Let’s Finally Settle The Question: Do Onions Grow Underground?

Onions Grow Underground

Have you ever stopped to wonder where the humble onion comes from? Sure, you can buy them at the grocery store or farmer’s market, but how do they grow? Are they like potatoes, buried beneath the soil? Or do they develop on a plant above ground, like tomatoes? It may seem like a silly question, but the truth is, many people don’t know the answer. So, let’s dig in and find out: do onions grow underground? Get ready to learn something new about this kitchen staple that has been bringing flavor to dishes from time out of mind.

Quick Facts About Onions

  • Onions are a member of the Allium family, which also includes garlic, leeks, chives, and shallots. They are also excellent companion plants to several herbs, fruit, and vegetables. These bulbous veggies are widely used in cooking for their distinctive, pungent flavor. Onions have been cultivated for thousands of years and are believed to have originated in central Asia.
  • The part of the plant that is most used in cooking is the bulb. The plant thrives in cool weather and is typically grown as a spring or fall crop. They require loose soil and regular watering to produce healthy, flavorful bulbs. Due to its excellent adjustability, it can be successfully grown in a variety of climates, from mild and humid temperatures to hot and dry ones.
  • There are several common types of this flavor-rich vegetable, including yellow, red, and white variations. Yellow onions are the most widely known and have a strong, pungent flavor that becomes sweeter when cooked. Red ones have a milder taste and are often used in salads and sandwiches. White onions have a very mild flavor and are a significant part of Mexican cuisine.

Solving The Mystery: Do Onions Grow Underground?

Onion Growth Stages

The short answer is: yes and no. Let’s elaborate on this matter that tends to confuse gardeners who haven’t dealt with this vegetable yet.

When we think about onions, we automatically picture the round, ball-like structure called a bulb. This part of the plant does grow underground, while the rest of it, such as the stem and leaves emerge above the ground. Yellow, red and white onion bulbs take a nice orb shape.

Clear so far? Great, then let’s take this one step further. If you wish to cultivate green onions, the situation is different. In contrast to its chubby counterparts, this variant has a smaller and slimmer bulb that grows beneath the surface. However, you want to focus on what develops above the soil: the long and valuable stalks.

It’s All About The Bulbs: Are All Onions Bulbing?

Now that we answered the question: “do onions grow underground or above?”, it’s time to move on to another dilemma about whether all varieties bulb or not. Well, it’s essential to highlight that we differentiate between two separate categories of this vegetable: bulbing and non-bulbing. Each group has its own unique characteristics and species.

  1. Bulbing onions: These are the most frequently utilized veggies you’ll find in the grocery store. As the name suggests, they form a bulb at the base of the plant, which is harvested and used in dishes. They are also further classified as short-day, long-day, or intermediate-day onions, depending on the number of daylight hours required for bulb formation.
  2. Non-bulbing onions: As you might have guessed, these varieties don’t form a bulb at the bottom of the plant. Instead, they produce clusters of small, elongated onions that can be harvested individually. The most typical vegetable in this category is the green onion or scallion. You might still think: “Okay, this is clear. But do green onions grow underground or not?”. Well, the bulb, which is not what you typically harvest the plant for grows underground, while the more valuable stalks develop above ground.

Categories of Bulbing Onions:

  1. Short-day onions: They require around 10-12 hours of daylight to form a bulb and are best grown in southern regions with mild winters and hot summers, as they require a short period of cool weather to trigger bulb development. Some popular varieties within this group include the Vidalia onion, which is known for its sweet flavor and large size, and the Texas Supersweet onion, which has a mild, almost fruity taste.
  2. Intermediate-day onions: The delicious vegetables that belong to this group need approximately 12-14 hours of daylight for bulb formation. They can be grown in a wider range of regions, including parts of the southern, central, and northern United States. The Walla Walla and Candy onions are both excellent examples in this category.
  3. Long-day onions: Lots of patience is a prerequisite to cultivating these kinds of veggies, as they only develop a healthy bulb when exposed to 14-16 hours of daylight. They are best grown in the northern regions of the United States and Canada. The Yellow Globe and Red Wing onions are prime members of this group.

Most Common Types of Onions

1. Yellow

Yellow Onions

Well-known, accessible, and easily manageable.

If you want to cultivate this type of veggie, find a location in your garden with full sun exposure and well-drained soil, preferably between 6.0 and 7.0 pH levels. Then, plant onion sets or transplants in early spring, about 1 inch deep and 4 inches apart.

Do yellow onions grow underground? Very much so! As the plant develops, make sure to keep the soil consistently moist, but not soaked. Fertilize with a nitrogen-rich product every 3-4 weeks. When the tops start to fall over, it’s time to harvest the produce. To do so, gently pull the onions out of the ground and let them dry for a few days in a warm, dry, and well-ventilated area. Once the outer layers are dry and papery, you can store the vegetable in a cool, dry, and dark place for several months.

2. Red

Red Onions

Similar to the previously mentioned variety, it’s crucial to pick a place for red onions with plenty of direct sunlight and porous soil. This plant prefers a slightly acidic environment, somewhere between pH 6.0 and 6.8.

