Want High Yields from Summer-Grown Celtuce? Master These Cultivation Techniques

Celtuce is one of the most commonly eaten vegetables in our daily lives, found everywhere in vegetable markets and supermarkets. The editor likes eating it very much too. In everyday life, eating more of this green vegetable is very helpful to human health, so vegetables are a must for every household.

What Is Celtuce

Celtuce, also known as lettuce, is a variety of the lettuce species in the genus Lactuca of the Asteraceae family that can form a tender fleshy stem; it is an annual or biennial herbaceous plant. Other names include stem lettuce, lettuce shoot, green shoot, and lettuce vegetable. Production period: January to April. It originated in central or northern China. The above-ground stem is edible; the stem skin is white-green, and the stem flesh is crisp and tender. Young tender stems are emerald green, turning white-green after maturity. Mainly the tender fleshy stem is eaten; it can be eaten raw, served cold, stir-fried, dried or pickled, and the tender leaves are also edible.

Growth and Reproduction of Celtuce

1. Germination stage: from sowing to the appearance of true leaves, taking 8-10 days. The effects of temperature and light on seed germination are the same as for leaf lettuce.

2. Seedling stage: from the appearance of true leaves to the partial unfolding of 5 or 8 leaves of the first phyllotaxis, commonly known as “rosette formation”. Direct sowing takes 17-27 days; raising seedlings takes more than 30 days. The optimum growth temperature is 12-20℃, and it can tolerate low temperatures of -5 to -6℃.

3. Rosette stage: from “rosette formation” to the full unfolding of the third phyllotaxis, when the heart leaves are level with the outer leaves, taking 20-30 days. Leaf area expands rapidly, and the tender stem begins to elongate and thicken.

4. Fleshy stem formation stage: the stem expands rapidly and leaf area expands rapidly, taking about 30 days. The optimum growth temperature is 18-22℃ during the day and 12-15℃ at night; it freezes below zero degrees. During this period the shoot apex differentiates flower buds, and the flower stem begins to elongate and thicken, becoming part of the fleshy stem.

5. Flowering and fruiting stage: from bolting to achene maturity; the growing temperature is the same as that of lettuce. Celtuce is a high-temperature-sensitive type, and flower bud differentiation is greatly affected by average daily temperature. When the average daily temperature is above 23℃, flower bud differentiation is rapid. Some also believe that flower bud differentiation is related to accumulated temperature above 5℃. For varieties with different sensitivity to high temperature, the accumulated temperature required for flower bud differentiation differs when sown at different times. Plants with thicker, larger stems are more sensitive to high temperature than plants with thinner, smaller stems. Long daylight promotes bolting and flowering; under 24-hour daylight, bolting and flowering can be advanced at either 15℃ or 35℃. High temperature with long days is more conducive to bolting and flowering than low temperature with long days.

How to Cultivate Celtuce in Summer for High Yield

In order to regulate the supply of vegetables during the off-season, in recent years some places have worked out a set of new techniques for summer cultivation of celtuce, with a yield of up to 1,200 kg per 667 sq m and remarkable economic benefits. The specific methods are as follows.

1. Low-temperature germination promotion

The summer celtuce growing period coincides with the high-temperature season, so heat-tolerant varieties must be selected. Before sowing, promote germination first: soak the seeds in cold water for 8-12 hours; when the seed water absorption rate reaches 70% to 80%, wrap them in wet gauze and place them in the refrigerator compartment or suspend them 10 cm above the water surface in a well, keeping them at a low temperature of 4-5℃. After treatment for 24-28 hours, place them under suitable temperature conditions of 15-20℃ and keep them moist to promote germination (sun-drying seeds that have not passed dormancy can increase the germination rate). After 2-3 days, when most seeds have sprouted white, they can be sown.

2. Shaded seedling raising

Summer celtuce is sown at the end of June and the beginning of July. When sowing, it is best to mix the seeds with an appropriate amount of dry fine soil before sowing, sowing 1 gram of seed per 1 sq m. In case of drought, water to create sufficient soil moisture before sowing; after sowing, rake lightly and pat firm, and build a shed with straw curtains for shade to raise seedlings. On sunny days cover early and uncover late; on cloudy days uncover all day, so as to help lower temperature and preserve moisture. During the seedling stage, combine watering with 2-3 applications of diluted liquid manure. When the seedlings are about 25 days old and have 4-5 true leaves, they can be transplanted.

3. Transplanting method

Before planting, apply 3,000 kg of decomposed barnyard manure and 2,000 kg of human and livestock manure per 667 sq m, prepare the land by digging furrows and making beds, and level the bed surface. The bed width is 1.5-2 m, the furrow width is 25 cm, and the depth is 15-20 cm. In late July, choose a sunny evening; after watering the seedbed, lift the seedlings with soil and transplant them, with a plant spacing of 25 cm and a row spacing of 35 cm, planting 700-800 plants per 667 sq m. After planting, water thoroughly to settle the roots, and water again with diluted liquid manure after 2-3 days. Before the plants are established, it is best to build a shed for shade.

4. Fertilizing and watering

Summer celtuce has shallow roots and weak absorption capacity, and in addition grows rapidly in summer, so it needs more fertilizer and water; special attention should be paid to heavy fertilizer and water management. After the seedlings are established, combine drought resistance with one application of diluted liquid manure every 3 to 5 days. When the stem begins to expand, apply fertilizer and water frequently (stop watering 10 days before harvest), and spray the leaves with 0.3% potassium dihydrogen phosphate 1 to 2 times. If downy mildew is found, spray with metalaxyl at the early stage of the disease. Where conditions permit, when the celtuce rows close and the stem begins to thicken, spray with the growth regulator mepiquat chloride 2 to 3 times, which can effectively increase stem weight.

5. Harvest in batches

If summer celtuce is harvested too late, the fleshy stem may form flower buds, consuming nutrients and becoming hollow and inedible. Harvesting too early reduces yield. Generally, about one month after transplanting, when the stem expands and the stem top is level with the tips of the outer leaves, it can be harvested in batches.

For friends who grow celtuce, increasing its yield is very important. In this process, besides understanding its growth habits, understanding its fertilizing, watering, transplanting and so on is also very important. Only by comprehensively understanding some of its characteristics can its yield be better increased.