Experimental Homestead

Mr. Wintertons Remarkable Potato Onion!



This past Spring Kelly Winterton of Utah, an amateur gardener turned onion breeder, generously sent me 8 bulbs of his new Potato Onion the Green Mountain Multiplier.  This newly introduced variety was grown by Mr. Winterton from seeds of the Yellow Potato Onion.  Potato Onions don’t go to seed very often, but some years back his did go to seed and he was adventurous enough to plant the seeds to see what would happen; what happened was new larger Potato Onions in several different colors.  The Green Mountain was the first to be shared out to other people.  Most of the others are still under selection and propagation with one new White variety being offered this year.

Kelly has said that every new variety he is growing from the seeds of the Yellow Potato Onion have been larger than the parent.  He thinks the greater size of the new onions may be due to freedom from virus that the Yellow Potato Onion has picked up over it’s very long career.  Since Potato Onions are grown from divisions instead of seed, it seems plausible that they could accumulate virus.  Plants grown out from seed apparently do not carry on viral infections of the parents, so growing from seed would be a way to potentially “cleanse” the Potato Onion occasionally.   The other method I know of is to heat the plants until the virus dies, sort of a fever.  I’m not sure if the fever technique would work for an onion, but it is used on fruit trees.  The viral theory seems plausible, but whatever the case, the onions are truly large for potato onions.

When I received the bulbs in spring, they were very firm and did not look like they had suffered in storage over winter in the least.  I grew them out as usual without any overly special coddling.  The largest specimens are over three inches in diameter, and there are quite a few pretty large ones.  The Smallest one is one and one eighth inches.  Coincidentally, I also have the largest Yellow Potato Onions I’ve ever grown this year, but out of a pretty big crop, none are quite as large as the Green Mountains.  My larger than usual Yellow Potato Onions are due for the most part to my deliberate planting out of the smallest onions from last year’s crop which makes for fewer, but larger onions.

largest and smallest

Results are somewhat preliminary as this is the first year, but the Green Mountain Multiplier also seems to be somewhat more consolidated under the skin than the Yellows.  To explain, the Potato Onion is made up of many “eyes” or points of growth which can be seen if the onion is sliced crosswise.  Each eye is a growing point and can sort of be seen as it’s own plant or division each of which will grow into a new onion also with a number of eyes.  Often, papery divisions will develop in the onion, especially in storage making each onion composed of several which can sometimes be divided before planting.  Thats fine, but it can be a hassle when cutting the onions for cooking purposes because the papery divisions have to be removed.  My early impression when the original bulbs arrived, and were planted, and again at harvesting is that the Green Mountain bulbs have fewer of these papery divisions.  That is a good thing in terms of processing them in the kitchen, and not likely to be a problem for planting.

My Potato Onions have produced seed this year as well, and I’m excited to plant some of them to see what I come up with.  Typically though, reluctance to send up flowers at all is one of the Yellow Potato Onions best known traits.  For instance, I have been growing them for over 10 years and have only seen them flower one other time.  Kelly thought it might be a good idea if the onions produced seed more often so that they could occasionally be purged of virus.  I’m inclined to think that it would be better to retain the Potato Onion’s reluctance to produce flowers and learn to induce flowering when we want it.  As I said in edits to my previous post about Potato Onions, I was trying to get mine to seed this year.  How much of them going to seed had to do with my attempts at forcing them, and how much to do with some other serendipity, I don’t know, but I think that if they do it but rarely, we ought to be able to make them do it more frequently by some sort of manipulation.  Anyway, this is all a segue to say that while a number of my Yellow Potato Onions went to seed this year, the Green Mountain Multiplier did not.  More growing seasons will be required to see just how the seeding (or lack of) trait plays out in the Green Mountian Multipliers.

Midseason growth of a larger bulb.  Large bulbs produce more smaller bulbs as a rule.

Of the 8 bulbs Kelly sent me, all survived well and I now have 56 onions for planting next year.  Well, I might eat ONE of them to see how they rate in the flavor department, but 55 anyway.  That increase is an average of 7 per bulb planted.  This will vary, because larger bulbs produce more smaller onions and vice versa, but — is probably a good average.  In that case 55 should yield around 385 bulbs the second year and if all bulbs were to be planted from there out the numbers would look like:  year 3= 2695 bulbs, year 4= 18,865 bulbs, year5= 132,055 bulbs, year 6= 924,385 bulbs and year 7= 6,470,695 bulbs!  Ok just one more and I think you get the idea- year 8= 45,294,865 HOLY ONION RINGS!  that’s a pretty good increase and not so long to a field full of onions!

