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?