Before planting, work some compost or well-rotted manure into the soil to provide extra nutrients. These greens are relatively simple to grow from seed, sets, or transplants. If starting from seed, sow them directly in the ground in early spring. If using sets, plant them in the ground in late spring or early summer.

It’s recommended to space them out about 4-6 inches apart in rows that are 12-18 inches far from each other. Water the onions regularly but be careful not to give them too much to drink to prevent root rot. Fertilize with a balanced fertilizer every few weeks to encourage healthy development.

3. White

White Onions

White onions are a hardy vegetable that can be grown in a variety of climates, making them a versatile crop for gardeners. When it comes to planting them, it’s important to select a location with permeable soil that’s flooded with sunlight. This variety can also be developed from transplants, sets, or seeds, starting in early spring, as the plant prefers cool temperatures.

White onions require regular watering, especially during hot and dry weather. A balanced fertilizer should be used to aid the optimal growth of the vegetable. As the bulbs begin to mature, the leaves will start to yellow and dry out. This is your sign for harvesting!

Did You Know? You Can Grow an Onion From an Onion

Yes, you heard it right! This is as budget-friendly as it gets. In case you don’t want to buy a whole new bunch of sets to plant in your garden, you can attempt to multiply the vegetable from the amount you already have. The process is quite simple and straightforward, and involves only a few steps:

  1. Choosing: Select a healthy onion that is firm and free from bruises or soft spots.
  2. Preparing: Cut off the bottom 1/2 inch of the onion, leaving the root end intact. Peel off the papery outer layers until you reach the first solid, healthy layer.
  3. Planting: Plant the onion in a container or directly in the ground, root end down and with the top exposed above the soil surface. Water the soil well and place the container or garden bed in a sunny spot.
  4. Caring: Keep the soil moist but not soggy and fertilize the plant with a nitrogen-rich fertilizer every 3-4 weeks. As the onion grows, thin out any weak or crowded stems to help it prosper.
  5. Harvesting: Once the tops of the onion plant start to turn yellow and fall over, stop watering it and let it dry out for a few days. Then, carefully dig up the bulbs, brush off any excess soil, and store them in a cool, dry place.

Recurring Problems When Growing Onions Underground

  • Onion maggots: These are rather common pests that can cause significant damage to onion crops. They are small, white, legless larvae that feed on the roots and bulbs of the plant, causing it to wilt and die. To prevent this scenario, it’s crucial to rotate crops, keep the soil free of debris, and apply insecticides as needed. Row covers may also be a great idea to protect young seedlings from adult flies, which lay eggs that hatch into maggots.
  • Fungal diseases: Onions can be susceptible to several fungal diseases, including onion smut and downy mildew, which bring about the yellowing of the leaves, stunted growth, and reduced yields. To avoid this situation, plant disease-resistant varieties, rotate crops, and make sure that the soil has adequate drainage and is well aerated. Fungicides can also be used preventatively or to treat infected plants.
  • Poor drainage: Waterlogged soil leads to rotting roots in most plants. So, for excess water to escape it’s essential to amend the soil with organic matter such as compost, avoid overwatering, and ensure that the garden bed is not in a low-lying area that may collect water.
  • Overcrowding: Planting onions too closely together can result in smaller bulbs and reduced overall yield. Therefore, to achieve the best possible results, follow the recommended spacing for the variety being grown and thin seedlings as necessary. Thinning also promotes a larger bulb size and reduces competition for nutrients and water.
  • Peeping out of the ground: Especially those new to gardening are prone to getting worried when they see the bulbs emerging above the surface. If you encounter this situation, don’t be frustrated – it is what’s supposed to happen. As the vegetable ripens, it pushes up the soil and may even become visible. The plant does this to avoid rotting, so don’t cover the produce back up.
  • Bolting: Onions can bolt or go to seed prematurely in response to stress, such as temperature changes or insufficient water. During this process, energy diverts away from the bulb and decreases the overall yield. Picking varieties less prone to bolting and providing consistent watering beside appropriate temperatures may be enough to avert this situation. Covering the soil with mulch also contributes to regulating soil temperature and moisture levels.
  • Flowering: Onions that are exposed to prolonged periods of cold temperatures or other environmental stresses are susceptible to bolt and produce a flower stalk. This occurrence deteriorates the health of the green, so it’s important to keep the plant away from extreme temperature fluctuations. Moreover, covering it up with row covers or cloths might help to manage temperatures too and protect the plant from excessively cold or hot weather.

Wrapping Up

Now that you know all about onions and how to grow them, when a friend asks, “do onions grow underground?”, you’ll be able to answer without hesitation. Also, it’s time to put your newly-acquired knowledge into practice and cultivate some delicious and flavorful greens of your own!

Don’t be discouraged if you encounter some problems along the way, as even experienced gardeners face challenges when growing crops. Remember to stay patient and keep experimenting until you find the perfect conditions for your onions. With a little effort and care, you’ll soon be enjoying fresh, homegrown veggies that will add depth and flavor to all your favorite dishes. Wishing you a bountiful harvest and many delicious meals to come!

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