By Spottedray
wales,
United Kingdom 
Red onion sets bolting.
Hello.
"This question comes from a general rather than gardening specific site.
We have a raised vegetable bed Its filled with good compost and well rotted horse manure it's about 4 years old and is in a NW facing garden on the NW coast of NI
We have had great success with carrots, parsnips, sprouts and beans over the years, some success with beets and this year looks like we are going well with cabbage
However we have no luck whatsoever with onions
This year we tried red onion sets and already they have bolted
How do we grow onions?"
People have more gardening knowledge on here. I have to say I find that that red onion sets such as red baron bolt far more than white ones such as sturon and I don't know why.
Thanks.
3 Jul, 2014
Simple answer. Onion sets are known to bolt. Onions from seeds are less likely to bolt.
If you must grow onions from sets, get heat treated ones and start them off early in the greenhouse before planting out.
Bolting is nothing to do with soil preparation.
Just got up 96 toughball onions, sown Early January. None bolted, and first time for a long time, none lost to soil borne disease.
4 Jul, 2014