Sunday, January 4, 2015

Onion Culture

Patterson_onion

 

My onion plant order is placed! The only allium I will have to start from seed this year will be the Saffron shallots. I took other bloggers’ advice and ordered my plants directly from Dixondale Farms. Not only is the price cheaper for the two bundles I was planning to order, but it gets cheaper by the bundle, so it’s hard to resist. In addition to Copra and Red Zeppelin, I wound up ordering the Tropea onions I usually grow as well as a mixed bundle of intermediate day onions (Candy, Red Candy, and Super Star). So I will have 200-280 plants showing up mid-April and just have to figure where I will put them.

 

Dixondale has a lot of growing information and I learned a lot just by watching a couple of their videos. I already knew that up North here I plant long-day onions so that after the solstice when days grow shorter, the onions are triggered to start forming bulbs. But there are some tricks to getting the largest bulbs that’s probably obvious to everyone else, but wasn’t to me.

 

Supposedly an ideal onion will have about 13 layers or rings (ideal meaning that’s about as much as you can expect to get in a growing season). Each ring in the bulb corresponds to one leaf of the foliage. When daylight triggers bulb formation, the layers start expanding, so the more layers (i.e., the more leaves), the bigger the onion bulb will be. A healthy, rapidly growing onion can grow a new leaf about every two weeks. The plants from Dixondale will have 4-5 leaves and a healthy root structure (versus the 2 leaves that my own transplants have). To get to 13 leaves, it will take another 16-18 weeks after transplant, given ideal conditions. Onions are heavy feeders and require a lot of nitrogen to encourage foliage growth.

 

So the formula for big onions is:

  • Plant as early as you safely can. The clock is ticking and you want as much foliage as you can grow before bulb formation commences. Once the bulb starts forming there will be no more foliage growth.
  • Buy plants. Ignore the cost, the extra 2-3 leaves they have over homegrown transplants is worth 4-6 weeks of time in your garden.
  • Space onions 4 inches apart in the row, with rows 16 inches apart. Plant onion plants no more than 1 inch deep. The reason for the row spacing is that while onions are shallow rooted, they do develop extensive side roots. In raised beds, they recommend a minimum 4” x 8” spacing. I am going to have to play with the geometry of this for my raised beds. And there is the question of, would I like to have more, smaller onions or fewer but larger?
  • Use a general purpose fertilizer with lots of phosphorus (something like 10-20-10) for good root development when planting. Maybe add bone meal to get the extra P. If you are pushing the limit and planting very early, Dixondale has found that high potassium levels in the soil help protect against freeze damage. In addition to NPK, onions require a lot of micro-nutrients for healthy growth, including magnesium, zinc, boron, copper, iron, manganese and molybdenum, so make sure they are in your fertilizer (or throw in a handful of rock dust).
  • Then starting at two weeks after planting once roots have established, use a nitrogen fertilizer every two weeks. Stop fertilizing when bulb formation starts.
  • When bulb formation starts, make sure the onions have plenty of water. Stop watering when foliage falls over and let the soil dry out before harvesting.
  • Watch for onion pests like thrips and spray if needed.
  • Use a preventative organic  fungicide regularly. Even if fungus disease is not visible, any spores present may increase spoilage and reduce storage time.

 

The nitrogen fertilizer they recommend is ammonium sulfate, which is a chemical fertilizer and not suited for organic gardens. I will most likely use blood meal. If you have a blood meal rated 13-0-0, you apply a cup per 20 foot of row. I will also be amending the beds with the onions with rock dust and kelp meal to get the micronutrients into the soil.

11 comments:

  1. I've been using a 6" grid spacing for a while now and like it quite a bit. It produces a lot of onion in the space. Though sometimes I put some closer and harvest early for green onions. I plan on ordering from Dixondale too this year for the first time. I have no trouble getting big enough starts, but they take a long time under lights to get that big. Nothing else gets started that early.

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    1. 6" is 4 per square, which is what I have used in the past. The onions are always the first things I start but they take up room under the lights. Buying plants means one less thing to juggle this year.

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  2. My planting scheme is dictated by my drip lines. I planted 3 rows with the largest plants 4 inches apart, one row of each variety. Then I planted one mixed row with the plants 2 inches apart using the smaller plants, I'll thin those as spring onions. My drip lines are spaced about 9 inches apart so that's how far apart the rows of onions are spaced. That scheme seemed to work last year. I ended up with over 100 plants in the ground and about 30 tiny extra plants that I have to figure out where I can squeeze them in to grow as scallions or spring onions. The bundles of onions from Dixondale are quite generous but the plants are a mix of sizes, so you will get some tiny plants with just a leaf or two.

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  3. You sure do make it tempting to purchase onion transplants instead of growing from seed. I generally have good success as long as I purchase fresh seeds. Plus I like sowing a few seedlings under lights in the middle of winter.

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    1. Well, I still have to start my shallot seeds so I will have some onion seedlings under the lights, just not as many. Oh, and I'm building a new seed starting rig using a baker's cart and some T-5 lights, similar to what you have.

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  4. I just checked Dixondale and don't think they ship to Canada. I've had varying success from germinating seeds and prefer sets. But it seems you have actually ordered plants (not sets)? I didn't even know that was an option to ship ... either way, I'm trying to find something online. Whether I buy sets or plants locally, they are always generic and I'd love to try Ailsa Craig.

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    1. Unfortunately, onion seedlings are live plants and subject to plant quarantine requirements. So you have to buy in-country, but it's hard to duplicate the climate of south Texas in Canada. Starting seedlings from seed in Feb-Mar is probably your best option.

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  5. As Susie said, our options in Canada are virtually non-existent. Really, the only source we have if we want to get plants (not sets) is at the local garden center, where they are sold in cell packs and often the only indication of variety is a generic yellow or red onion label. If you want to grow a specific variety, you have virtually no choice but to start with seeds.

    As for the onion size, if I had to only choose one size, I would probably prefer medium sized onions instead of large onions. Not to say that I don't appreciate large onions - I'm sure everyone loves the feeling of accomplishment when you hold that whopper in your hand! But many recipes call for one medium onion and always having to save a portion of a large onion in the refrigerator is a bit of a pain; cutting up a couple of medium onions if you need a large onion, however, is not a big deal. Ideally, however, I like having some medium & some large so that I can pick and choose based on the recipe.

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    1. Actually, in response to Susie's post, I tried searching for Canadian seed companies that might sell onion plants. The searches kept coming up with companies selling marijuana seeds LOL. The bag of hemp seeds I put in my smoothies does say it is produce of Canada. Good stuff. I'm with you on the onion sizes, I mostly use medium size onions.

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  6. I have never grown onions (occasionally I have had Shallots), because I don't think they represent good VSR. They are easily available in all the shops and usually very cheap to buy, so I use my precious garden space for other things. Having said that, I bet an onion eaten fresh from the garden is a beautiful thing, and probably much tastier than one which has been stored for ages!

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    1. Mark, you may be right for the common yellow onion, but many of the onions I grow, like the Rossa Lunga di Tropea, and the sweet onions Candy, Red Candy, and Super Star, can't be found at the store nor at local farm stands and farmers markets around here. So I get variety (and quality) I can't easily purchase.

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