When is the best time to plant spinach? A detailed guide to planting times
Spinach is divided into four types according to planting time: autumn spinach, overwintering spinach, spring spinach and summer spinach. Because varieties differ, their sensitivity to day length also differs. Once the plant's phase development is complete, it will bolt and flower, completing its reproductive growth.
Spinach planting times
1. Planting time for autumn spinach
Autumn spinach is generally sown in August-September, and can be harvested in batches 30-50 days after sowing. It is best to choose early-maturing varieties that are relatively heat-tolerant and fast-growing, such as Litou Bo, Huabo No. 1, Guangdong Round Leaf and Chunqiu Daye.
2. Planting time for overwintering spinach
Overwintering spinach is usually sown from mid-October to early November and harvested in batches around the Spring Festival. It is best to choose mid- and late-maturing varieties with strong winter hardiness, late bolting and strong cold tolerance, such as Round Leaf Spinach, Late Round Leaf Spinach, Huabo No. 1 and Liaoning Round Leaf Spinach.
3. Planting time for spring spinach
After the beginning of spring, sowing can begin once the temperature rises above 5°C. March is the suitable sowing period, and harvesting takes place 30-50 days after sowing. For varieties, it is best to choose late-bolting types with thick, broad leaves, such as Late Round Leaf Spinach, Chunqiu Daye, Shenyang Round Leaf and Liaoning Round Leaf.
4. Planting time for summer spinach
Summer spinach is usually sown in stages from May to July and harvested successively from late June to mid-September. It is best to choose Huabo No. 1, Chunqiu Daye and Guangdong Round Leaf, which are highly heat-tolerant, fast-growing and not prone to bolting.
Land preparation and bed making
Choose loose, fertile, slightly acidic loam that retains water and nutrients and has good drainage and irrigation conditions, with a pH of 5.5-7. When preparing the land, apply 4000 kg of decomposed organic fertilizer and 40 kg of superphosphate per mu, then level and finely rake it. In winter and spring, make high beds; in summer and autumn, make flat beds, with a bed width of 1.2-1.5 m.
Sowing and raising seedlings
Broadcasting is generally used. For summer and autumn sowing, soak the seeds in water for 12 hours one week before sowing, then place them in a well or in a refrigerator or freezer at about 4OC for 24 hours, then germinate them at 20-25OC; sow after 3-5 days when they have sprouted. In winter and spring, dry seeds or wet seeds can be sown. Sow 3-3.5 kg per mu.
After watering the bed surface thoroughly with bottom water, sow the seeds, then lightly rake the surface soil with a toothed rake so the seeds enter the soil, and cover the bed surface with a layer of plant ash.
After summer and autumn sowing, cover with rice straw or use a small arch tunnel covered with shade netting to prevent high temperatures and heavy rain from washing the soil. Keep the soil moist at all times; seedlings can be complete in 6-7 days. For winter sowing, when the temperature is relatively low, cover the bed with plastic film or shade netting to keep it warm and promote emergence, then remove it after the seedlings emerge.
Field management
After autumn spinach produces true leaves, pour 1 application of dilute manure water; after 2 true leaves, combine thinning and weeding with topdressing, applying light fertilizer first and then stronger fertilizer, with more decomposed manure applied in the early stage; during the peak growth period, apply topdressing 2-3 times, with 5-10 kg of urea per mu each time.
After sowing winter spinach, keep the soil moist. At 3-4 true leaves, control water appropriately to help it overwinter. At 2-3 true leaves, keep the seedlings 3-4 cm apart. Apply water and fertilizer according to seedling condition and weather, mainly with decomposed human manure and urine. In frost and ice-snow weather, cover with plastic film and shade netting to keep warm, and a small arch tunnel can be used. After the beginning of spring, choose sunny days to apply dilute decomposed manure water to prevent early bolting.
In the early stage of spring spinach, cover with plastic film to keep warm, and it can be laid directly on the bed surface. After the seedlings emerge, remove the film or change to small arch tunnel covering. For the small arch tunnel, uncover during the day and cover at night, uncover on sunny days and cover on rainy days, so the seedlings can get more light and be hardened more, and thin them in time. Apply topdressing and water; in the early stage, apply dilute decomposed human and livestock manure lightly and frequently; in the later stage, especially 15 days before harvest, apply quick-acting nitrogen fertilizer.
After summer spinach emerges, it is still necessary to cover with shade netting, covering on sunny days and uncovering on cloudy days, covering late and uncovering early, so as to help lower temperature and maintain moisture. During the seedling stage, water should be done in the morning or evening with small amounts and frequent watering. After 2-3 true leaves, apply quick-acting nitrogen fertilizer twice. After each fertilization, water with clear water to promote growth.
Pest and disease control
For aphids, spray with 40% dimethoate 1000x solution, or 50% pirimicarb 2000-3000x solution; for leafminers, spray with 50% phoxim emulsifiable concentrate 1000x solution, or 80% trichlorfon powder 1000x solution; for downy mildew, spray with 58% Ridomil 500x solution, or 75% chlorothalonil 600x solution; for anthracnose, spray with 50% thiophanate-methyl 500x solution, or 50% carbendazim 700x solution for control.
Harvesting and seed saving
Generally, once the seedlings are more than 10 cm tall, they can be harvested in batches. About 15 days before a one-time harvest, spray the leaf surface with 15-20 mg/kg of 920 and apply additional urea or ammonium sulfate, which can advance harvest and increase yield.
For spinach grown for seed, the sowing date can be slightly later than that for overwintering spinach. Drill sowing, with a row spacing of 20-23 cm. After turning green in spring, gradually pull out off-type plants and early-bolting male plants, leaving some vegetative male plants, so that the plant spacing reaches about 20 cm. During the bolting period, do not irrigate too much, so as to avoid thin, weak and lodging flower stalks that reduce seed yield. After flowering, apply topdressing, irrigate, and spray the leaves with a 1%-2% clear solution of superphosphate to make the seeds plump. After the male plants set seed, pull them out to improve ventilation and light penetration. Harvest when most stems and leaves have withered and yellowed and the seeds are mature, then after-ripen for several days and thresh.