Welsh Onion Cultivation Technical Guide: Learn to Grow Welsh Onions in One Article
I. Seedling Raising: 1. Sowing Time: Depending on the different requirements for the product, sowing can be done in all four seasons. The best sowing period for high-yield Welsh onion cultivation is autumn sowing (when the average temperature over a ten-day period is stable at 16.5°C-17°C, which is exactly in early October). The climatic conditions across the north and south of the country differ, and sowing times also vary. The best time is determined...
I. Seedling Raising:
1. Sowing Time: Depending on the different requirements for the product, sowing can be done in all four seasons. The best sowing period for high-yield Welsh onion cultivation is autumn sowing (when the average temperature over a ten-day period is stable at 16.5°C-17°C, which is exactly in early October). The climatic conditions across the north and south of the country differ, and sowing times also vary. The best time is determined by the size of the seedlings before overwintering; if too large, they easily pass through vernalization and bolt the following spring, and if too small, they cannot overwinter safely. The standard for pre-winter seedlings is to grow to two true leaves and one heart leaf. Spring sowing is around Qingming Festival.
2. Preparing the Seedbed: The seedbed should be selected on flat, fertile land close to a water source with convenient drainage. Before making the beds, the seedling plot should be shallowly plowed and finely harrowed so that the top is loose and the bottom is firm. Apply 50 kg of compound fertilizer per mu as base fertilizer, along with 2.5 kg of carbofuran per mu and 0.5 kg of carbendazim powder to kill underground pests and pathogens (very important). The bed is 20-25 m long, 1 m wide inside, with a 30 cm bed ridge. After trampling the ridge firm, use an iron rake to repeatedly level the bed surface, with no clods.
3. Sowing: Before sowing, first take out the covering soil from the bed, then irrigate the bed with plenty of water (the irrigation amount must be large). After the water has seeped away, mix the seeds with sandy soil and broadcast them twice in the bed (spread evenly), then cover with soil. The covering soil thickness is 1.5 cm-2 cm, and the covering must be even. Seed usage for the seedling field is 1.3 kg per mu, which can transplant 3-5 mu of Welsh onions. On the morning of the second day after sowing, use an iron rake to lightly rake the bed surface once to prevent uneven soil covering.
II. Seedling Stage Management:
1. Autumn-sown seedlings emerge after 7 days, and spring-sown seedlings emerge after 8-12 days. Before the cotyledons straighten, control watering to avoid compaction and smothering of seedlings. During this period, if rain occurs and the soil crusts, use an iron rake to lightly break the surface crust. Wait until the cotyledons straighten before watering for the first time. Weed (herbicides cannot be used). When the seedlings grow to about 2 cm, roughly when they straighten, apply pesticides promptly to prevent fungal diseases. Generally spray once every 5 days (mainly using pesticides for treating dead roots and rotten seedlings, viruses, and gray mold). After the seedlings grow to more than 5 cm, apply urea as appropriate according to soil fertility to promote seedling growth.
2. Before winter, the main focus is on cultivating strong seedlings. The standard: plant height 8-10 cm, true leaves reaching two leaves and one heart leaf, leaves green and robust, base diameter not exceeding 0.3 cm. During this period, water 1-3 times according to soil moisture. Before freezing, water with freezing water, and spread a layer of farmyard manure, plant ash, or fine pen manure, with a thickness such that the ground is not visible and the leaf sheaths are exposed.
3. After the Beginning of Spring for autumn-sown seedlings, the roots, heart, and leaves of the Welsh onion seedlings begin to sprout. Rake the bed surface once to remove debris to prevent smothering the seedlings, achieving moisture retention, warming, and early growth. In early March, water with returning-green water, but not too early, to avoid low temperatures affecting early growth of the seedlings. Combined with watering, apply 10 kg of urea per mu to promote seedlings. From late March to early April, when seedlings are about 30 cm tall, thin them 1-2 times, thinning dense areas and filling sparse ones, maintaining a seedling spacing of 3-5 cm. From late April to early May, when seedlings are about 50 cm tall, this is the vigorous growth period of the Welsh onion seedlings. Good fertilizer and water management must be done. Urea, diammonium, compound fertilizer, etc. can be applied in stages, at least twice, up to three times, 10-15 kg each time, combined with pesticide spraying and application of compound trace element fertilizer 2-3 times. Apply pesticides promptly to prevent fungal diseases, with special attention to controlling onion maggots, onion thrips, and leafminers. Stop watering 15 days before transplanting and carry out seedling hardening to promote steady growth.
III. Transplanting and Field Planting:
1. Select a plot with high terrain, good drainage, and fertile soil, preferably oriented north-south. Apply sufficient base fertilizer. Base fertilizer can be 5000 kg of farmyard manure per mu, 100 kg of phosphate fertilizer, 10 kg of urea, 15 kg of potassium fertilizer, or 30 kg of diammonium, or 50 kg of compound fertilizer. Then plow and sun the soil to eliminate disease sources and weeds and improve fertility. Finally, open furrows with a furrow spacing of 80 cm and a furrow depth and width of about 25 cm each.
