I’ve had mixed success in growing onions in the past. Some crops have been great, especially from
the polytunnel, but other crops have been really problematic with significant disease issues,
and I ended up with poor harvest that didn’t store very well. I rely on a big batch of spring
planted sets for my main crop of onions, which will ideally store well and provide a regular
supply to the kitchen from mid summer through to end of the spring of the following year.
After a bad crop last year, I was really glad to grow a great crop of onions this season,
with a large yield that was largely disease free. But growing good onions is one thing,
and of course the main part of process, but drying them and allowing them to cure so that they will
store well is another big part that I've struggled with in the past. And then there's the cleaning
and processing of the onions and storing them in reasonable conditions so that there's a good
chance that at least a few of them will still be edible up to 10 months later. I think I did all
three of these things quite well this season, though there is always room for improvement.
Last year my main crop of onions which I plant as sets in the spring were badly hit by mildew,
which was compounded by poor weather conditions as the plants were finishing their growth cycle. I
still had a lot of onions to eat, but they were not so good, and didn’t store as well,
and I didn’t have lots to share. This season I selected a different variety of onion sets
for this main crop, a variety that apparently has been bred to be more resistant to mildew. I
planted these sets in the early spring, in the same series of 5 different gardens,
using broadly the same methods and plant spacing or density that I have used in the previous years
for each of the gardens. I covered the onion beds after planting with a crop cover to protect them
from birds who have had a habit of pulling the sets out of the soil for some reason,
and removed the cover when I thought the young plants were established or big enough. But
shortly after removing the cover from the large batch of onion in the Simple Garden,
a lot of the onion plants we damaged or bent over in one area,
and it seemed as though a couple of large birds had trampled them for some reason.
And there are always a few sets that don’t grow for whatever reason, but beyond these issues,
the onion plants grew well for the remaining of the season, and we were able to prevent
any competition from weeds. As the bulbs of the plants began to swell, with a lot of them becoming
quite big, I started to get worried about the wet weather we were experiencing at the time,
and was concerned that mildew would once again be an issue. But thankfully there was no real sign
of mildew or other disease, and I assume this was because of the resistance within the variety that
I used. But there could have been other factors this season, and unfortunately I didn’t plant
the other variety that I had problems with in the past as a comparison, so I won’t know for sure.
Growing good onions is the first task, and undoubtedly the most important, but after that
I need to be able to dry them properly, which in this Irish climate means finding a place
under cover out of the rain. In the past I have set the harvested plants out on an empty bed
of the polytunnel, or strung them up from the polytunnel structure, but I don’t really want
to occupy such valuable growing space this year, especially with so many onions to harvest. Two
years ago I built a set of stacking racks lined with chicken wire, and this worked reasonable well
as an outside drying space, but the plants were still exposed to the wind driven rain
and a lot of the plants ended up lying on top of each other., so delayed their drying. Last year
I had to trim off the leaves of all the plants as they were harvested, as many of them were soaking
wet and I wanted to speed up the drying process and set them in trays under cover. This year
decided to try to dry the onions in an A-frame shed that I was making out of reused large metal
frames clad in plywood, that was open to the wind on both ends. But this meant that I had to delay
harvesting the onions for longer than I had wanted while I worked to get the structure in place. I
had read somewhere years ago about a method of drying onions that involved hanging them
upside down between pieces of wood, and this structure was a great opportunity to try it out. I
fixed two rails to either side of the A-Frame, and cut a lot of other pieces of wood to span
between the rails to serve as a cross rack. As I harvested the onions from the gardens I hung
the from the racks right away, so that we could minimise the moving and handling of the plants. I
set out each line of onions on the previous row, with their leaves hanging down,
placed a new piece of wood up against the plants with just enough space for the stems,
and then set each onion down so the bulb was resting on the two pieces of wood. In
this way I was able to make sure that each onion was barely touching its neighbours,
and that there was plenty of air circulation between the leaves hanging below.
I attached a piece of crop cover to the end of the shed toward the prevailing wind, in order
to act as a partial rain screen, but to still allow a lot of air movement through the space,
especially between the hanging leaves. This is the best method I have used for drying onions so far,
even if it does use a fair amount of wood, and it was wonderful to see
almost 600 onions harvest from all the gardens laid out in one space.
