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From Seed to Harvest: How to Grow Bunching Onions

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Are you a vegetable garden enthusiast dreaming of adding a burst of flavor to your culinary creations? Look no further than the humble bunching onion. Bunching onions, also known as allium fistulosum, welsh onions or Japanese bunching onions, are vibrant and versatile vegetables are a must-have in any garden.

Whether you’re a seasoned gardener or a newbie with a green thumb, this comprehensive guide will equip you with all the knowledge you need to know to learn how to grow bunching onions from seed to harvest. 

From selecting the perfect onion varieties to harvesting the edible leaves, we’ve got you covered. 

Choosing the Right Onion Variety

Before you dive into the exciting process of growing bunching onions, it’s important to choose the type of onion variety that will thrive in your garden. 

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While many of these varieties are related to regular onions, they won’t bulb up the same way, so they require less time to reach maturity. If you’re interested in growing full size onions, check out my full post here on How to Grow Onions

  • Tokyo Long White Bunching Onions- Specifically bred for cooler climates and will excel in areas with shorter growing seasons, this bunching onion has wonderful flavor. 
  • Ishikura Bunching Onion– this onion variety offers striking colors and unique shapes. This cold hardy bunching onion has a mild flavor that’s great for so many uses. 
  • White Lisbon– If you’re aiming for larger bunching onions, consider this variety. It’s one of the earliest producers and can be grown just about anywhere. 

Lastly, don’t forget to consider the growth habit of the onion varieties. Some varieties, like “Ishikura Improved,” are known for their long green stalks, making them ideal for bunching and garnishing purposes. Others, such as “White Lisbon,” have a more compact growth habit, making them suitable for smaller gardens or containers.

Where to grow bunching onions

As with all crops, these small onions have specific needs for optimal growth. Here are the factors consider when planting these hardy plants:

  • Consider the climate and growing conditions of your region (most seed packets or onion sets will have info regarding your zone)
  • Location: Consider where you’ll be growing these perennial plants. Full sun is best but partial shade can work in some areas as well. 
  • Many varieties of bunching onions are pretty enough to grow in flower beds as a border, so consider this!
  • Space saver: Since bunching onions don’t require the same space as typical spring onions, they can be grown easily in containers and other small spaces. 
  • Start indoors: In early spring, onions can be started indoors about 6 weeks before the last frost is expected. This will help shorten the growing season outdoors. As with most plants started indoors, be sure to harden off before you transplant seedling. You can also wait and direct sow in the garden or container after danger of frost has passed. 

Proper Soil Preparation

Before you can begin planting your bunching onions, it’s crucial to prepare the soil properly. Proper soil preparation will create an ideal environment for your onions to thrive and produce bountiful harvests. Here are some key steps to follow when getting your soil ready for planting.

  • Clear the planting area of any weeds or debris. Remove any rocks, sticks, or other obstructions that could impede the growth of your onions. It’s important to provide a clean and clutter-free space for your plants to establish themselves.
  • Test the soil pH. Bunching onions prefer a slightly acidic soil with a pH level between 6.0 and 7.0. You can easily test the pH of your soil using a soil testing kit available at most garden centers. If the pH level of your soil is outside the preferred range, you can adjust it by adding lime to raise the pH or sulfur to lower it.
  • Improve the soil’s structure and drainage by incorporating organic matter such as compost or well-rotted manure. This will help loosen compacted soil, enhance moisture retention, and provide essential nutrients for the onion plants. Work the organic matter into the top 6 to 8 inches of soil using a garden fork or tiller.
  • Consider enriching the soil with a balanced fertilizer before planting. Onions have specific nutrient requirements, and a fertilizer with equal amounts of nitrogen, phosphorus, and potassium can provide them with the necessary nourishment. They’re also heavy feeders, so don’t skip good quality vegetable food. 

By properly preparing the soil, you’re creating an optimal growing environment for your bunching onions. The next step is to learn how to plant them, ensuring that they have the best possible start to their journey from seed to harvest.

