Friday, June 26, 2015

Et Tu Allium Ampeloprasum?

Leeks, are you joining your onion cousins in the blooming brigade?

Leek Scape
I obviously have a lot more to learn about growing alliums.

There's plenty of this going on in the onion patch...

Decapitated flower stalks. The Candy and Superstar sweet onions just keep pushing them up. I've learned that if I just remove the flower head that even though the stalk keeps growing and fattening...

that they don't entirely interfere with the development of the bulb. Common advice is to just pull the bolting onions and enjoy them right away because the bulbs won't get any bigger. But that's a lot of onions to try to enjoy at one time, and as I said, the bulbs have continued to grow a bit. The best strategy for me seems to be to keep the bolting onions in the garden as long as possible. They seem to be keeping just fine so long as I remove the flower heads as soon as I see them. At first I was cutting the flower stalk as low as possible, but the problem with that is that the stalk is hollow and water collects inside of it leading to rot in the bulb. Now that I've learned that lesson I'm careful to just snip off the top. It will be interesting to see just how long I can wait before I have to harvest the bolters.

I did make an exception when I found that my small planting of cipollini onions were bolting. I pulled all of them. There really wasn't any hope of them turning into nice little flat bulbs. They were all too big, shading the shallots, and a lot of them were behaving more like bunching onions than bulbing onions, so out they came.

Bolting Cipollinis
Now, I'm finding that the onions that I had hoped would be my storage onions are bolting as well. These were one of the varieties that I started from seed way back in November. Seven months devoted to growing them and now they decide to bloom.

Tonda Musona onion starting to flower

Blooming onions. Blooming leeks. What the heck is going on?

I was really quite careful to choose intermediate day length onion varieties that should be suitable for the latitude here. But day length isn't the trigger for blooming in alliums. Alliums are biennials, they do most of their growing in one year and bloom the next. For many biennials day length is the trigger to bloom, but for onions day length triggers bulb formation, which to the plant means that they are storing food to get them through the winter and provide energy to bloom in the spring. Vernalization, which is exposure to a certain number of chill hours, triggers flower production in alliums. Alliums can be fooled into thinking (do onions think?) that they have been through winter if they are exposed to a period of warm weather followed by cold weather. And that is the likely trigger for the blast of blooms in my onions and leeks. We had an exceptionally warm winter this year, days on end from January through April with temperatures in the mid to high 60's into the 70's and even into the 80's (18-27ºC). And then we shivered through the month of May with temperatures that barely made it into the 60's. It turned out to be one of the coolest Mays in years.

So my challenge now if I want to continue to grow onions and leeks is to find varieties that are resistant to bolting. This is the second year that we've experienced an exceptionally warm winter, although last year the spring weather wasn't quite as cold. Is this the new normal? Who knows. But it's really not unusual, it's almost expected, that we will have some warm weather in winter. We also tend to have fairly cool spring weather when the fog starts to roll in. So I think I need to find alliums that are resistant to bolting when subjected to swings in temperature.

One of the sweet onions that I'm growing seems to be resistant - Red Candy Apple is one of the trio of onion seedlings that I purchased from Dixondale. This is my second year with this trio and my experience this year is the same as last year. We had really similar weather conditions and both the Candy and Superstar onions bolted and Red Candy Apple did not and has not. Red Candy Apple is a keeper.

I grew another three varieties of onion from seed for this year, two of which I've already mentioned as bolting. The third variety is a red torpedo type, Rossa Lunga di Firenze, which is starting to form bulbs now, and so far I haven't found a flower stalk, not yet, but that doesn't mean they won't appear. I've got my fingers crossed that it will be resistant. If Rossa Lunga di Firenze doesn't bolt I'll give it space in the garden next year. The problem with RLF is that it doesn't keep well. I need to find a storage onion suitable to my climate.

Here's a few intermediate day length storage onions that I think I will trial next year, click on the links to go to the seed seller:

Australian Brown - heirloom
Giant Zittau - heirloom
Talon - hybrid
Whitewing - hybrid
Expression - hybrid, not a storage onion, but similar to Candy which I like, it keeps a few months
Great Western - hybrid, not sure it's for storage, but it's suited to my latitude
Mt. Whitney - hybrid, another one suited to my latitude

Here's a couple more tidbits of advice to keep your onions from bolting, courtesy of Dixondale:

Be careful not to over-fertilize, too, because overly vigorous growth may result in bolting. So can soil that is too loose; if the plant thinks the ground has been disturbed, it may respond by trying to spread its seed.