The onions dried over a number of weeks, and it was nice to not to have to worry about them,
or to need to regularly reposition the onions so that each one of them dried fully. Although
all of these plants dried without being exposed to sunlight, they seemed to dry quite well. I
find that there can be reasonably good drying conditions here in Ireland because of the
typically wind conditions, and the air tends to not be too humid for a lot of the time. We
have been eating some of these onions as they dried, and a few of them were not great, with
signs of rot, but most of them were in really good shape. And as I started to trim the long leaves to
prepare them for storage, I did notice that there was still some moisture in some of the plants,
and I guess the drier outer leaves were helping to keep the moisture inside. I remembered too
late for this season about recommendations to trim the leaves in stages as they dried, which didn’t
make sense to me at the time, but I suspect that this is to help speed up the drying process of the
inner leaves, but to still keep most of the leaves on for long enough so that the onions cure well.
Finding a good way to store the onions is the final step, and the method I have used in the past
is to hang them from string in a cylindrical shape. The first part of the process is to tie a
few onions to the bottom of the string, and attach the top to something secure. Then the remaining
leaves of each additional onion are wrapped around the hanging string and folded under the bulb. I
have found that this keeps the onions in place quite well, and with all of the roots facing
outwards, which keeps them dry and it is easy to inspect all the onions for signs of rot,
at least at the root end of the plant. I hang these cylinders of onions in my house,
either in the pantry or in the kitchen, and we simply pull off each onion as needed. They
seem to store quite well this way, though I generally loose a few as the winter progresses,
and it will be interesting to see how well this year's harvest will store.
Overall this has been a great crop of onions for storage, perhaps the best I have ever grown. The
yield has been good, with an average of more than 6kg of onions produced from each square meter of
growing space, weighed once the onions were dried and trimmed and all the rotten ones discarded. The
batch grown in the Intensive Garden definitely produced a higher yield, and this would be
expected with the higher density of planting, or more plants squeezed into a smaller area.
In general the yield goes down as the densities of planting in the different gardens goes down,
except for in the Polyculture Garden where it is difficult to estimate the density of onions
in the mixed planting of multiple crops. But looking at the average weight of the bulbs from
each garden, I would expect that the size would increase as the density went down,
or as the spacing between the plants got bigger, but that is not always the case. The
average size of the onion bulbs harvested from the Polyculture Garden were smaller,
though still quite respectable and much better than last year. The bulbs from the Intensive
Garden were surprisingly large, almost the same size as from the other gardens, even though there
were many more plants in the same area. The onions from the Simple Garden were definitely
the largest, but perhaps this is partially due to the loss of some plants early in the season
after the bird damage, as this would have meant that the remaining plants would have had more
space. Looking at the number of bulbs harvested compared to what was planted,
the Simple Garden did have a higher percentage of lost bulbs which would back up this idea. But
the Intensive Garden also had a higher percentage of bulbs lost and I suspect that this was due
to more rotting in the bed because of higher humidity with the closer spacing of plants. There
are always a few plants that don’t make it, either because they are damaged when young,
or they rot at some point. And it is interesting that all gardens lost at
least 20% of the plants, assuming that I didn’t miscount somewhere along the way.
Overall I'm quite pleased with onion crops from all gardens, which is a bit rare for me,
as I am often disappointed with the results from at least one of the gardens with the
different crops that I grow. There were some issues, but nothing too problematic, and I am
not really sure how I would improve things in each of the gardens for next season's crop. But
I do want to keep an eye on possible reasons why 20% of the sets that I planted at the beginning
of the spring didn’t end up producing a useable onion at the end of the season. The main thing
that I want to improve next year is to harvest the onions a bit earlier, but now that I have
the shed build and the wooden racks cut, I will be ready for next season. And it would have been
good to get them dried faster, so I definitely want to try progressively trimming the leaves.
I also might try setting up a similar drying rack process in a propagation polytunnel that
I'm planning to build, to take advantage of the warmth of the sun in the drying process. It will
be interesting to see how long this season’s crop of onions will last in storage, but at least they
seem to be off to a good start. And we have plenty of onions for the rest of the autumn, winter and
spring, and lots to share with neighbours. It's great to feel that I've had good success
with growing and managing this important staple crop, and I hope that the harvest next year
will be just as good, if not better, as I plan to repeat the same growing methods in these gardens.
But I also want to develop the space to explore growing a number of different varieties especially
from seed, and it will be very interesting to see how these different varieties compare
with the success that I've had with the variety that I grew this season.