How to plant Onion Bulbs? A Useful Guide from Gardening Expert

How to plant Onion Bulbs?

Onion Bulbs are surprisingly easy to grow! So, how to plant Onion Bulbs for high yield? People often plant them early in the spring and harvested them from midsummer through the fall. Today, Garden How will give you step-by-step guidance for growing this vegetable effectively.

What is the best time to plant Onion Bulbs?

It is better to grow Onion bulbs early in late August, or early September, the crop of 10-15/10. You can sow bulbs in early July, however, the yield is unstable, and the tubers are small. The advantage of this crop is the high selling price and the early supply of Onion Bulbs to the market. 

How to plant Onion Bulbs?

How to plant Onion Bulbs?
Make sure about the distance between Onion Bulbs.

You need to make sure the soil does not have any weeds, thoroughly ground, finely ground, and fully fertilized with the following amount of manure: Amount calculated for 1 pole/ 500 m2: 1.5 tons of rotting manure + 12- 15 kg of phosphorus + 3-4 kg of potassium (or 20 kg of kitchen ash).

If you choose to grow Onions from seed, it is better to treat seeds before sowing. Onion seeds have many angles, thick skins, and bulges, so it is necessary to treat seeds before sowing. You should treat the seed with hot water of 40-50 o C for 10-12 hours.

To grow 1 pole of Onion, it is better to sow 80 g of bulbs on 24 m 2. The age of the Onion should not be too young, or too old. Seedling age is from 35-40 days, and the number of leaves on the tree is from 4.5 to 5 at most 6 leaves.

How do fertilize Onion Bulbs after planting?

The amount of fertilizer for Onions Bulbs for 1 hectare is: 

  • Rotten organic fertilizer: 20-25 tons of rotting organic fertilizer, with conditions, of 30-40 tons can be applied, preferably chicken manure or composted manure items. 
  • Pure macronutrient content calculated for 1 ha of Onion growing is: Pure nitrogen 60-80 kg should not exceed 100 kg; P2O5: 80-90 kg; K2O: 120 kg.

Fertilization method:

All manure + all phosphate fertilizers + 2/5 potassium fertilizers + 1/3 total nitrogen fertilizer mix well into the soil at a depth of 7-10 cm. Such a level of fertilizer can yield 30 tons of tubers/ha for the Granex variety.

Reasonable planting distance and density for Onion Bulbs

What is the best time to plant Onion Bulbs?
The spacing between Onion plants is 13–15 cm apart.

After the ground has been leveled, cleared of weeds, and raised to a bed height of 1.2–1.3 meters, distribute fertilizer into the bed surface uniformly. Having been planted in beds with four rows, the spacing between Onion rows is 22–25 cm, plants is 13–15 cm apart, and there are 21–22 thousand trees per hectare.

Planting infrequently will result in vigorous growth of the stems and leaves, sluggish production of tubers, the enormous growth of the bulbs, and prolonged maturation and drying out of the plants.

When planting, you have to dig a hole with a sharp stick, lay the Onion in it without burying it completely, and fill it with fine soil. Then, you cover the base. Growing deep root tubers is challenging.

Taking care of Onion Bulbs after planting


Depending on the type of terrain, perform 2-3 times. One hectare of land is fertilized with 24-54 kg of nitrogen fertilizer after planting and 10-15 days of deep plowing, wide across the surface of the bed.

Apply the second time: watering 42–56 kg of nitrogen after the second planting, which takes 25–30 days.

56-84 kg of nitrogen fertilizer should be plowed closely around the base of the third watering after planting for 40-45 days. Depending on when the Onion is in its growth, the concentration ranges from 0.5 to 1%. To wash the leaves after watering, it is important to use an umbrella box to lightly rinse the foliage.

Apply the first potassium fertilizer: 56–84 kg/ha, 40 days after planting. Apply potassium twice: 56-84 kg, concentration 1%, after planting, 50–60 days later, when the bulbs have grown. Stop spraying nitrogen if Onion plants grow and develop normally.


Taking care of Onion Bulbs after planting
It is necessary to water your Onions on time.

After planting, you move the water to keep the seedlings moist until they become green. Water the trench once every 7 to 10 days, depending on soil moisture and weather, starting 30 days after planting. After the soil has been saturated with water, it is important to quickly drain the water and allow the field to dry out. Stop watering one month prior to harvest.

