J/onions too strong

[tomatoada]

Last year I grew some Japanese onions.  They were planted in August 2008 and harvested in July and August 2009.   They were sweet and mild.  Just as I like them for salads and omelets.   I have started using this years crop as I have grown quite a lot and they are quite big.  They are so strong and almost bitter.   Any ideas why the difference.  Are there different types of J/onions?  I bought them from the same supplier.

[tomatoada]

[chriscross1966]

Different variety?... THere are lots..... also the over-winter temps will have an effect

[goodlife]

Are they same variety?..comes first to my mind, as supplier is not guarantee for what you are buying. Growing conditions have an effect for the flavour too..weather, ground condition, fertilisers..everything really..but saying that..did you eat previous lots before they were fully mature?..and were their flavour developed to sweet and mild in 'un-mature' stage?

[tomatoada]

I used the ones last year from late August onwards.   This time I am using them earlier.  So could it be they will become milder in August?  That would be nice.   Do you know the sort which are mild and sweet so I can choose the right ones for planting this year?  I will use this years for chutney if they do not change.
Thanks for replies.

[goodlife]

It quite possible the flavour to change..many fruits and veg goes trough changes during they development..though usually other way round..normally flavour tends to intensify closer to maturity..but even the amount of water will have an effect for the flavour..we've just had dry spell..so you would think that veg that has not received much water could taste more bitter than one that is lush and full of water.. ::)..just try some again after couple of days of rain..it would be interesting to find out if there is change ;)

[tomatoada]

Will keep testing and let you know.   
Researching for next crop.   

[goodlife]

 ;D ;D..and in mean while look into your cataloques for varieties that are mentioned to be mild..that description should apply no matter what the conditions are.. ;)

[Tee Gee]

I agree with 'Goodlife' re water or lack of!

I think of flavour in the following manner;

Every onion starts of with a given amount of 'acid' in its make up choose what size it will ultimately grow to.

As it bulks up i.e.  the bigger the onion becomes the milder it becomes, to the point that sometimes when peeling an egg sized onion you can sometimes find it makes you cry more than say a 4lb+ onion does.

The bulking up process of onions is mainly water therefore the acid content is more diluted.

As I say this is MHO on flavour and I will keep on  thinking this way until someone comes up with the definitive answer.

Any experts out there want to disprove my theory  ::) ;D