Ultimate Guide to Growing Bunching Onions in Container

Although inexpensive, bunching onions topped the grocery list a few months back whenever I stepped out to buy fresh veggies every week.

With reaching my doorstep, my savings for pocket money vanishes. So I desperately needed to find a way out for this.

When I returned from a trip to Wales last summer, I had a few pieces of advice from my uncle about growing a teeny-tiny onion garden here in Minnesota.

For growing bunching onions in containers, procure 6-12 inches deep plastic, terracotta, ceramic pots or a large seed tray with drainage holes. Plant the seeds about 1/4th inch deep and 1 inch apart in groups in well-draining soil and thin the seedlings once they reach 3-4 inches high.

Image represents growing bunching onions in containers
Different pots are good for growing bunching onions, like plastic, terracotta, clay, and even ceramic pots.

From the start of my gardening journey, I wanted to grow bunching onions in a comfy spot, as my uncle made it easy.

Fortunately, all my effort paid off in setting up a small garden using pots, and I learned a few precautions while growing them along the way.

Stand by to learn growing bunching onions in containers and follow some tips about caring for them properly.

Reasons to Grow Bunching Onions in Containers

Containers like ceramic, terracotta, and plastic pots are great options for growing bunching onions.

You can also grow the bunching onions in garden beds, where they will sprout in a bunch and multiply to form clumps.

Containers are preferable as bunching onions have a delicate, thin, and fibrous root system that cannot spread to greater depths under the soil.

;Image shows thin root system of bunching onions
Bunching onions have a thin and delicate root system that cannot enter deep inside the soil.

Without a proper root reach, they cannot get their root hairs on water and minerals.

Here are some additional favors you can bring out for growing bunching onions in containers.

  • The small area in the containers helps hold the nutrients in the soil so that the short roots of onions can easily grab them.
  • Estimating the amount of water and fertilizer is easy in small planters than in the open ground.
  • Bunching onions are perennials that beget new leaves each season, so harvesting them from a small patch rather than garden-fresh is painless.
  • Bunching onions refrain from forming large underground bulbs like other onion varieties. So, they rarely require wide belowground soil space.

So, shallow containers are fine as long as they have drainage holes at the bottom.

What is the Best Time to Grow Bunching Onions?

Bunching onions can show feasible growth when germinated directly from the seeds.

But you can also plant these onions individually by separating single onion plants from clumps after they mature.

Planting onion stem divisions has no fixed season, but winter (December-January) is the supreme time to cultivate them for prolonged harvest in later seasons.

Image represents the placement of bunching onion divisions indoors in winter
Start bunching onion seeds indoors in pots in winter and transplant them later in warm soil.

If you decide to grow bunching onions from seeds, you may harvest them in late spring to early summer (May-June) after the flowers fade to brown.

My uncle used to sow the seeds in early spring to harvest them at the National Eisteddfod Festival in summer for a family feast.

However, you can also plant the seeds in late summer to get garden-fresh bunching onions as fall or spring comes by.

Another way is to start the seeds indoors mid to late winter (5-6 weeks before the last frost).

This way, onions can have long-lasting foliar growth after transplanting them outdoors in spring (March). 

How Long do Bunching Onions Take to Grow?

Bunching onions are speedy perennials that catch up with their growth only a few days after germination.

Since people grow bunching onions solely for their foliage, it’s a matter of time before deciding when to harvest them.

Germination may initiate around 1-2 weeks on warm and well-draining soil saturated with moisture.

Image represents the seedlings of bunching onions in a starter tray
Bunching onions can readily germinate with the right soil temperature and humidity levels.

It may take 2-4 months to see harvestable onion clumps in your garden.

If you consider starting the seeds early in winter, you can see them on time in spring after a few months.

However, to encourage onion growth, you can cut their foliage after they reach about 30 centimeters.

They will quickly recover and retain new foliage in 1-3 weeks.

This is great if you are scouring your garden to refill your kitchen inventory with fresh veggies!

Bunching onions are speedy perennial veggies but do you know there are also other slow growing plants that can suit your house interior?

