Topic: Onion sets

[AlanP]

Quite a few of the Onion sets that I planted out in April are starting to go to seed. The sets that I planted at the back end of last year are OK up to now. Does anyone know what causes sets to bolt?

[Mrs Ava]

I did a google search and the same thing kept cropping up, lack of water may cause the sets to bolt.  They also said snap the flower stem off.  I believe onions are very shallow rooting, so weeding is a problem....have you weeded and perhaps damaged the roots, therefore stressing the plant out and causing it to go to seed?    I remember there is another posting about onions going to seed, and I understand that they are still edible, but they don't store as well.   :-\

[Wicker]

This was on an onion site but not sure if it applies because otherwise wouldn't the whole crop bolt?  think we all have the problem of some bolting each year

Flowering of onions can be caused by several things but usually the most prevalent is temperature fluctuation. An onion is classed as a biennial which means it normally takes 2 years to go from seed to seed. Temperature is the controlling or triggering factor in this process. If an onion plant is exposed to alternating cold and warm temperatures resulting in the onion plant going dormant, resuming growth, going dormant and then resuming growth again, the onion bulbs prematurely flower or bolt. The onion is deceived into believing it has completed two growth cycles or years of growth in its biennial life cycle so it finalizes the cycle by blooming.

sure someone will come up with a more rational explanation.

[philcooper]

Sets are in their second year.

It is the cunning treatment they receive that stops them naturally going to seed; any form of stress, too hot, too dry etc can cause them to think their end is nigh and they do the plant thing - try to produce seed