Thursday, June 21, 2012


Onions.  They're usually one of my no-hassle crops.  Not this year!  The difference is that I used sets this time, rather than seed - never again!

I sowed 80 sets last Autumn, 40 red and 40 white, and until recently I thought they were doing great.  But in the last few weeks they’ve begun sending up flower stalks.  I treated them as I treat garlic, snapping off the stalks halfway.  I’ve always grown onions from seed before, and the foliage always just flopped over when they were ready to lift.  However, snapping off half the stalk leaves the other half standing tall, which is hollow, and with all the rain recently these have been filling up with water.  Then the onion starts to rot from inside.  And apart from the fact that I'm losing the crop, the smell of slimy rotting onion is not exactly pleasant!

You can see the hollow stems here, some full of horribly gungy stuff.  Ick.
 So, I turned to the encyclopedia of knowledge that is the GIY forums on  The best advice as to why this was happening came from Michael Brenock:

"Onions grown from sets is an unnatural way to grow them in that onions are a biennial, grow in first year and produce seed in second year. By harvesting the sets prematurely in the first year and growing them on in the second year it is possible to make them produce large sized onions in the second year. The sets must however be stored beloe a certain temperature (7-8 deg) before planting, otherwie many or all of them will bolt ie run to seed. This year there are very high numbers bolting because of the warm weather in March followed by cold weather. This applies to autumn or Spring planting. Bolters have hollow stems, will not produce bulbs and will not store. Growing onions from seed went out of fashion but can still be done by raising them under glass/plastic in modular trays 6-8 seeds per cell in Feb/March and plant out after hardening off. This year I estimate I will have more than 50% bolters in my garden across two varieties from a March planting."

Ah.  Now I know!  Tim (another blogger on GIY) also suggested carefully snipping off the flower head just below the bud, which leaves a closed stalk.  I was out at the plot yesterday, and given the forecast I decided to lift the dodgy onions.  Only three or four were really rotten and were immediately consigned to the compost bin.  I laid the rest out to dry in the poly and we’ll use them in the next few weeks.  I hung some of them upside down, thinking this might help them drain off any water that’s lodged in the hollow stems…worth a try anyway.  A few more had sent up stalks, so as Tim suggested I trimmed them off just below the flower.  I’ll see if it works!

Either way, it’s back to seed for me next year.

Onions upside down, these are the 'wetter' ones, which will hopefully drain off.


  1. Good information on the Onions. Growing from seed is less likely to produce disease. I usually use sets with few problems. This year with the persistent rain I had a similar problem with water in many of the leaves (planted very early spring), plus rust. I removed all the affected leaves about a week ago and so far only 2 onions were bad enough to dispose of.

  2. Yes, I'd imagine they won't last for months and months, but should be fine for the next few weeks.