Requirements For Growing Bunching Onions in Containers

Growing bunching onions in containers is a satisfactory job that you will feel during the harvest.

You can grow as many onion clumps as possible, but the containers must be spacious enough for the roots to roam freely under the soil.

Likewise, the substrate must be a blend of the correct and appropriate amount of components.

So, let’s get into the requirements for growing bunching onions.

Best Container

For outstanding crop growth, choose pliant containers for the onions.

Several alternatives include clay, terracotta, plastic, and even ceramic pots.

Image represents the terracotta pots for growing bunching onions
Terracotta pots are also fine for growing bunching onions as long as they have drainage holes in the bottom and a considerable width.

My uncle made his own garden bed by nailing some wooden planks to grow these onions, and it worked!

But, the containers must be around 6-12 inches deep with a fair number of drainage holes and considerable brim width.

Some containers have a single large hole at the base, which is also fine as long as the water stays ample in the soil.

Check the table to get an idea of containers you can use to grow bunching onions.  

ContainersSpecifications
Caribbean Plastic PlantersLight weight with considerable brim width

Drainage holes with detachable plug

Dimensions: 8.25"×8.25"×6.75"
Terracotta PotsDrainage holes with saucers at the base

Lightweight but sturdy

Dimensions: 6.5"×6.5"×6.5"
Sunnydaze Ceramic PotsStrong and durable with glazed finish

Frost-proof and with a drainage hole at the base

Dimensions: 11.75"×6"×9.5"
Seed Starter TrayExtra cup space for larger seedlings

Comes with a humidity dome to preserve the humidity for germinating seeds

Drainage hole present at the bottom of each cup
Flexible Plant Nursery PotsFlexible pots with spacious depth for root growth

Ample amount of drainage holes at the bottom

Dimensions: 6.7"×5.1"×6.9"

Best Soil

Bunching onions have a fragile root system, so they require nurturing of proper soil.

Use a well-draining, loamy, organically rich, and water-retaining soil low in pH (between 5.5 and 7).

Image represents the soil used for growing bunching onions
Bunching onions prefer well-draining, moisture-retentive, and organically rich soil.

The soil must also be fluffy so the roots can willingly grow without hindrance.

You can DIY your own potting mix recipe by blending some household bits.

Grab one part compost (cow dung), two parts normal garden soil, 3 parts sand, and 3 parts filler (decayed veggies, coffee grounds, or coconut fiber) and blend them in a container.

Add water to mix it thoroughly so that the mixture stays evenly moist.

This common household compost works in most vegetable gardens, including bunching onions.

If you don’t want to risk your precious harvest, you can buy a trusty, readymade seed starter mix for your plants.

Check the table below for an idea about some commercial starter mix for the onions.

Seed Starting MixesSpecifications
Sun Gro Horticultural Seed StarterContains a mix of peat moss, perlite, dolomite lime, and organic agent
Espoma Organic Seed Starter MixContains a supreme blend of peat moss, perlite, yucca extract, and lime

Also has ecto and endo-mycorrhizae for root growth
Premier Horticulture Organic Pro Seed StarterContains coconut fiber for optimal root growth and rot protection

Slow release of amended nutrients
Miracle-Gro Seed Starting Potting MixEasy to root cuttings from leaves, stems, and bulbs

Easy to start the seedlings for most veggies
Purple Cow Organic Seed StarterRapid induction of germination

Extra cow compost for faster germination

Growing Bunching Onions in Containers

You can grow bunching onions in containers through seeds or stem divisions.

Both methods are easy and reliable, ensuring fresh onions every season.

1. Growing Bunching Onions from Seeds

You can purchase the seeds from an online or a nearby store. They may be labeled as “scallion seeds” in your area.

Another choice is to harvest fresh seeds from the plants. You can do it if you have a beautiful patch of flowering bunching onions.

Tips for Harvesting the Bunching Onion Seeds

To collect the seeds, you can follow these simple steps.