That sounds reasonable but I doubt that either was part of my problem.

I would love to hear if anyone has any suggestions for a great onion that will grow at 36º30' latitude with a longest day of 14 hours and 49 minutes. Long day varieties require 14 to 16 hours to initiate bulb formation so some of them will work here. The challenge when considering long day varieties is that there often times isn't any information about just how many hours are required or which latitude is appropriate. I've passed on a number of long day onions because that information isn't provided.

Back to the leeks. I'm growing two varieties - Blue Solaise and Lungo Della Riviera. So far it's just the Lungo Della Riviera which are bolting. The Blue Solaise are compact and fattening up. The LDR's are more tall and thin, the tallest and thinnest are the ones that are bolting. So I'm hoping the Blue Solaise may resist bolting. I had already decided that the Blue Solaise seem to be better suited for my garden because they have been more resistant to rust than the LDR's, so perhaps they will be keepers.

With all this bolting going on in the onions and leeks I've started to more closely inspect my Zebrune shallots. So far, so good.

One more tidbit about growing bulbing onions. I've noticed that a number of my onions are splitting, as in multiplying, two or more plants form from one seed or seedling. Dixondale advises that it may be because of a number of things including genetics, spacing too far apart, temperature fluctuations (especially below 20ºF), planting too deeply, over fertilization, and uneven watering. Phew, I'm not sure what I can blame for that problem.

Enough of my stinky lily problems. How are your onions doing?


  1. Such a great variety. I've never grown leek before.

  2. What onions? I had to eat them all as green onions. This year even the garlic chives failed which has never happened before in their long residence here. There was nothing I could do to revive them. I like their flowers in omelets. Close to the original Shaker recipe

    1. That omelet sounds like it is delicious. My chives are never happy enough to produce more than a few blossoms and this year they hardly anything grew at all. I guess I shouldn't complain too much, at least I have some onions.

  3. I usually get a couple that bolt on me every year. Last year was my best ever though with none bolting. That surprised me too. I had chard and parsley bolting on me that were in the ground only a few months. I've never had another year where they bolted. We had really cold May temperatures. I thought for sure I'd get more bolting not less.

  4. I am seeing many of my "potato" onions and the Camelot shallots that I overwintered bolting as well. I wasn't sure what to do about that and have just been to busy to look it up so I just left them - obviously that was a mistake. I'll be out this weekend clipping off those flower heads near the top as you have suggested. All my onions are under netting right now, so I can't really tell if only a few or all of them are doing this. I have a feeling that it was our super cold winter that likely caused this, although since I have never overwintered those shallots or potato onions, maybe even a normal winter would have done so.

  5. I only wish my onions did as well as garlic does for me. Though it did take several seasons for me to get the garlic figured out. I was resolved that this would be the year of the onion, but I don't think it will be. I don't think sitting in water on several occasions has helped them any. I did plant quite a few though, so if I get lots of small onions it will be better than no onions at all!

  6. I'm at 33.95 N so a fair ways south of you but in California and in the same USDA zone. If anything we will get warmer winters than you. So all this may not apply to you as well but I thought I'd relate my experience. We;re supposedly in a short day onion area and a few years ago i tried a small trial of about 11 varieties of mostly short day varieties but soem intermediate and long days as well for comparison. The best/heaviest onion turned out to be Walla Walla which is supposedly long day. The downside to that is they matured later, I just picked a great one today for burger onions. The short day ones matured much earlier and allowed me to plant a summer crop after they had been cleared.
    I think what I learned is that it isn't quite so clear cut distinction between long/short/intermediate and so maybe a trial would work for you. These were from November sowing, transplanting in Jan and harvest in early June

    Walla walla

    1. Those Walla Wallas are huge! I had read that they should do ok here but only passed on them because they don't keep well. Hmm, I might have to rethink that. 11 varieties are a lot to try, but that may be what it takes to find some that are reliable producers here. So now I'm curious about which varieties you tried and how well they did.

  7. This is one of the reasons why I don't grow onions. When space is very limited, it's not worth using it for something that stands a very good chance of "malfunctioning". I have grown Shallots a couple of times, and they did OK. As far as remember none of them bolted, but then I did pick varieties that are less prone to the problem. It's ironic that we consider bolting alliums to be a failure, whereas the plants themselves would think they had done well and coped with the different weather! Your question "Do onions think?" is interesting, because plants definitely do alter their behaviour to adapt to weather and soil conditions, which is pretty much like thinking.


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