Detailed Guide to Green Amaranth Cultivation: Planting Methods and Management Points
1. Cultivation Season
Cultivation runs from spring to autumn. Spring-sown plants bolt and flower relatively late and have tender, good-quality leaves. Summer and autumn sowings tend to bolt and flower easily and produce coarse, tough leaves. In the middle and lower reaches of the Yangtze River, the sowing period is from April to June, and autumn sowing is from late July to early August. In South China, where temperatures are higher, sowing can be done from February to August. In Southwest China, sowing is from late February to late August, and in North China from late April to early September. With the widespread use of plastic tunnels and plastic film mulching, sowing can be advanced and the crop can reach the market earlier.
2. Site Selection and Land Preparation
Choose suitable soil that is relatively flat, easy to drain and irrigate, and has few weeds. Plow to a depth of 15-20 cm, apply sufficient base fertilizer, break up the soil finely and level the surface, and make flat beds about 1.5 m wide, ready for sowing.
3. Sowing
For open-field cultivation of green amaranth, sowing can be done from late February to early October. For plastic tunnel cultivation, sowing can be done throughout the year. Broadcast sowing is mostly used, and after sowing the soil is pressed firm with the feet. Because temperatures are relatively low in early spring, emergence is poorer, so the sowing rate is 3-5 kg per mu; for late spring sowing, the sowing rate is 2 kg per mu; for autumn sowing, it is about 1 kg per mu.
If the main purpose is to harvest tender stems, seedlings can be raised and then transplanted, with a planting spacing of 30 cm x 35 cm.
4. Field Management
(1) Fertilization Base fertilizer is generally 1500-2000 kg of decomposed human manure and urine per mu, plus 15 kg of superphosphate, mixed evenly with the topsoil. In addition to sufficient base fertilizer, multiple topdressings are also needed. Early spring sowings need 7-12 days to emerge, while late spring and autumn sowings of green amaranth need only 3-5 days to emerge. Generally, the first topdressing is applied when the seedlings have 2 true leaves, and the second topdressing 10-12 days later. After that, apply fertilizer once after each harvest. Nitrogen fertilizer is the main type; each time, 1500-2000 kg of dilute human manure and urine per mu can be applied, with 5-10 kg of urea added.
(2) Watering Green amaranth has a certain drought tolerance, but an adequate water supply is the guarantee of high yield and good quality, so the field should be kept moist regularly. Under normal conditions, watering with dilute manure water is combined with topdressing instead of watering with clear water alone. However, if drought occurs, irrigation should be carried out. In case of heavy rain and waterlogging, drain promptly to prevent waterlogging.
(3) Weeding The fundamental way to control weeds is to choose plots with fewer weeds for growing green amaranth. If weeds appear, they can simply be pulled by hand. Generally, this is done incidentally during harvest.
(4) Pest and Disease Control The main disease is white rust, which begins to occur in early June and is severe under high temperature and high humidity. Affected plants show yellow lesions on the leaf surface and white spore masses on the underside of the leaves. For control, spray with 50% mancozeb at 800 times dilution, or 50% thiophanate-methyl at 600 times dilution, or 40% triadimefon at 500 times dilution. Spray once every 7-10 days, for 2-3 consecutive sprays, for good control results. The main insect pest is aphids, which can be controlled by spraying 40% dimethoate at 1500 times dilution.
5. Harvesting
Green amaranth is a leafy vegetable sown once and harvested in multiple batches. Spring-sown green amaranth begins to be harvested 40-50 days after sowing. The first harvest is selective harvesting, that is, thinning out some overly dense plants. For subsequent harvests, the young tender stems and leaves can be cut with a knife. Leave a stubble of about 5 cm at the base to encourage branching for the next harvest. Spring-sown green amaranth is generally harvested for the first time when the plants are 10 cm tall and have 5-6 true leaves, for the second time after 20-25 leaves, and for the third time when the side branches have grown to about 15 cm, with a total yield of 1200-1500 kg per mu. Autumn-sown green amaranth is harvested about 30 days after sowing, generally only 1-2 times, with a yield of about 1000 kg per mu.
6. Seed Production
The cultivation management of green amaranth grown for seed is similar to that of ordinary amaranth, except that some plants are removed at harvest time, and the remaining plants are kept at a spacing of 25 cm x 25 cm; seed plants are not harvested. After flowering, seed setting, and maturity, cut the inflorescences, dry them, thresh, select the seed, and store it for later use. Amaranth sown in spring and autumn can both be kept for seed. For spring-sown seed production, sow in early to mid-April, selectively harvest off-type and inferior plants for market in mid-May, bolting occurs in mid-June, flowering in mid-July, and seeds mature in mid-August. For autumn sowing, sow in early July, and seeds mature in October. About 70-100 kg of seed can be harvested per mu.