The onions ripened early and were harvested ahead of my other potato onions.  That in spite of being planted later than some of the Yellows. Kelly says that the Green Mountain Multiplier comes in ahead of all his others, so they do appear to be early.

Curious Buckeye Chicken on far left, Green Mountain Multiplier in the middle and the largest Yellow Potato Onions I ever remember growing on the right. It will be interesting to observe size differences over a few years when tweaking planting size.

So how can you be the first one on your block to possess the promising Green Mountain Multiplier?  I’m growing all of mine out for at least another season before I do anything with them, and probably longer.  I’d like to concentrate on multiplying them as much as possible for now.  I have a feeling they will become more readily available over the next decade or so as numbers increase.  In the meantime, you can contact Kelly, but they will probably be in very short supply.

Kelly’s success with the Green Mountain Multiplier is encouraging and seems to point the way for further development.  More on that point and on my potato onion seed experiments in some future post!

Update June 28th 2013:  This year I planted all of the Green Mountain Multiplier bulbs I had on the Winter Solstice.  They were plenty hardy and grew well.  Surprisingly, they are already dying down and most are ready to lift and cure in the shade somewhere.  That is great news, because it means that I could beat everyone to market with cured bulbing onions!  As far as I know, there is no way to get a regular bulb onions cured down that fast in this climate, though I may be wrong, no one does it to my knowledge.  The onions did flower a little, but so did some of my yellows planted at the same time though, oddly, not in the same bed.  I will probably continue to propagate most of the bulbs, though I may run out of room unless I expand somehow.

Update, September 7th 2013:  Just sorted through the Green Mountains.  I didn’t cure them very carefully this year, but just stuffed them in some baskets in the shed without any trimming, leaves and all (not recommended).  I still didn’t lose that many to rot, maybe around 20.  The total bulbs I have now, not counting rotten ones, the few I’ve eaten and one I gave to a neighbor to plant, is 390 bulbs.  That means that if one is separated from other bulbs in the cluster enough to easily break it off for planting, I count it as a bulb.  That’s uncannily close to my estimate above of 385 bulbs in the second year, when starting with 8 bulbs.  I’m not totally sure how many I planted, but it was probably close to 55.  There does appear to be less internal bifurcation (internal dividing of bulbs leaving a papery sheath between) than on the yellow potato onion, but I’ll be making a close count of that later.  The onions flowered quite a bit actually.  A rough count indicates that something less than a third of the harvested bulbs have flower stalks.  Also, the flower stalks appear, in many cases, to be coming through the center of the bulb.  That could be bad news for keeping ability.  I’m thinking that planting time has a big influence on flowering here, so I may wait to plant, at least most of them, until close to spring instead of on the winter solstice as I did this year.  Some of my yellow potato onions planted at the same time also flowered, though oddly not the ones planted right next to the GMMs.  I haven’t done a close taste test yet, but otherwise, the GMM does seem to be superior, or equal, to the yellow potato onion in all other ways.  If it has a propensity to flowering that cannot be controlled though, and/or if the bolted onions don’t keep, that could be a deal killer.  I could try to eat up the bolted onions, but that’s a hassle.  Most of the bolted ones are not marketable either.  I’ll need a couple few more years to assess their tendency  to (or not to) flower.

