If you’ve heard talk of mysterious “tree onions” you may be wondering – can onions really grow on trees?! The idea of finding onion bulbs sprouting from branches seems bizarre. However there is a unique type of onion that earns the name tree onion due to its unusual growth habit.
Meet the Tree Onion
The tree onion (Allium × proliferum) is a real thing! It’s a perennial onion plant that gets its name from the way it propagates itself Rather than producing flowers like regular onions, tree onions form clusters of small bulbils at the tops of the stems These bulbils are tiny onion bulblets that can begin sprouting and growing while still attached to the parent plant.
As the bulbils swell, the stems often start to bend under their weight. When the stalks topple over and touch the ground, the bulblets will root and form new onion plants. Thus, it appears as if new onions are “walking” along or spreading through a garden, leading to other colorful names like walking onions Egyptian onions and topsetting onions.
So tree onions don’t actually grow on trees – their bulblets just tend to sprout from the top of the bending stems, giving the visual impression of a plant growing upside down!
Tree Onion Origins
Tree onions are likely native to central Asia and were spread around the globe by travelers. Their adaptability to a wide range of climates made them a useful food source to bring along.
The bulblets allow the plant to be easily propagated and shared. As settlers brought walking onions to new lands, the plants earned intriguing regional nicknames like Egyptian onions, Polish onions, top onions, and winter onions.
Tree onions are thought to be a hybrid between common onions (A. cepa) and Welsh onions (A. fistulosum). They combine the hearty, multiplying nature of Welsh onions with more bulb formation.
Growing Tree Onions
Tree onions thrive with minimal care in most temperate regions. Once established, these hardy perennials will come back year after year. A starter plant or bulbil is all you need to get your own patch going.
Here are some key tree onion growth habits:
- Tolerant of cold, heat, drought, and poor soils
- Grow 1-3 feet tall
- Form small marble-sized bulbs instead of flowers
- Bulbils sprout while still attached to the stem
- Stems topple over once bulbils are heavy, spreading the plant
- Relatively pest and disease resistant
Tree onions are supremely easy keepers in the garden. Give them full sun to part shade and some occasional watering. The bulbs multiply readily to form dense clumps and will spread steadily each year.
Harvesting Tree Onions
The real joy of growing tree onions is getting to harvest different parts of the plant throughout the season:
Spring – Harvest tender young leaves and stems when they first emerge. Use like scallions or chives.
Summer – Snip some unripened bulbils for early onion flavor. Allow remaining bulbils to fully mature on the stems.
Fall – Gather ripe bulbils once stems topple over. Use fresh or dried.
Winter – Dig up mature bulbs as needed. They store well in a cool location.
The mature underground bulbs tend to be small and elongated. Tree onion bulbs and bulbils provide a nice pungent bite and can be used cooked or raw like regular onion bulbs.
Tips for Growing Tree Onions
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Plant bulbils 1-2 inches deep in clusters for dense growth.
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Space plants 12-18 inches apart if not confined to allow for toppling.
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Allow some stalks to topple each summer to spread.
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Snip any flower stalks to encourage more bulbil growth.
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Cut back old foliage in spring to make way for new growth.
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Harvest bulbils promptly once stalks fall to prevent re-rooting in unwanted places.
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Grow in containers to control spread if desired. Miniature 1-2 inch bulbs are ideal.
Using Tree Onions
Tree onions offer home gardeners a perpetual harvest of oniony goodness! Both the bulbs and bulbils can be used in any recipe calling for regular onions. Their strong flavor stands up well to cooking.
Some tasty ways to use up your tree onion bounty:
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Sauté bulbils as a flavorful aromatic base for soups, stews, etc.
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Pickle tree onion bulbs and bulbils.
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Add chopped bulbs or bulbils to salads, salsas, guacamole, etc.
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Use green stems and leaves as a fresh garnish.
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Caramelize mature bulbs as onion side dish or topping.
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Roast bulbs and bulbils with meats, veggies, cheese, etc.
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Dehydrate mature bulbs or bulbils for storage.
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Make tree onion powder or salt.
Let your creative cooking skills run wild! Having an endless supply of tree onions makes it easy to experiment.
A Novelty with Purpose
Tree onions aren’t seen in stores because their unusual growth makes commercial production impractical. But their quirky habit of sprouting bulblets atop their stalks is exactly what makes them a fun novelty for home gardens.
