How to Grow Radicchio? A Detailed Guide to Practical Cultivation Techniques

Radicchio is a perennial herbaceous plant of the genus Cichorium in the Asteraceae family, originating from the coastal regions of the Mediterranean, Central Asia and North Africa. It is widely grown in European and American countries, with bright colors and rich nutrition, and its taste is much more bitter than that of blanched chicory.

Radicchio is a semi-hardy vegetable that prefers a cool, humid climate. Its product is a red head of leaves. Radicchio generally yields 1000-2000 kg per mu, with a single head weighing 0.25-0.5 kg, up to a maximum of 2 kg.

During the growing period of radicchio, from the seedling stage to the rosette stage, relatively high temperatures are needed to favor emergence and rapid growth; the heading stage requires a large temperature difference, a lower night temperature (below 15°C) and short, strong daylight. During the heading stage, high temperatures (average daily temperature above 23°C), especially high night temperatures (above 20°C), very easily cause bolting and flowering, and also affect the color of the leaf head, so radicchio is suitable for planting in summer and autumn. Winter planting results in smaller heads and low yields due to the influence of temperature. Spring planting can achieve a certain yield, but improper planting will cause some plants to bolt.

I. Cultivation Season and Cultivation Methods

1. Open-field cultivation in autumn: Open-field cultivation in autumn is the main cultivation method for radicchio. Choose early and mid-maturing varieties, such as Qiuri, Indio, etc. In North China, sowing is generally done in mid-July, planting out in mid-August, and harvesting successively in October. If sown too early, heading occurs early, and because of the high temperature, the leaf head color is often not red, so the heading stage should fall between late September and October.

2. Winter cultivation in solar greenhouses: Sow in August, plant out in September, and harvest in January-February of the following year.

II. Cultivation Techniques

1. Land preparation, fertilization, and bed making: Choose loam soil with loose texture and rich organic matter content. Protected land that has been used for growing vegetables for many years needs more straw, cow manure, etc., to reduce salt damage. Radicchio has a moderate fertilizer requirement. Per mu, apply 2000-4000 kg of decomposed organic fertilizer and 50 kg of superphosphate, mix evenly with the soil, level the ground, and make flat beds 1.3 m wide and 8-10 m long.

2. Raising seedlings: According to different cultivation seasons, use different facilities and methods to raise seedlings, ensuring a daytime temperature of 24°C-28°C and a nighttime temperature above 15°C. Generally, seedlings emerge about 4 days after sowing and become established in about 30 days. The seeding rate is about 20 grams per mu.

3. Planting out: Seedlings can be planted out when they have 5-7 leaves. The planting spacing varies according to variety and cultivation season. Early-maturing varieties are planted at a spacing of 33 cm square, and mid-to-late-maturing varieties at 40 cm square. When planting in autumn, because conditions are suitable and the plants are robust, they should be planted appropriately sparsely.

4. Management after planting out: Open-field cultivation in autumn is relatively simple to manage. After planting out, water to settle the seedlings, then water again 5-7 days later to help them recover, and after the recovery watering, cultivate and weed once; to promote leaf growth during the rosette stage, apply a topdressing of nitrogen fertilizer once, with 10 kg of urea per mu; during the heading stage, strengthen water and fertilizer management, watering and fertilizing about once every 10 days depending on weather conditions, with 10-15 kg of nitrogen and potassium fertilizer per mu each time; in the later stage, topdress nitrogen and potassium at a ratio of 1:2.

5. Harvest: Early-maturing varieties are generally harvested 60 days after planting out, once the leaf head is firm. Harvesting too early results in a looser leaf head that does not meet commercial requirements and also affects yield; delaying harvest may cause head rot or bolting, causing it to lose its commercial value.

III. Storage

Radicchio can be stored for 1-2 months at a temperature of 0°C and a relative humidity of 90%-100%. Wrapping each leaf head in paper and putting it in a basket can extend the storage period, and you can also place a layer of paper and a layer of leaf heads in the basket. During storage, check and clean it once every 15 days, and promptly remove any rotten leaves or heads.