Update, August 30th 2014:  This year onions planted in the fall or winter (I actually can’t remember when I planted them, but either around the winter solstice, or in the fall.) bolted heavily producing large quantities of flower stalks.  Onions planted in the spring however produced no significant amount of flower stalks.  The Yellow potato onions seem to be similar, but I planted those in both fall and at the solstice and they still only produced a fairly small number of flower stalks (which BTW, failed to self pollinate for the second year in a row).  Kelly Winterton says that the seed grown shallots and onions will take years of vegetative propagation before the flowering trait will eventually be suppressed, but I’m not sure what he’s basing that claim on.  If I can suppress the flowering by simply planting in spring, then that’s works for me, though I’m not sure how that will play out in other climates.  By way of contrast though, I picked up a variety called copper shallot in trade from an onion grower.  It looks quite a lot like a yellow potato onion, but larger with a pink tint to the flesh and copper colored bulbs.  It’s quite nice and a little larger than the yellow potato onion.  I planted that one in the fall and it produced only two weak flower stalks.  Almost total lack of flowering is still a primary goal in my breeding efforts.  It might be nice to be able to induce flowering for breeding purposes, but for the most part, I don’t want to see flower stalks.  It may simply be a catch 22 that we want to breed new varieties with increased vigor from seed, but don’t want the offspring to produce seed.  If spring planting will consistently avoid flowering, maybe that will have to be good enough though, or perhaps Kelly is right and they will eventually cease flowering if propagated vegetatively for long enough.  My own potato onion breeding trials are underway now.  I planted the first lot of seedlings in the ground late and many did not go dormant in the fall.  Those that did go dormant were saved over in storage and spring planted this year and most of those did not flower.  Those left in the ground which grew on through the winter flowered prolifically and were all discarded from the trials.




August 23, 2012 - Posted by | Food and Drink Making, Garden Stuff | , ,


  1. Hey Steven – Awesome stuff!! My potato onions (the ones from Territorial Seeds) also went to seed. I have more than I will ever be able to plant, so I will send some off to you so you can experiment with those also. They may have been cross pollinated by Yellow of Parma onion, Egyptian Walking onions, or even possibly some garlic (yes, garlic, even some garlic formed true flowers this year …. CRAZY!!) So anyways, throw mine into the mix and see what happens.

    Comment by autonomyacres | August 24, 2012 | Reply

    • Thanks. I have run into at least two other people who’s potato onions went to seed this year, one of which lives in england. Maybe they all do it in the same year all over the world like bamboo is supposed to. The ones of mine that went to seed the heaviest were ones that I overwintered having been planted too late in the summer to ripen off. They just divided more and stayed green all winter. Mine were probably crossed to some extent with some large bulbing onions nearby. I don’t think they will cross with garlic though. Garlic is a different species. So the ones from territorial went to seed, but the ones I sent you didn’t? They look the same otherwise right?

      Comment by Stevene | August 24, 2012 | Reply

  2. Steven, thanks for the great write-up. I encourage people to read my stuff and to undertake their own research and experimenting. I will be able to start to share some of my bulbs in about October. Please be patient with me on this, as I am just a normal guy and this takes time that I don’t seem to have enough of in my busy life. In October – ish, I will be putting ordering instructions on my little website.

    Comment by Kelly Winterton | August 24, 2012 | Reply

  3. Wow – those Green Mountain are fab! I grow various varieties over here in England but none are that size. My biggest is Mrs Hutchinson’s and I’m hoping to try and get it to set seed next year.

    Comment by Andrea | September 23, 2012 | Reply

    • Yes, the Green Mountain do look great. I don’t have Mrs Hutchinson’s. I’m not sure if it’s over here or not. It looks nice. The potato onions I got the most seed from this year were planted in mid summer, too late too mature. They never died back in the fall, but grew through the winter and flowered in the spring. I dug some up and one had over 120 bulbs in the cluster! Many very small bulbs and tons of flower stalks. Maybe a little late now, to try that, but next year. Plant maybe in august or late july. I also had some that I did other things too blossom, but I’m not sure if they blossomed because of the stuff I did to them or because they were next to other flowering potato onions.

      Comment by Stevene | September 23, 2012 | Reply

      • I’d already planted a few out in August – ready to hopefully flower next spring – to be overwintered in the greenhouse as it’s so damp here that they might rot off if left outdoors. I really hope that I can get some seed from them…

        Comment by Andrea | October 18, 2012

  4. […] POSTS:  Mr Winterton’s Remarkable Potato Onions, POTATO ONIONS!, The Historic Potato Onion Like this:LikeBe the first to like […]

    Pingback by Where to Buy Potato Onion Starts « Turkeysong | October 6, 2012 | Reply

  5. What kind of virus etc do they get? Right some of mine have a gray mold/powder then black spots. I live in graham Washington and we are having a cooler and wetter spring than we normaly do be about 10 degrees.

    Comment by Ed Tieman | May 22, 2013 | Reply

  6. Kelly Winterton most interest article on potato onions.

    Comment by Ed Tieman | May 22, 2013 | Reply

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