Effect of Transplanting Date on the Growth of Asian Vegetables

Demand for Asian vegetables is increasing due to a rapid increase in Asian population, health consciousness, and the desire for a variety of food. However, the cultivation information remains unknown to main stream growers and home gardeners. With high temperature and intense solar radiation in late summer, a suitable transplanting date is of importance to successfully establish winter vegetables in west Texas regions. A field trial was conducted in El Paso, Texas to evaluate the effect of transplanting dates (September 20, October 5, and October 20) on the growth of popular Asian vegetables [jinhan chinese cabbage (Brassica rapa subsp. chinensis), kaboko chinese cabbage (Brassica rapa subsp. pekinensis ‘Kaboko’), pak choi chinese green (Brassica rapa subsp. chinensis), and shanghai bok choy (Brassica rapa subsp. chinensis)]. One month before each transplanting date, seeds were sown in inserts containing Sunshine Redi Earth Professional Growing Mix. Seedlings were grown in a greenhouse with 1 g∙L^-1 Peters 15-5-15 Ca-Mg Special before transplanting. All plants were then grown in the field for eight weeks. The number of plants survived was recorded at three weeks after transplanting. Results showed that pak choi chinese green and shanghai bok choy all survived. About 60% and 30% of jinhan chinese cabbage plants died when they were transplanted on Sep. 20 and Oct. 20, respectively, whereas 50% of kaboko chinese cabbage plants died on Sep. 20 and Oct. 5. Jinhan chinese cabbage and pak choi chinese green plants flowered in the field trial indicating that they could be harvested sooner than the intended date. Transplanting date impacted the fresh weight of all tested Asian vegetables (P < 0.0001). On average, plants transplanted on Oct. 20 and Oct. 5 produced 66% to 86% and 10% to 39% less fresh weight of edible parts (leaves) than those on Sep. 20. In summary, transplanting plants on Oct. 5 could help plant establishment and subsequent growth of the above Asian vegetables in El Paso, Texas. Further research is needed to confirm the effect of transplanting dates on the quality (nutrient, flavor) of Asian vegetables.