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Growing Bunching Onions

Bunching onions are very popular and can be expensive to buy. Fortunately, they are easy to grow and take up very little space in the garden.

Growing bunching onions

Growing bunching onions

Why Are They Called Bunching Onions

Small onions, baby onions, green onions and spring onions are terms that make some sense, but would anyone call them bunching onions? One explanation is that they are sold in bunches. Another is that you can grow the seed close together, in a bunch, to prevent bulbs from forming.

The naming of onions is very confusing, in part because common names are local. A green onion in the US is not the same as a green onion in England or Australia. I just bought some bunching onion seed called Southport White Globe – Green Bunching Strain from Stokes, an American/Canadian company. A little online research indicates that this is not a bunching onion. It is actually Allium cepa, an onion that will form a bulb (1).

The true bunching onion is Allium fistulosum, a perennial that does not form a bulb.

Provided Allium cepa is harvested early enough it will give you a green bunching onion. The bunching onions sold in most grocery stores in North America are a form of Allium cepa.

Growing From Seed

Bunching onions are easy to germinate from seed. Plant just under the surface of the soil and wait a few weeks. The seedlings will look a lot like grass so make sure your garden is grass free before planting or you won’t know which are plants and which are weeds.

Keep them well watered, and side dress with compost or fertilizer. The roots are fairly shallow and don’t like to dry out.

Succession planting makes a lot of sense. Plant more seeds every 3-4 weeks to have a continual supply of onions.

You can harvest onions at any time – don’t wait until they are mature. Pull the complete onion, or cut off the leaves and leave the bulb. The bulb will form new leaves which can then be harvested again in a few weeks. My wife prefers the bulb so she harvests the complete plant by pulling the most crowded ones to give the rest more room to grow.

Start Early Indoors

Bunching onion seedlings ready for planting

Bunching onion seedlings ready for planting

For a really long harvest consider planting some seeds indoors about 5 weeks before they can be put outside. The seeds can be sown quite thick, in community pots. When it is time to plant outside, dump the community pot out, separate the seedlings and plant each little plantlet in its own hole. These will be ready to harvest much sooner than seed sown directly in the garden.

 

Growing From Sets

You can also grow bunching onions from sets which are the small onions sold in nurseries in spring. Any variety will work. The key is to harvest them before they start expanding the bulb. This is especially true if you like the top green leaves which you can harvest all summer long.

Perennial Bunching Onions

Allium fistulosum, by Robert Pavlis

Allium fistulosum, by Robert Pavlis

Allium fistulosum, the Welsh onion, is a perennial that makes a very nice addition to the perennial bed. These bulbs easily overwinter in zone 5 and start growing early in spring. The leaves can be harvested all summer long.

The seed from these plants is easy to collect and can be sown in either fall or spring, to produce more plants. The younger plants can be harvested whole if you like to eat the lower bulb part. The advantage of using this species is that they can be sown in fall, which produces very early spring bunching onions.

A mature Welsh onion does not form a large bulb, but it does divide over time forming large clumps. These can be easily divided in spring to make more plants.

To find out more about this onion have a look at my post; Allium fistulosum

General Culture

Onions are sallow rooted plants and don’t like to dry out, so keep them well watered and mulched.

They are also heavy feeders so side dress with compost or fertilizer, depending on what your soil needs. Remember you are replacing missing nutrients in your soil, and not feeding your plants.

Succession Planting

Bunching onions grow fairly quickly and even in zone 5 they don’t need the whole summer to grow to eating stage. The most productive way to use your space is to plant a few every 3-4 weeks. This will give you a constant supply of onions.

Succession planting works well with seeds and sets. If you buy a bag of sets and don’t use them all at one time, put the remaining ones into the fridge so they don’t start to grow.

Harvesting

The key to harvesting is to start as soon as they are big enough to eat. If you are pulling complete plants, pull the most crowded ones each time you harvest which gives the remaining ones more space to grow.

Two parts of the plant can be eaten; the bulb and the top green leaves. If you prefer the bulb then harvest complete plants. If you prefer the leaves you can simply cut the leaves off and the remaining bulb will grow new leaves. This can be very productive – but most people like the tender bulbs.

References:

  1. Heirloom Onion Varieties; http://www.motherearthnews.com/organic-gardening/heirloom-onion-varieties-zewz1308zpit
  2. Green Bunching Onions; http://horticulture.oregonstate.edu/content/onions-green-bunching
  3. Photo Source for bunching onions: Green Mountain Girls Farm

 

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Robert Pavlis
Editor of GardenFundamentals.com

I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes–I am a plantaholic!


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