Potato Onions

Potato onions are extremely old perennial heirloom onions.  They are an edible onion that is undemanding to grow and reasonably productive.  For a number of reasons they are quite rare in Australia at the moment and have been close to local extinction.  Hopefully they start to gain popularity again soon.

What are potato onions

Potato onions are a type of bulb onion, they have nothing to do with potatoes whatsoever.  They are called potato onions because they multiply under the ground, kind of like how a potato will multiply under the ground if it is planted.  Potato onions taste, look, and grow like regular onions.  I have always had a soft spot in my heart for the potato onion, I don't know why, I have just always liked them.

They do not often flower and these flowers rarely set viable seed, instead they reproduce by dividing the underground bulb.  If well looked after, each bulb can split into a nest of anywhere between 3 and 15 new bulbs in a season!  Apparently they were very commonly grown in the 1800's but like so many heirloom vegetables no one knows who bred them or exactly how ancient they are.  I have heard that there used to be many varieties and different colours of potato onions around, this number has unfortunately dwindled to about two varieties (one white, one brown) currently in Australia.  The brown potato onions are rare and difficult to find, but they are far more common than the white variety at the moment.  I don't understand why this is as the white ones look nice and seem to reproduce slightly faster than the brown.

Potato onions were fairly common when I was a child, at least in rural areas.  I never remember seeing any for sale anywhere back then, but everyone seemed to grow them at home.  Because the bulbs are relatively small for an onion and divide erratically producing inconsistent sized/shaped/numbers of bulbs they are not suited to mechanical harvest.  While this makes them unsuited to mechanical harvest or mass production, it is a trait that is very welcome to home gardeners, permaculturalists and people who are becoming increasingly self-sufficient. 

Being perennial and only reproducing by division means that you do not need to worry about maintaining pure lines, preventing cross pollination, growing enough to prevent inbreeding depression (a big problem in onions), rouging out undesirable plants, maintaining a seed bank (allium seed normally only lasts a year so needs to be replaced constantly), locking up land to grow out plants to produce seed, and so on.  It also means that you can easily work out how many you need to grow to always have a supply of onions as well as enough to replant the following year.


Where I got my potato onions

When I was a child everyone grew potato onions, I had thousands of them and never thought too much of it.  When I grew up and left home I left them behind and they were lost or eaten by animals or something.  After I got married and had a small vegetable plot I tried to track them down but nowhere sold them.  I asked the people who still live around where I grew up, apparently potato onions are nothing but a distant memory in those parts and the people who gave me my first ones have long since died. 

I eventually found that Diggers sold them and everywhere else was out of them.  Like a lot of other people I have had trouble with Diggers so did not want to buy from them.  For a few years I resisted the temptation to buy them and waited for another place to buy from but eventually, against my wife's sound advice, I went ahead and ordered some potato onions from Diggers.  When they arrived most of the bulbs were shriveled and dead, the few living bulbs were covered in mould.  I ended up only getting two plants to sprout.  Those two plants grew weakly throughout the year without dividing and then died.  I carefully dug one plant up to see if there was a bulb in the soil and there was nothing.  I left the other in the hope that something would sprout the following year, but nothing came of it.  Upon telling Diggers that the potato onions did not do well I was told that it must have been my fault for growing them wrong, and that the bulbs were end of season so not all were healthy and it was my fault as I should have expected that.  I have learned my lesson - I wont bother buying anything from Diggers again.

I eventually tracked down a private grower who had a handful of potato onion bulbs that he was growing and eating each year, he said that the previous season was harsh and he was not sure if they were still alive.  I appreciated his honesty and traded some things for these questionable bulbs, when they turned up many were shriveled and dead but some were still healthy and looked good.  Each of them grew well and divided the first year.  Each year after that all of the potato onions have fared very well for me except last summer when it was extremely hot and dry.  Even though last year was terrible they still did ok, they did not increase in number, they all grew small, and some did not survive, but I still have enough to grow on to build numbers up again.