How to Plant Bunching Onions

To maximize the success of your bunching onions, it is crucial to learn the proper way to plant them. After you have prepared the soil, it’s time to focus on the planting process itself. By following these guidelines, you can ensure that your bunching onions get off to a great start on their journey from seed to harvest.

  • Create furrows in the well-draining soil that are about 1/4-1/2 inch deep. These furrows should be spaced about 3-4 inches apart, providing enough room for the group of bunching onions to grow and develop.
  • Unlike the large bulb of a common onion, bunching onions can be grown in bunches, so sprinkle 4-6 bunching onion seeds in each furrow. 
  • Once you have planted the seeds, cover them with a thin layer of soil, gently patting it down to ensure good seed-to-soil contact.
  • Water the furrows thoroughly to settle the soil around the seeds. It’s important to keep the soil consistently moist but not waterlogged throughout the growing process. Adequate moisture will help the seeds germinate and promote healthy root development without the risk of root rot (particularly once the seeds have germinated and are growing). 

Now that you have successfully planted your bunching onions, it’s time to move on to the next steps in their care and maintenance. 

Watering and Fertilizing Bunching Onions

Watering and fertilizing techniques are essential for the continued growth and success of your bunching onions. As you may already know, after you sow seeds, it’s important to water the surface of the soil thoroughly to settle the soil around the seeds.

The goal is to keep the soil consistently moist throughout the growing process, but be cautious not to water log it. This is why having well-drained soil is so crucial. Maintaining the right level of moisture will encourage the seeds to germinate and promote healthy root development.

Moving forward from the initial planting stage, you’ll want to prioritize the watering and fertilizing aspects of caring for your bunching onions. One effective technique is to water deeply and less frequently.

Instead of shallow watering every day, give your bunching onions a good soak once or twice a week. This allows the water to penetrate deeper into the soil, encouraging the roots to grow stronger and more deeply anchored.

Not sure how to best water your garden space? Check out my full post on The Best Watering Systems for Gardens.

When it comes to fertilizing, remember that these kinds of onions need a good supply of nutrients to thrive. One way to provide the necessary nourishment is by applying a balanced fertilizer before planting. This will give your bunching onions a strong start. As they continue to grow, you may also consider giving them a boost by applying a slow-release, nitrogen-rich fertilizer.

Harvesting Tips for Bunching Onions

As you near the time for harvesting your bunching onions, there are a few key tips to keep in mind to ensure a successful yield. Remember, the care you’ve taken in providing consistent moisture and adequate nourishment will play a vital role in the quality and abundance of your final harvest.

When it comes to harvesting bunching onion plants, timing is everything. These versatile vegetables can be harvested at various stages of growth, depending on your preferences. If you prefer a milder flavor, you can start harvesting when the greens reach around 6-8 inches in height. However, if you prefer a stronger, more pungent flavor, you can let them grow taller, anywhere up to 12 inches. Check the information from the variety of bunching onion that you chose to grow to see the estimated time to harvest. 

  • To harvest the complete onion, the best way is to loosen the soil around the base of the plants. Gently work a fork or a trowel into the ground, taking care not to damage the bulbs. Once the soil is loosened, grasp the green foliage near the base and pull the onion out of the ground. If the soil is particularly compacted, you can use a hand fork to carefully lift the onions out, avoiding any bruising or damage.
  • Harvest just the leaves by snipping them off with sharp pruners close to the ground. The leaves will grow back and can be harvested again. 

After harvesting, take a moment to examine your bunching onions. Look for any signs of disease or damage and set aside any onions that appear spoiled or rotten. It’s always best to discard these onions to prevent potential contamination of the rest of your harvest.

Once you’ve harvested your bunching onions, it’s important to handle them with care. If you plan to use your onions right away, you can simply rinse off any dirt or debris before using them in your favorite recipes. However, if you intend to store them, it’s best to gently brush off any loose dirt and keep in the fridge for 7-10 days.

So, don’t miss out on this opportunity to try something new in the spring or summer vegetable garden. I’d love to know if there’s a variety of bunching onion that you prefer. Share below and let us know! 

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Wednesday 13th of September 2023

It's a comprehensive and informative guide for gardeners like me. Thanks for sharing these valuable tips!

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