 degrees Celsius to maintain its crisp texture and mild flavor.