How are potato onions used

The top green parts of potato onions are rather delicate and can be used instead of spring onions or chives.  They are never tough or fibrous, and generally look pretty nice.  Around here they never get overly tall, 10 to 20 cm is the tallest I have seen the tops.  If one was to grow an ornamental garden potato onions would not be out of place in the front border instead of something like mondo grass, plus they have the bonus of being edible.  They also have the added advantage of growing most of the year, but then dying back for harvest when times get too dry and hot, this makes them pretty water efficient.  Frosts do not seem to bother them in the slightest.

While the tops are eaten, the underground onion bulbs are the important crop here.  They can be used in any recipe just like regular onions.  They are smaller than many onions which means that you never have half an onion left over to work out what to do with.  They are said to store for well over 12 months, but I am pretty sure that depends on the climate and the way in which you store them.  The longer they are stored, the stronger they taste.  Being so strong a little onion often goes a long way.

How to grow potato onions

Potato onions seem to grow like pretty much any other onion, except instead of messing about with fiddly seedlings every year and keeping some to go to seed, you simply plant a small bulb.  Each bulb that you plant will grow into a nest of potato onions, the number will vary from 2 or 3 to well above 15.  In my climate they generally produce 5, but this does vary a lot for no apparent reason.

Tradition dictates that potato onions are planted on the shortest day of the year (around June 21) and harvested on the longest day (around December 21), to be honest I think this only matters in some climates.  I plant my potato onions in mid Autumn when things start to cool down and I have garden space available, I have also heard of people planting in Spring with good results.  Sometimes I do not dig them up at all and just let them grow whenever they feel the urge, or after digging them up I replant some then and there to let them do their thing when they feel the time is right.  They seem pretty adaptable to whatever I throw at them.

We normally plant potato onions about 10 or 15cm apart, larger distances between plants would possibly result in larger onions but we do not have enough space and water is scarce here so everything is planted closer than optimal.  Just like all of the Alliums, they prefer a slightly alkaline soil but will grow in a neutral soil.  The more fertile the soil the better result you will obtain from them, just be careful not to have too much nitrogen in the soil otherwise you will get a lot of top growth at the expense of the bulbs.

We harvest when the tops dry off, then it is quite simple to pull them out of the soil and put them somewhere safe in the garage to dry off a little more.  After a few weeks I brush off the soil and they are ready to be put wherever it is that you store your onions.  Just like any other type of onion you do not have to dry them unless you plan to store them, you can dig them up to use whenever they are needed.

I have read in old books that you always plant a mix of different sized bulbs.  They say that small bulbs will grow and divide into a few large bulbs, and a large bulb will grow and divide into a whole bunch of small bulbs.  I always keep a range of sized bulbs to replant.  I am not sure if it makes any difference anymore, I have a feeling that those days are gone.  I also keep two varieties of potato onions, one brown and one white, and I find that each variety will grow better in some years than the other.  If I ever find any other varieties of potato onion I would love to grow them too.  Interestingly the white potato onion has become locally extinct in most countries in the world and only a handful of people are keeping it in Australia.  I would hate for either variety to disappear from Australia which is all the more reason to grow them both.

Becoming more self sufficient

The important part about potato onions is not to eat them all.  Ever!  In this way you will have them producing food for you forever.

As long as you always keep some to plant after harvest you should have potato onions for the rest of your life.  There is nothing more self sufficient than to dig up a potato onion nest for dinner, take some for eating, some for storage to eat later, and replant one into the very same hole you just dug them all out from.  This can go on potentially for the rest of your life and you would never run out of potato onions or need to get new ones from anywhere.  This is a good lesson to teach the kids, even if you are not explicitly teaching them they will still notice the attitude of taking only what you need as well as preparing for the future.

Having a great storage ability means that you never have to worry about what to do with the excess.  You either store them somewhere dry for later, or you plant them which is essentially storing them in the soil for later.  There is no need to run out of onions anymore.  We grow our vegetables without the use of poisons both "organic" or synthetic, in this way we gain a little more control over what we are eating.


Comparing potato onions with other types of culinary onions

Regular bulb onions are larger than potato onions.  This sounds great but usually ends in wasted onion as they are too large for whatever meal they were intended for.  Potato onions are small, while this lack of size causes you to spend slightly longer in peeling it does mean that you always have just the right amount of onion for the dish.  If you need more onion for the meal, you simply use more onions.  Regular onions are grown from seed and are biennial, requiring a long time to produce seed.  Potato onions reproduce through division of the bulb, they will do this efficiently each year.  Potato onions also grow a bit smaller and can fit into small spaces in the garden easily  This means that potato onions are relatively easier to grow year after year and take up little space.

