[Trikidiki]

Just been reding the thread about overwintering red onions and got thinking.

Does anyone know what the process is to heat treat onions sets.? I guess it can't be rocket science and wondered if it was possible on a small scale.

Can any variety be heat treated?

Any knowledge would be gratefully received.

[Fisherman]

A trickidicki question Trickidicki. Heat treating sets kills off the flower embryo to prevent bolting and from what I understand the process takes several months. You may not get a great response from your question unless from somone who has been involved and fully understands the process. I guess it's probably not viable to heat treat sets on a small scale.

Have grown heat treated sets for the last couple of years and the results have been very good with next to no bolting. My onion crops did get bothered with mildew this year but that's nothing to do with the heat treatment process (I don't think so anyway)!

 

[Trikidiki]

I've done a bit of digging and found an abstract from an article which suggests if you store the sets at 30 C for 90 days bolting can be reduced by 95%. The site wanted $35 dollars for the whole article so I didn't bother.

If I get time I might have a go.

[Yorkie]

30C is quite warm and will cost a fair bit in fuel to retain that temperature, 24/7, for a month.  I've no idea how I would manage that at home 

[mumofstig]

Airing cupboard?...........not so many of these about nowadays though

(Combi's save energy, but waste water )

[Salmo]

I wonder when you start the treatment. Suttons heat treated ones are not sent out until April so presumably treatment starts early March just as the sets are wanting to grow.

Airing cupboard sounds like a good idea but OH's vests might be a bit strong.

[Trikidiki]

Its a relatively high temp but its only a small volume our heating.

I was thinking of a biscuit tin with a low wattage bulb and thermostat. Kept in the boiler cupboard wouldn't use a lot of power.

[Salmo]

In the Sutton's catalogue it says it takes 20 weeks.

[fatbelly]

Its a relatively high temp but its only a small volume our heating.

I was thinking of a biscuit tin with a low wattage bulb and thermostat. Kept in the boiler cupboard wouldn't use a lot of power.

It wouldn't be cost effective at the scale people like us would do it.
Suttons, T & M et al will buy in from a producer who will do vast amount of sets, which will make it worth their while.

I bought 50 heat treated Red Onion sets from T & M for £3.99 with free P & P delivered late March early April. 50 will be enough for me throughout the year.

[Trikidiki]

....................I bought 50 heat treated Red Onion sets from T & M for £3.99 with free P & P delivered late March early April. 50 will be enough for me throughout the year.

You can buy onions  in Tesco for 87p/kg, but where's the fun in that.

It would be fun just to experiment.

[ecky]

send them on holiday

[Trikidiki]

Great idea.

3 months in the sun to heat treat my onion sets, I'm sure 'her indoors' would approve of that.

[ecky]

espesialy if you went with them