Prevention of diseases when planting Onion Bulbs

Onion leaf spot (Stemphylium botryosum W.)

Identify Onion disease 

The disease primarily harms winter crops during the time when tubers are forming. The disease predominantly affects leaves, where it manifests as spots. When the disease first appears, the lesions have a long oval shape and are black in color. A week after the disease has appeared, the leaves are split along the middle and have dried out. The disease develops in conditions of lack of light, cloudy sky, high air humidity, and air temperature from 20-30 o C.

Onion leaf spot (Stemphylium botryosum W.)
Onion leaf spot is one of the popular diseases.

The harmful effects 

Early in the growing season, the disease destroys immature bulbs, leaves, and seedling stages of Onion plants. The initial stain has an oval form, is gray-white, and has numerous concentric rings on a gray-white background. The disease thrives when the weather is warm, the temperature is from 25-28 o C, and when the temperature is below 20 o C, the disease stops developing.

Preventive measures 

Implement synchronous integrated pest management beginning with the first stage: dry and quick treatment of Onion fields, balanced NPK fertilizer delivery, and optimum density. ill-looking leaves. Chemical treatment is an option; utilize medication in the recommended dosages (e.g., Rovral 50WP, Score 250EC) to address the condition.

Control measures 

You should apply NPK balance, plant at a reasonable density, use integrated control techniques, and don’t apply too much nitrogen. Also, you can spray Benlate 70WP during the seedling period of two to three true leaves when the plants are bent and the leaves are stretched. Then extract the plants and repeat the process.

Moreover, the tree frequently develops anthracnose after one month of planting. You need to use Benlate 70WP, Sumi – 8, etc., and you should stop spraying one month before harvest. Besides, pests on Onions Bulbs are usually aphids, except for aphids with herbal medicine Trebon 10EC…

Harvesting Onion Bulbs on time

The characteristics of the cultivar and the intended use determine when to harvest.

Young tubers can be used to prepare vegetables and salad mix 60 to 70 days after planting. But often, the range of uses will increase as the tubers ripen, ensuring productivity and quality.

Onion Bulbs are utilized as vegetables, raw materials for processing, preservation, transport, and loading on ships for export when they are ready, and the bulbs are kept until the following crop.

There are 1/4 to 1/2 of the fallen Onion plants in the field that can be picked. For a period of days leading up to harvest, the weather must be dry. Harvesting is done by hand in our nation. When the Onion is ready, dig up the plant, spread it out evenly on the ground to dry, and then gather the Onions Bulbs, concentrating on a few beds. After being cleaned and allowed to dry for a few days in a temperature range of 25 to 30 degrees Celsius, the Onions Bulbs are stacked on a scaffold with each layer being arranged in 2-3 layers with a thickness of 20 to 25 cm.

How to store Onion Bulbs?

Preserving Onions Bulbs in cold storage needs to control the temperature at 0 o C, and air humidity to 60-65%. If the temperature is above 0 o C and the humidity is above 65%, the tubers begin to germinate, the roots also grow, and the Onions Bulbs become ugly and quickly depreciate in the market.

Check your tubers frequently during storage to get rid of those that are bad, sick, or have germinated. The more dehydrated Onions Bulbs are after being stored, the more they get dry and hard, lose weight, and shrink in volume. The greater the temperature, the lower the air’s humidity level, and the more dehydrated Onions Bulbs are. When the air humidity in the warehouse is low and the ventilation is too intense, the volume of tubers decreases quickly. The ideal conditions for storing Onions Bulbs in boxes are -1°F (-2°C), 80–85% relative humidity, and a moderate ventilation rate.

Final Thoughts about how to plant Onion Bulbs at home

Garden How provided you with all of the useful information about how to plant Onion Bulbs effectively. Actually, they are a nutrient-dense food, meaning that they are high in vitamins, minerals, and antioxidants while being low in calories. Hopefully, this post can help you plant and take care of Onion better. Visit to learn more about flowers and vegetables. Thank you for taking the time to read this!

Related posts:
What are Onions good for?
Onion Anthracnose
How to grow Onions from seed?

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