How to sprout celtuce seeds in hot weather? A detailed guide to practical methods

Celtuce is an annual or biennial herb, 25-100 cm tall. The root is vertical and straight. The stem is erect, solitary, with paniculate inflorescence branches in the upper part, all stem branches white. The basal leaves and lower stem leaves are large, undivided, oblanceolate, elliptic or elliptic-oblanceolate, 6-15 cm long, 1.5-6.5 cm wide, apex acute, short-acuminate or rounded, sessile, base cordate or sagittate and half-clasping, margin undulate or finely serrate, gradually smaller upward, same shape as the basal and lower stem leaves or lanceolate; the leaves below the paniculate branches and on the paniculate branches are very small, ovate-cordate, sessile, base cordate or sagittate and clasping, margin entire, all leaves glabrous on both surfaces. Capitula numerous or very numerous, arranged in a panicle at the tips of stems and branches.

The involucre of celtuce is ovoid in fruit, 1.1 cm long, 6 mm wide; involucral bracts in 5 layers, the outermost broadly triangular, about 1 mm long, about 2 mm wide, the outer ones triangular or lanceolate, 5-7 mm long, about 2 mm wide, the middle ones lanceolate to ovate-lanceolate, about 9 mm long, 2-3 mm wide, the inner ones linear-oblong, 1 cm long, about 2 mm wide, all involucral bracts acute at the apex, glabrous outside. Ligulate florets about 15. Achenes oblanceolate, 4 mm long, 1.3 mm wide, compressed, light brown, with 6-7 fine veins on each face, apex acute and tapering into a slender beak, the beak filiform, about 4 mm long, nearly as long as the achene. Pappus in 2 layers, slender, slightly scabrous. Flowering and fruiting period February-September.

Celtuce has a taproot system, and after transplanting it produces many lateral roots, shallow and dense, mainly distributed in the 20-30 cm soil layer. The stem is shortened. Leaves alternate, lanceolate or long-ovate, etc., pale green, green, dark green or purplish red, leaf surface flat or wrinkled, margin entire or notched. The shortened stem gradually elongates and thickens as the plant grows; after the stem tip differentiates flower buds, the stem thickens while the flower stem elongates, forming a club-shaped fleshy tender stem. The flesh color is pale green, emerald green or yellow-green. Conical capitulate inflorescences, flowers pale yellow, each inflorescence with about 20 flowers, self-pollinating, sometimes cross-pollination also occurs. Achenes, blackish brown or silvery white, with pappus.

Autumn celtuce is sown in the high-temperature season of summer and early autumn. When the temperature is relatively high, the seeds germinate with difficulty, so special management is needed to cultivate strong seedlings. The optimum temperature for seed germination is 15°C-18°C, the maximum temperature is 28°C, and light is required. Therefore, before sowing summer and autumn celtuce, low-temperature sprouting is needed. The methods are:

1. Well-hanging method: Soak the seeds in freshly drawn well water (about 15°C) or cold water for 5-6 hours, rub and wash 2-3 times, remove the mucilage and impurities, take them out and dry them slightly, wrap them in a wet cloth bag, hang them 10-30 cm above the well water surface, keep the temperature at about 15°C, rinse with well water 1-2 times a day, and they will sprout in 3-4 days.

2. Refrigeration method: After soaking the seeds for 24 hours, rub and wash them clean, wrap them in gauze, place them in a refrigerator or refrigerated cabinet, refrigerate at 3°C-5°C for 24 hours, then place them in a cool, ventilated place, and the seeds will germinate slowly. When the young sprouts show white, spread them out in a cool, ventilated place with scattered light, and pay attention to spraying water, maintaining moisture, and preventing drying. After 2-3 days, when the embryo sprouts show pale green, they can be sown. After sprouting and hardening, the seedlings emerge uniformly and have strong stress resistance.

3. Sand-mixing method: After soaking the seeds for 1-2 hours, mix them with moist fine sand, place them in an air-raid shelter or beside a water vat, and keep them cool and moist; they will germinate in 3-4 days.

4. Irrigation and covering method: After the seedbed has been sun-baked until it turns whitish, level it and make it fine, broadcast dry seeds, cover with a thicker layer of rice straw, then press the straw down with bamboo poles or bricks. Every evening, irrigate the seedbed until thoroughly wet, and the seeds will gradually germinate in 2-3 days.

5. Growth regulator sprouting method: At high temperatures of 30°C-40°C, you can also soak the seeds in 5 mg/L gibberellin for about 8 hours, then rinse them clean with tap water, and sow them directly; the germination rate can be increased to about 80%. After sowing, set up a shade shed (do not cover on cloudy days) or a shade net, or sow under a melon trellis, or mix-sow with fast-emerging pak choi.