Onion (Allium cepa)
Also known as: Garden onion, Common onion
The onion (Allium cepa), widely recognized for its culinary uses, also serves an educational purpose. Due to the large size and easy visibility of its cells, it is frequently used in teaching students how to operate a microscope. Additionally, it's worth noting that onions are toxic to certain animals.
In This Article
Attributes of Onion
Lifespan
Perennial, Annual, Biennial
Plant Type
Herb
Plant Height
15 cm to 45 cm
Spread
15 cm to 30 cm
Leaf Color
Green
Flower Size
2.5 cm
Flower Color
White
Images of Onion
Quickly Identify Onion
1
Cream-colored oval bulbs, 2-3 inches (5-7.5 cm) long with red, purple, or brown skin.
2
Chive-like green tops with multiple offsets and deer/rabbit resistance.
3
Small white/pink star-shaped flowers in spheroid clusters, 0.8-3 inches (2-8 cm) wide.
4
Dry capsules with black, wrinkled seeds, 0.2-0.24 inches (4-6 mm) wide.
5
Hollow tubular stem, 0.5-1 inch (1.3-2.5 cm) wide, green to bluish-green.
Scientific Classification of Onion
Phylum
Vascular plants
Class
Monocotyledons
Order
Asparagus and allies
Family
Amaryllis
Genus
Onions
Species
Onion
Planting and Growing of Onion
Care Difficulty
Easy
Watering Schedule
Every 4 days
Sunlight Requirements
Full sun
Sunshine Duration
4-8 hours
Ideal Temperature
50-75℉
Soil Type
Potting Mix, Peat Mix
Soil pH
6.5-7.5
Fertilizer Type
Balanced
Pruning Season
Spring, Summer
Pruning Area
Branches, Leaves
Pruning Frequency
2 times a year
Repotting Season
Spring
Pot Type
Plastic, Ceramic
How to Water Onion?
When watering Allium cepa, it's essential to ensure the soil is evenly moist but not waterlogged. This plant requires approximately 250 milliliters each time it's watered. Water until the soil feels consistently damp to the touch, ensuring that the moisture reaches about 6 inches deep. The key is balance; too much can cause rot, and too little can lead to dry, weak onions.
What are the symptoms of an underwatered Onion?
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What should I do if my Onion is not getting enough water?
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What are the symptoms of an overwatered Onion?
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How to save an overwatered Onion?
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What Are the Sunlight Requirements for Onion?
Allium cepa thrives best in full sun conditions, offering up to 12 hours of light exposure. This ensures the onion plants develop full and healthy bulbs, enhancing overall yield and quality of the produce.
Q1: What is the ideal lighting for Allium cepa?
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Q2: How to achieve this ideal lighting setup?
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Q3: What if these conditions are met perfectly?
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What Is the Ideal Temperature Range for Onion?
The ideal temperature range for Allium cepa, commonly known as the onion, is between 50°F and 75°F. This range allows the plant to grow optimally, promoting healthy leaf development and bulb formation. Onions require moderate temperatures as extreme cold can hinder growth and overly warm temperatures could accelerate bolting.
What Soil is Best for Onion?
Allium cepa thrives in well-drained soil to prevent waterlogging, which can cause root rot and stunt growth. A well-drained soil ensures roots have access to oxygen, facilitating healthy development and high yield. The onion plant requires nutrient-rich soil, especially high in phosphorus and potassium, to support its rapid growth and bulb formation. Enriched soil promotes vigorous growth and optimal flavor in the onions. While drainage is vital, the soil should also retain enough moisture to sustain the plant between waterings. Consistent moisture levels prevent stress on the plant, resulting in healthier foliage and bulb quality.
How to Fertilize Onion?
For Allium cepa, which is commonly known as the onion, an appropriate amount of fertilizer is essential for optimal growth. Typically, using 1 pound of a balanced 10-10-10 NPK fertilizer per 100 square feet of soil provides sufficient nutrients. Ensuring the fertilizer contains micronutrients like zinc and molybdenum can further support growth.
How to Prune Onion?
Begin by identifying any yellowed, dead, or damaged leaves on your onion plants. Use your pruning shears to snip these leaves at their base, close to the bulb, without damaging the healthy surrounding foliage. This helps the plant direct nutrients to healthy leaves and bulb development. If your Allium cepa is producing excessive top growth, lightly trim back some of the greens to encourage the energy flow to the developing bulbs. Aim to cut no more than a third of the top gently, ensuring ample foliage remains to support photosynthesis. Throughout the growing season, regularly check the progress of the developing bulbs. Prune any new growth if the plant starts to bolt or produce flower stalks, as this can redirect energy away from the bulbs. Remove flowering stalks at their base promptly.
How to Propagate Onion plant?
1
Ensure the soil is well-drained and rich in organic matter. Loosen the soil to improve aeration, and if necessary, add compost to provide nutrients for the developing plants.
2
Sow onion seeds thinly in rows, covering them lightly with soil. Maintain consistent moisture to facilitate germination, which typically takes between 7 to 14 days.
3
Carefully dig up mature onion bulbs and gently separate them. Replant the divisions at an appropriate depth and spacing, ensuring the roots are well-covered but not compacted.
How to Repot Onion plant?
1
Allium cepa, or the common onion, signals its need for repotting when its roots begin to circle the pot or grow out from the drainage holes. You may also notice a slowdown in growth or wilting foliage despite proper watering. Ideally, repotting should be done either annually or every two years during early spring or autumn, as this will minimize stress on the plant and allow it to acclimate quickly to its new environment.
2
Opt for a pot that is only slightly larger than the current one, allowing 1-2 inches of extra space around the perimeter. Ensure that the pot has sufficient drainage holes to prevent water stagnation, which can lead to root rot. A pot with good air circulation promotes healthy root development and ensures that excess water can drain away easily, maintaining an ideal moisture balance.
3
Select a loamy, well-draining soil mix that allows oxygen to reach the roots while retaining adequate moisture. A blend with organic matter like compost or peat moss is ideal, as it provides nutrients and promotes healthy growth. This soil mix will support Allium cepa's needs, prevent waterlogged conditions, and encourage robust development of the bulb.
Toxicity of Onion
Is Onion toxic to cat?
All varieties of onions are harmful to cats, with the onion (Allium cepa) being the most dangerous among them. Every component of the plant, whether above or below the soil, poses a toxic threat to felines. When a cat consumes any part of this plant, it can display symptoms of illness within 6-12 hours, which may encompass vomiting, copious drooling, diarrhea, lethargy, pale gums, and/or abdominal discomfort. Typically, veterinary intervention is necessary for a complete recovery. Cooked onions also remain perilous!
Is Onion toxic to dog?
Every part of the onion plant poses at least a mild toxicity risk to dogs; however, it is mainly the bulb—the portion most frequently prepared and consumed by humans—that generally elicits the most intense reactions. Dogs frequently unwittingly consume onions that are incorporated into meals served as table scraps. Symptoms may include vomiting, diarrhea, excessive drooling, and general gastrointestinal upset. Although these symptoms can lead to significant discomfort for your dog, it is reassuring to note that consuming onions rarely results in severe or life-threatening outcomes.
WARNING
The judgment on toxicity and danger is for reference only. We DO NOT GUARANTEE any accuracy of such judgment. Therefore, you SHALL NOT rely on such judgment. It is IMPORTANT TO SEEK PROFESSIONAL ADVICE in advance when necessary.