  • Wait for the flowers to dry up (from late spring to early summer).
  • The flower heads turn brown and papery, with black, shield-shaped seeds peeping from the top.
  • Using clean pruners, cut the flower heads individually from the base and keep them inside a paper envelope.
  • Shake the envelope to release the seeds and separate them from the husk.
  • Keep the seeds in a clean, dry, labeled paper envelope until sowing.
Image represents the dried flowers of bunching onions
Extract the seeds from bunching onion flowers after the ivory-white flower heads turn brown and fade.

Sowing Bunching Onion Seeds

Mid to late winter is the perfect time to sow bunching onion seeds.

It aids in the early establishment of the seedlings and hardens their roots during transplanting in spring.

You can follow these tips when the right time approaches to sow the seeds.

  • Wear protection like gloves and take pots or a seed tray around 6-12 inches deep.
  • If you are going with pots, take one with enough width to cram up a few plants easily.
  • Fill the pots or trays with the readymade potting soil or fill it with a common starter mix.
  • Jam enough potting mix in the chosen containers up to an inch below the rim.
  • Using chopsticks, dig up about 1/4th inch deep holes at a distance of 1 inch apart.
Image shows the process of sowing the seeds of bunching onions
Bunching onion seeds require humidity, proper soil depth, temperature, and plenty of moisture to germinate right on time.
  • Place enough holes in the soil as much as available space in the container.
  • You can plant about 3-5 seeds in each hole and cover lightly with soil.
  • If you use trays, place 2-3 onion seeds per cup.
  • Moist the soil fairly with water and place the containers over a heating pad maintained at a temperature of around 15-20°C.
  • Cover the containers with plastic wrap to maintain a warm and humid environment.
  • Locate the set-up near an east-facing window.
  • Keep on misting the seeds faintly with water whenever the soil feels dry to the touch.

It will take the seeds about 1-2 weeks to germinate.

Give them 4-6 hours of daily sunlight once the seedlings begin to sprout.

You can also grow the plants directly in the ground after winter. To do this, place 3-5 seeds in each hole about 9 inches apart or sow individual seeds in each hole about 4-6 inches apart.

After the seedlings sprout new leaves and become 3-4 inches tall, transplant them into the garden soil.

You can check the video below to revise the process of planting and growing bunching onions from seeds.

Transplanting the Seedlings

Bunching onions require transplanting to halt the danger of root crowding in planters.

With each growth, bunching onions require slightly wide space for their roots to roam freely in the soil.

So, it is better to transplant the seedlings in a wide area in your garden than to let them suffocate when they reach the seedling stage.

The best time to transplant the onion seedlings is post-winter when the ground becomes warm.

Aim for the spring to transplant and give frequent checks using a thermometer for the soil temperature to normalize.

You can begin transplanting when the ground temperature reaches around 15-20°C.

  • Choose a sunny place in the garden with 4-6 hours of direct sunshine.
  • Border a required garden patch using wooden planks and amend the area with the homemade mix up to a foot depth.
  • Prepare rows of soil about 9 inches apart using a trowel.
  • Gently uproot the seedlings from the containers and transplant them along the row length. 
Image represents transplanting the seedlings of bunching onions in ground
Transplant the seedlings of bunching onions along the row length on open and warm ground in spring.
  • Firm the soil around the onion roots to hold the seedlings in their place.
  • The seedlings need to be 4-6 inches apart in each row.
  • Apply a thick layer of mulch at the topsoil to suppress the weed growth around the seedlings.
  • Water the seedlings when the soil is dry, and harvest after the foliage reaches about a foot long.

You can also cut the top leaves of the seedlings when they reach about 3-4 inches tall.

After this, the seedlings will focus their energy on showing rapid root development rather than using their energy for foliar growth.

2. Growing Bunching Onions from Divisions

You can start a new bunching onion batch by planting onions from their divisions.

For this, buy a fresh bunch of onions from the market or take some from your harvest.

Here are the following steps for dividing and replanting your bunching onions.

