Topic: Advice needed - home grown onion sets

[Ed^Chigliak]

An idiots guide to growing onion sets from seed would be handy so links please if you know any good ones.

I have a 10x4ft bed each year just for onions and would like to grow more varieties. A bought set of just one variety pretty much fills this space. I havn't had much luck growing onions from early sowing so I was wondering about sowing seed now for use as sets next year.

[Melbourne12]

I’ve not grown onions before, but now we’ve graduated from a garden to an allotment, I’m making plans for an onion bed next year.  I’ve found the following sources helpful (including their links to other sites):

http://www.gardenaction.co.uk/  Good introductory site

http://www.50connect.co.uk/   A website for oldies like me.  It has some good and simple advice on growing all sorts of veg, including onions.  Use the search facility to find the relevant articles.

http://www.rhs.org.uk/advice/profiles0103/onions.asp  The RHS don’t seem to have much to say about onions, but what there is, is sound.

http://growingtaste.com/   An American site, but sensible advice, good links.  The varieties they recommend may not be available here in UK, though.

HTH

[growmore]

I dont think we could grow our own sets..
Its a specialised buisness with refrigeration etc I think...
A good way is set seed in heat in jan or feb and pot plants on into 3 ins pots then set these out in mar april..
Here is a way i grow some onions for table .I set seeds very thick in rows and leave thenm to their own devices (no thinning out etc) as they grow and ripen they seem to push one another out of row similar to shallots .Here is a pic of last years Ailsa Craigs grown this way
If left to dry in situ I find these keep very well into winter too.

[philcooper]

I'm with growmore, sets are onions which are stopped in their tracks at some stage. I think if you try it without the correct timings/temperature treatment etc all that will happen when you plant them is that they run to seed.

Onion sets are not all that expensive to buy

Phil

[Ed^Chigliak]

OK thanks. I was hoping it would be simple to lift them and pop them back in the following year. I can see how heat treatment could be something of a problem and storage conditions may not be ideal outside of commercial production. It is mentioned in a couple of books but only in passing and certainly not enough detail to have any real chance of success.

Plan B

I'll try swap some bulbs with the other allotment holders so I have a mixed set. That would be much simpler. Also I'll try again from seed.

Checking those links now.

[fbgrifter]

This is a quote from a book on square foot gardening:

Q: Can you raise your own onion sets?
A: Yes, very easily if you start the year before you want to plant them.  Sprinkle 20 to 40 seeds in a square [foot] or half that amount in a half square if you don't need that many, along about July or August.  Water and weed but don't thin.  In 2 months rake the tops over and let the small bulbs form.  After the tops are brown and dry, pull the plants, dry them in the sun for a few days, and store the sets for next spring's planting.  This is a very good way to get sets of special varities that are only sold as seeds.

I haven't tried this method so good luck with it!

[Melbourne12]

I found this on an American university website, intended for commercial growers:

Onions for sets are seeded at about 55-75 lb/acre. Distribute seed in a wide band so that plants are approximately 1/2 inch apart. Uniform distribution of seed is important in obtaining good yields and size distribution. ...

Store at 32 F and 65 to 70 % relative humidity. The temperature and humidity requirements for onion sets, used primarily as planting stock for early green onions, as well as pearl and boiler onions, are essentially the same as those for large dry onions. Because of their small size, these onions tend to pack closely, so they should not be placed into deep piles. They are usually held in ventilated storage in shallow, slatted trays rather than in bags or crates.

Set onions are handled in mesh or Kraft paper bags for marketing. Low relative humidity and low temperature are important to keep the sets sound and dormant and free from sprouting and rooting. At humidity much above 70 % and at warmer temperatures (40 to 50 F), more of the sets will sprout, develop roots and decay. Onion sets should be stacked to allow good air circulation. A storage life of 6 to 8 months is possible for good quality sets.

The problem for the amateur sounds like maintaining a low temperature and humidity.  You can't use a fridge, because of the ventilation requirements.  I guess if you've got a traditional cellar, without any damp, that would do nicely, but if not, you're going to spend a whole lot on air conditioning!

[Robert_Brenchley]

you'd have to refrigerate the entire cellar.

[Ed^Chigliak]

With DIY onion sets I wonder what % of the bulbs would make it through storage and what % of those planted would then bolt without heat treatment. I guess the varieties offered as sets are the ones that are most suitable for this method of cultivation.

If Mell and his crazy micro managed square gardens knows his onion sets then maybe it's worth experimenting. If on the other hand he's living in square cuckoo land I don't think I'll bother.

[Melbourne12]

It would be an interesting experiment at least.  Perhaps if you sowed the seeds fairly late (end of August?), by the time they'd reached a suitable size we'd have sufficiently cool weather to make storage a bit easier provided you've got an unheated and well ventilated place for them.  They'd need protection from frost, though.

I read in a book somewhere that sets weren't so attractive these days because you can easily get reliable overwintering varieties, and very early varieties for spring sowing.