I'm Ron Patterson with Utah State University Extension in Carbon County. We
talked a little bit about harvesting onions and when you tell whether to
be - ready to be harvested, the next step is to cure them before you store them.
Curing is a process of getting the onions from this green - semi green - state
to a dry state where they...they are ready for storage. And it takes a little bit of
time, and you need to have certain conditions for it to do well. The
commercial producers do it on a large scale; now you can cure your onions in
the field - they'll go through and they'll lift them and they'll just kind of leave
them in place, and you can semi cure them in the field, but eventually you need to
get them out of the field. The other thing you need to be aware of is if you
have a rainy season - around here about harvest time for onions is our monsoon
seasons. And so we really here in the castle country area of Utah - the high
desert country - we can't store these or cure these onions in the field; we need
to put them out of the rain so that they don't get wet. What that does is it
just increases the chances of getting fungal diseases, botrytis and whatnot,
down through the neck into the onion. So... so our curing process we need to protect
the onions from the sun a little bit, but more from the rain is the problem. You
can lift them and leave them on the ground for a couple of days, but around
here we get storms that build up really quickly in the afternoons, and if
you're not there ready to pull the onions out you've got wet onions and
then you run the risk of higher disease problems. So of course now we talked
about when harvesting, you want the tops to be...to be falling over one of this...
you're going to have onions with this thick bull neck, and they don't store
very well. That neck doesn't tighten down; you want a good tight dry neck when
you're storing your onions and this stays open.
So these onions, it taste just fine but, they're the ones that you want to eat
immediately, put into your food, freeze them, dehydrate them, whatever it is you
want to do. If you're gonna do that, these are just fine. For
storage, these big bull neck onions are not the best ones for storage, you want a
good tight neck and when this dries down it'll be ready to go. Commercial
producers have controlled atmosphere structures - buildings - that they can
control the airflow, control the temperature, and all that kind of stuff.
Here at home we don't have that kind of luxury, usually, so we do the best with
what we can. The optimum temperature for curing your onions is 75 to 85 degrees;
in the controlled atmosphere they'll have forced air that they will blow
through up close to 100 degrees, and it cures the onions down a lot faster. The
way we do it takes two...three weeks to get them properly cured. So what you need
to do is make sure that your onions have air flow through them; I've got this kind
of set up here in my shed, it's out of the sunlight, it's not as cool - well, it's
probably about the right temperature gets around 85 90 degrees here and so,
it's okay. Humidity is probably a little lower than
we'd like it to be; you want the humidity be around 70% well, we don't have 70%
humidity around here unless it's just barely rained, so that's just something
we kind of have to deal with. But you want to spread your onions out; I've got
open areas below here, I can set these onions, and let them cure down as I get
them set up. Now I have also done these in...under my fruit trees; I put them on
pallets and if as long as it doesn't rain you're fine. So in order to avoid
the rain, I put tarps over the top of them to keep the rain off from my onions
while they're curing. I put them onto shelves that are open, again putting
tarps over the top of them so that we can keep the rain off. The most important
part here in the curing process is to let the onions dry, and get the skin
dried off. What we're looking for the scales - you're going to lose about 5 to
8% of your onion weight in the curing process - we want these outside scales to
dry down, we want the top to totally dry, and then the roots will dry off too. At
that point then you can trim the tops off; in our conditions in the home
situation, we want to leave those tops on until they're totally cured. That will
leave less opportunity for the disease organisms to get through the neck into
the wet part of the onion. What we're looking for...to see that you're
totally dried down, I mean, these look fairly dry on the ends and everything,
but you want the neck here to be totally dried down. One good way to
tell: it's got a nice paper skin around it, we don't want to take that paper skin
off we want a good tight paper skin on there, but when you take it and you kind
of rub...if it's not totally cured it'll slip back and forth. So this one isn't
cured, although it looks pretty dry, it's not cured yet. This one we take that and
rub it...there's no slippage on that neck and so that's how you can tell, in
your onions at home there, whether or not they're totally cured down. When you're
done curing - when you think you're done curing - there's a couple things you want
to check for and one of them is: check for damages. Here's an onion that has
dropped, apparently, and it's got some damage here and although it's cured down
at the neck, that's one that we'll want to use up very quickly because it's not
going to store very well. So you check for diseased or damaged onions and then
when you get to where they're cured down, trim them off. The roots will usually
just kind of break off, or you can trim them off, but you want to trim an inch or
two above the bulb. And that neck should bend over - I always make sure I trim beyond
that natural bend in the neck. And then for storage, you don't store them in a
non-breathable container, the conditions for storage - the best conditions for
storage - are 32 to 36 degrees Fahrenheit, so you want that to be fairly cold. Now
if you have a garage that doesn't freeze in the wintertime, that's an excellent
place to put it; that's where my dad used to store his all the time.
If you've got a cold room in your basement or someplace like that, a root
cellar is probably - well, it's better than a room in the house - when things get too
warm eventually the onions will start to
sprout again. After about 30 to 60 days, if it's warm enough, they'll start
to say, hey it's...conditions are right, and they'll sprout so you want to make
sure that you keep those temperatures down below 36 degrees if you can. Root
cellar, humidity is usually a little bit higher than you like it to be as well,
but it's better than a warm room. So a garage would be ideal as long as it
doesn't freeze; get down to about 31 degrees in there the onions will freeze,
and the tissues will freeze, and you'll start getting...they'll rot a little bit
faster; that tissue will start to seep. But if it's 32 to 36 degrees onions will
do very well in that kind of a storage condition, and your humidity - again we
have pretty dry humidity around here in Utah - so humidity is usually not going to
be an issue for the storage part of it. Anyway, so that's how you do the storage.
Some things now: I talked about the thick bull necks on the onions, also the other
onions that will not store well are those onions that have had - that have
bolted - they've got a seed head that has come up out of them, they do not store well.
That neck does not tighten down, so you get disease organisms go through where
they have bolted. And so certain onions you want to use up quickly; get them out
of the way, and then those that have a good tight neck get them cured down, get
them get them dried out, and then you can store them in proper conditions. Now to
take them from - you want to take them from the warm temperatures down to the
storage condition not fast, you want to do that slowly, over a period of time. So
actually leaving them in an unheated barn, or shed, or in the garage - just leaving
them in that so that they'll cool down over a long period of time - is actually
better than trying to cool them down really quickly for our home storage. The
sweeter onions don't store quite as long as the more pungent onions, a
Copra and some of those will store are actually quite a long time. The
sweeter onions usually not quite so long; the Walla Walla and Spanish yellow do
not store very long at all, if you can get a month out of those you're actually
doing quite well. So we have our onions, we got them curing, and then we'll have
onions that we can harvest or use throughout the the winter in our
culinary purposes, and there's just another way to have fun in your garden.