im just thinking about which type of over wintering onions sets to use. last season i used regular senshu yellow and radar red. this yr im thinking of trying the heat treated varities. my red sets all bolted and were unusable but the yellows were superb.

what success rate do the heat treated have

any experiences would be appreciated

First year for heat treated for me, 130 white onions = 1 bolted, 70 red = 1 bolted, I will definately go this way again

most of my reds, not heat treated have bolted, the ones i used last year that were heat treated were far more reliable so i would recomment heat treated, even though they do tend to be a bit dearer.

I didn't realise you could get heat-treated over-wintering sets? I thought only the spring planted ones were...
Anyhoo, I planted Red Cross over-wintered sets last year (not heat treated) and Electric red sets the previous winter (also untreated), and had very few bolters, maybe one or two out of 50. In the spring of this year I planted Red Emperor heat-treated sets and every single one has bolted So I won't be wasting my money on them next year, I'm going to plant Electric and Red Cross to over-winter, and stick to white onions for spring planting.