Spring onions grow a larger and tougher leaf compared to the delicate foliage of the potato onion.  I prefer to eat the foliage of the potato onion to the spring onions as they are thinner and less fibrous.  While I do have some spring onions growing we tend to use the Everlasting onions more as we have more of them and they are a bit nicer to eat.  Everlasting onions are a perennial onion that we use in place of spring onions.  They also divide underground and will grow a small bulb that is much the same as a French Shallot.  Potato onions tend to divide a bit differently than everlasting onions, and grow more delicate foliage.  The bulbs taste a bit different, the potato onions taste more like a regular bulb onion and the everlasting onions taste more like a French shallot.  Overall they can be substituted for each other in meals but will give a slightly different result. 

French shallots and potato onions are essentially different strains of the same thing.  They taste and look a bit different, but can be easily substituted for each other.  Keep in mind that a small yellow cherry tomato and a large red beefsteak slicing tomato are essentially two different strains of the same thing, or a pug dog and an irish wolf hound are different strains of the same thing.  They can all be used interchangeably, but the results will differ slightly.  The French shallots have a milder taste, they do not store anywhere near as well as potato onions, and they do not divide as much as potato onions, but they tend to be slightly larger than potato onions.  I do like French shallots, but again we tend to use the Everlasting onions in their place.

Tree onions and potato onions are similar in that each will grow a small underground bulb that divides each year.  Tree onions grow a bit larger, and their foliage is taller and lot more rough, and they tend to divide less than potato onions.  Tree onions will send up a flower stalk and will grow small onion bulbs on this stalk instead of seed or flowers.  Potato onions tend not to flower, and if they do generally nothing much comes of it.  From what we have seen the tree onions tend to be hardier than potato onions and yield a more consistent crop despite the harsh climate.

Breeding new types of potato onions

Potato onions rarely flower, if they do flower very few viable seeds are produced.  Any resultant seedlings are said to display great genetic diversity and are meant to mostly grow very vigorously.  While you will not be able to eat the onion when it is flowering as it will become tough, it is worth it.  If any of the seeds are fertile they will grow into a new variety of potato onion, and from what I have heard the new type is far larger and healthier than the parent stock.  The onion bulb will not die after flowering so can be planted and grown on the following year, so if they do flower you have not lost much and you have a lot to gain.

I am trying my best to convince my potato onions to flower and try to get a few seeds out of them, so far they are reasonably unwilling but I have a couple of ideas that may help in the future.  For the first time ever I have a potato onion flowering this year.  The other potato onions are bit behind in growth to this one so there is a chance that some more may flower too.  I am extremely excited over this!

My first ever potato onion flower!  Not a large nest of potato onions after last year's heat

Even though my potato onions can flower there is no guarantee that they are able to produce viable seed.  If they are able to produce viable seed there is also a chance that something will happen to the flower this year so that I will not find out for another year or so.  As this is the first potato onion flower I have ever seen my anxiety levels are high, perhaps too high for something such as an onion.

There is some small scale potato onion breeding work going on overseas with someone who has made potato onions flower and set a small amount of seed.  His breeding notes are very comprehensive and can be read here: https://docs.google.com/document/d/1jnqst7-9YfWFovhqjARtcZZVJC0TPzKsow_5mdAwnyA/edit

While I am not currently producing potato onion seed, I do hope to do so in the future.  If the Australian strains of potato onions are never going to set viable seed, which is not unlikely, a small number of true potato onion seeds were imported into Australia and I have been in contact with one of the lucky few who were able to purchase them.  If all goes well hopefully one day I will be able to get hold of a few of the seeds or bulbs from the seed grown plants.

If I have extra bulbs I do sell potato onions, both brown and the much rarer white, on my for sale page.  Unfortunately I will not have any for sale in 2013 but I am building up their numbers as best I can in the hope to be able to offer them again next year.