Embrace the adventure of growing your own Patch of perpetually propagating onions! Tree onions are low maintenance and offer unique visual interest paired with great flavor. Let their unusual “upside down” growth brighten up your garden and kitchen.
forest gardening in Scotland and beyond
Last year was the warmest March on record: this year it has so far been the coldest. Spring ain’t what it used to be. None the less, it’s reliably time to harvest the ‘spring onions’.
I don’t mean spring onions or scallions that you buy in stores, because I don’t grow them. Let’s face it, onions are a pain to grow from seed. You need to add a lot of organic matter to the soil and weed out everything that looks too much like grass seedlings. Then, just as they are starting to look after themselves, you dig them up and eat them. By this time it’s usually August, which isn’t spring, not even here in Aberdeen.
The tree onion (Allium cepa proliferum) and the welsh onion (Allium fistulosum) are two perennial vegetables that grow well in cold weather and don’t need much care the rest of the year. They make great spring onions whenever they bloom.
Tree onion is the same species as the ordinary onion. A lot of allium species can have either flowers or tiny bulbs called bulbils in their flower heads, or both. The tree onion is one type of onion that has all bulbils. These often sprout when they’re still on the plant, giving it a tree-like appearance. One of the many names for this plant is “walking onion,” because the stem usually falls over as the bulbils grow roots. This makes the plant “walk” around the garden. It also reproduces by bulb division underground, like a shallot or a daffodil.
This gives two ways to exploit tree onions for spring onions. First, you can dig up the parent plant in the spring when it sprouts new shoots, separate some of the bulbs, and plant the rest of them. If you wait until later in the year to get the bulbils, you can plant them in a bed and watch them grow into very well-shaped spring onions. This plant is also known as a “topset onion,” and it’s kind of like having a free supply of onion sets for spring onions. You can let them grow into bulb onions, but they don’t get very big. ). They are very hardy, so you can plant some in the fall for spring growth. They will also keep well if you store them somewhere cool and dry, so you can make successional sowings later in the year.
Welsh onion is a different species from regular onion but it’s very similar to tree onion. It doesn’t make bulbils, but a fleshy flower head that can be used as a flavoring or left to grow into seeds (picking the flowers stops the plants from making seeds and puts their energy back into making bulbs). Like tree onions, they split underground, but in March and April, you can lift them up and split them like spring onions.
Both species can also be harvested by picking leaves in the summer. When I divide a Welsh onion, the spring onions are bigger and more uniform in size. On the other hand, tree onions are better for leaves, in part because the bulbils can be used to make a really dense patch. The best use is probably for Welsh onions to divide in the spring and tree onions for their leaves and sets to grow on. If you allow welsh onions to flower you will be very popular with the bees.
Real spring onions can be used in all the same ways that you would use the seed-grown ones. Spring onion sambar is my favorite. To make it, you fry a bunch of whole spring onions until they get soft, then add tamarind, coconut, and spices to make a sauce, and let it cook for a few minutes. It’s a great way to forget the sleet driving at the window. Search for: 87646.
The 2 Most Important Tips for Growing Big Onions
FAQ
Where do onions grow?
What causes onions to grow?
What is the name of the onion tree?
How to plant tree onions?
What’s more, the soil is peat-free and sustainably produced. Mix 30% sand into the soil to make the substrate mixture less nutrient rich; this also ensures better water drainage. The best time to plant tree onions is in late summer from August onwards.
Do tree onions grow underground?
The tree onion ( Allium x proliferum or Allium cepa var. viviparum) is curious looking: The small bulbs do not form underground, but rather above ground directly on the stalks, forming several tiers. But this is not just an attractive onion, it is also delicious and most parts of the plant can be enjoyed nearly all year round.
How do onions grow?
After the vegetative growth stage, the onion plant enters a phase known as bulb development. During this stage, the plant initiates the formation of its bulb, a part of the onion we use in the kitchen. As the plant continues to grow leaves, the bulb also starts to take shape. The leaves and bulb grow in tandem, complementing each other’s progress.
What is a tree onion?
Tree onions are also known as topsetting onions, walking onions, or Egyptian onions. Genomic evidence has conclusively shown that they are a diploid hybrid of the shallot and the Welsh onion (A. fistulosum). [ 2 ][ 3 ][ 4 ] However, some sources may still treat the tree onion as A. cepa var. proliferum or A. cepa Proliferum Group.