2. Transplant early at the appropriate time, generally from mid-June to early July. Water once two days before lifting seedlings. When lifting seedlings, dig deep to get the roots, or lift them in handfuls, shake off the soil, and place them flat. Discard damaged and diseased seedlings. Grade them into three levels according to seedling size, height, and thickness. When seedlings are sufficient, generally do not use third-grade seedlings. Lift, grade, and transplant as you go, so that the Welsh onion seedlings remain fresh when transplanted. The transplanting spacing should be 3-4 cm.
3. Planting Methods:
(1) Dry planting method: After opening the furrow, arrange the Welsh onion seedlings in order along one side of the furrow wall at a certain spacing, with the onion leaves lying flat against the furrow wall, then cover with soil using a hoe. The soil depth should not bury the heart leaves. After planting, trample firm. Or use a shovel to plant at a certain spacing, then trample firm. After planting, water once immediately, preferably without delay.
(2) Water planting method: Place the selected seedlings on the back ridge in one-meter handfuls, evenly arranged. First water the furrow. After the water seeps down, one person squats on the ridge back every 8-10 m to insert the seedlings. When inserting, use a rice-planting stick made from a peeled tree branch, with a "v"-shaped fork at the top. Mostly use the left hand to hold the seedlings and the right hand to hold the planting stick, using the fork to press against the fibrous roots of the Welsh onion seedlings. Taking advantage of the moist and soft soil at the bottom of the furrow, insert the Welsh onion seedlings straight down. Seedlings of different grades should be planted in different plots or in separate sections, and must not be placed together with tall and short mixed unevenly, so as to facilitate management.
IV. Management After Field Planting:
After transplanting, it is the hot season with high temperature and frequent rain. Generally no watering is done. Continuous rain can cause root rot and seedling death, so timely drainage should be carried out. If high temperature and drought occur, water to lower the temperature and promote growth. As the white stalk continues to elongate, timely earth up and topdress. The final ridge height after earthing up is 70-80 cm. When earthing up, the heart leaves must not be buried. Topdressing and earthing up are carried out at the same time. The first time should start from the Beginning of Autumn: apply 5000 kg of farmyard manure per mu and 10-15 kg of urea, then water. The second topdressing is at the End of Heat: apply 15-20 kg of urea per mu and 50 kg of cake fertilizer. The third topdressing is at White Dew. At this time, the white stalk enters the peak expansion period, and fertilizer and water management is key. Along the furrow, apply 1000 kg of human excrement and urine, 15 kg of urea, 50 kg of phosphate fertilizer, and 5-10 kg of potassium fertilizer, then water. The fourth topdressing is at the Autumn Equinox: apply 10-15 kg of urea per mu, earth up, and water. Around White Dew, spray compound trace element fertilizer, generally once every 5-7 days, continuously 2-3 times, with obvious yield-increasing effects.
V. Harvest and Storage:
Around the Beginning of Winter, the Welsh onions have grown sufficiently and can be harvested. After harvesting, bundle them in 15 kg bundles and place them in a cool, ventilated place, with 5-6 bundles per row and a 50 cm passage left between rows. If high-temperature weather occurs, untie the bundles and dry them. During storage, they fear heat but not cold, and must be protected from rain.
VI. Main Pests and Diseases:
1. Leafminer: Mainly damages leaves. The larvae burrow under the epidermis and eat the leaf mesophyll, leaving epidermal mines, which appear as white linear streaks due to loss of green color.
2. Onion thrips: Mainly damages leaves, sucking the leaf mesophyll and forming white spots. In severe cases, the entire leaf appears grayish-white due to loss of green color.
3. Onion maggot: Mainly damages the white stalk, stem disc, and roots underground, causing stem rot and leaf withering, resulting in missing seedlings and broken rows.
4. Welsh onion purple blotch: Damages green leaves. The lesions start as small white spots and gradually expand to 3-5 cm, spindle-shaped or date-pit-shaped. The largest lesions can reach 6-7 cm long, slightly sunken and dark purple, hence the name purple blotch.
5. Welsh onion downy mildew: Diseased plants are twisted, deformed, and stunted, with relatively large yellowish-white, elliptical lesions that look water-soaked. Leaves droop and dry up.
6. Welsh onion rust: Commonly known as red blight, it is a devastating disease in Welsh onion production areas. Lesions occur on the surface of tubular leaves and flower stems. Initially round, elliptical, or spindle-shaped, standing upright along the direction of the leaf veins, dark yellow gradually changing to orange-brown, raised, scattered, and varying in spot size. Affected plants become yellow-wilted, dry up, and even lodge, causing reduced yield.
The above cultivation experience is for reference only. Each region should manage according to local cultivation experience and climatic conditions.