  • Choose the right time in spring or summer when the leaves are about a foot long.
  • Uproot the onion clumps with your hand and separate the onion plants at the root ends.
  • Replant it in the same manner as you do for the seedlings, ensuring a sufficient distance between the mature plants.
Image shows fresh harvest of bunching onions
You can separate individual bunching onion plants from the clump and replant them as divisions.
  • While replanting, you can also cut the leaves from the top of the mature plants to initiate speedy root growth.
  • Dividing and replanting will be easy if the seedlings are 3-4 inches tall, as the roots can easily catch up with the growth.
  • Water the plants after the transplant to evenly moisten their roots.
  • Also, apply some more mulch to cover the topsoil.

Harvesting Bunching Onions

Harvesting the bunching onions is a pretty easy trick; even novice gardeners can do it.

The plants can be harvested when the leaves mature to a foot length and flop over the ground.

You can learn the harvesting time of the bunching onion if leaves become slender and later arch and flop over on the ground. Besides, 

3/4th of the plant leaves turn bright green with a darker hue at the leaf tips when the onion meets the harvesting period. 

Or watch the lower parts of the leaves attain a light green coloration or learn it through the strong oniony aroma scenting from the leaves. 

Image represents harvested bunch of bunching onions
The best time to harvest the bunching onions is when their leaves become a foot long.

Also, keep an eye on the signs that the plants exhibit when they’re ready.

You can follow the steps below to ensure a successful harvest.

  • Choose an onion clump having green tops and white stalks.
  • Dig from the bottom using a trowel and pull out the whole clump.
  • Dust off the soil from the roots by breaking the soil lumps. Use hands if necessary.
  • Be gentle not to harm the roots in the process.
  • You can also trim off the leafy foliage up to the stalk’s length from an individual plant.
  • After harvest, place the onions in a tray and wash under the sink water to remove the attached soil.
  • Finally, you can refrigerate the onions or use them fresh on any dish you prepare.

Tips to Care for Bunching Onions

Bunching onions may seem delicate, but they are hardy and drought-tolerant.

Although these herbs show slow growth in winter, they rapidly fill your garden patch or pots in spring or summer.

However, you can ensure a healthier harvest with minimal care from seedling to maturity.

  • Place the bunching onion seedlings in a spot receiving 4-6 hours of direct light indoors, such as a south-facing window.
  • You can also choose an east-facing window, but move them to a sunny window in the afternoon.
  • Use 0.016 liters of water for each plant in a clump. Apply water to evenly moist the soil up to the whole depth.
  • Consider watering next time when the soil dries up to an index finger knuckle depth by giving a “finger depth test.”
  • Sustain the soil pH around 5.5-7, as onions thrive in acidic soil.
  • Start feeding the plants with a high-nitrogen liquid fertilizer about three weeks after planting.
  • Continue the application once every 2-3 weeks and avoid feeding the plants a month before harvest.
Image represents the process of covering the topsoil with leaf mulch in winter
Mulching the bunching onions at the topsoil with leaves helps to protect their roots in winter.
  • In winter, place a layer of straw or leaf mulch over the topsoil to warm up the roots. Remove it once the temperature becomes feasible in spring or summer.
  • Manually remove unwanted weeds from the pots, trays, or garden patches.
  • Use a weak jet of water to wash the leaves of growing onions once every 2-3 weeks in the morning until harvest to keep out the pests or pathogen spores.
  • Invest in Pyrethrin to deter any obvious pest or disease infestation, with instructions per pack.
  • If the tips of the onion leaves turn brown or yellow, trim them at any season using clean pruners.

You can also continue growing the bunching onions indoors following their germination under grow lights for 10-12 hours daily in winter until spring arrives.

Conclusion

Growing bunching onions in containers is a satisfying job for farmers and gardeners.

But, the task is easy, fun, and workable even for newbies. Anyone can dip their toes in gardening by growing these onions.

Choose the right container with considerable depth and drainage holes, and proffer the seedlings with nurturing of proper soil.

Give the correct care after the seeds germinate and keep the plants in a sunny spot.

Like bunching onion, lettuce is a mellow green veggie that can comfortably suit itself in small pots. So, what’s the wait for a nutritious salad bowl this season?

May your garden be full of fresh oniony aroma year round!

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