Onions can be a tricky crop to grow, or at least to consistently grow a good crop of
onions in this maritime climate.
And given how widely available they are to purchase all year round, some people question
how worthwhile it is to devote space in our gardens to grow them, especially with storage onions.
I can see the logic of that argument, but given onions are such n important part of
our diet, I think it's important to try to grow enough onions so that they're available
throughout the year.
This can be quite easy for some parts of the season, and with crops of green or spring
onions to supplement the larger crops of storage onions, we can generally have onions throughout
a lot of the year.
Most seasons I have been able to produce reasonably good yields of onions for storage, and when
the conditions are good it can be a relatively easy crop to grow, especially when grown from sets.
Last year I had quite a poor yield of onions from most of my gardens, with difficult weather
conditions and a lack of weeding on my part being key factors.
This season I’ve had another problematic crop of onions, for very different reasons,
and I’m still not sure if I could have done anything about it.
This season all of my crops of onions in the outside gardens were really badly affected
by downy mildew, much worse than I had seen it before.
It seems that a combination of weather conditions in late spring enabled the infection to take
hold, and it spread through the crops.
I’ve also had some instances of downy mildew in the past, which is a fungal disease that
can spread long distances by spores when the weather is damp, and it's apparently quite
common here in Ireland.
I’m not sure where the spores came from originally, as the disease could have come
in on the sets I bought, or from infected plants from last year that were not disposed
of properly.
It might have come from a neighbour’s crop of onions, or from perennial types of onions
which could carry the disease from one season to the next.
Or the spores could have blown in from quite a distance away.
Wherever it originated from, this downy mildew ended up badly infecting most of the 10 batches
of onions that I had been growing in the six family scale gardens that I’m experimenting with.
Half of the batches were from overwintering sets, and the other half were grown from sets
planted in the spring.
In total nine of the batches were affected, though some more than others, and all of my
neighbours gardens were also impacted.
The only onions that weren’t badly affected were the overwintering batch of onions that
I grew in the Polytunnel Garden.
I seems that they simply matured and were harvested before the disease spread.
When I first noticed the signs of downy mildew on the onion leaves, I wasn’t sure what
the best thing to do was.
I am not aware of any fungicide that would be appropriate in this context, or any remedy
that could help.
The extreme option would have been to pull out and destroy any of the infected plants
immediately, to try to prevent the disease from spreading further, but I was really hesitant
to do this, and at the time I didn’t think it was going to be such a big issue.
With a few of the batches I cut off any leaves that were affected, leaving the rest of the
plant, which would have potentially slowed down the potentially slowed down the spread
of the disease, as well as reducing the yield.
But it would have been better to do this as soon as the first signs of mildew appeared.
With some of the batches I pulled off the leaves later on when they died back, and with
other batches I left the plants to mature without intervening.
Looking back I am not sure what was the most useful approach, given that the spores seemed
to be so widely spread.
In addition to the impact of the downy mildew, we've had wet weather since the middle of
July, with rain on most days.
This was an issue as ideally the onion plants would have a period of dry weather near the
end of their growth cycle, to help with the process of curing while they were still in
the garden soil.
The overwintering onions weren’t so badly affected as they'd pretty much matured before
the wet period had started.
But this season the spring planted onions matured in consistently rainy conditions.
The plants became very wet and waterlogged, with quite a bit of water getting inside the
base of the leaves of many of the plants.
I suspect the leaves dying back due to the downy mildew, and then being removed made
things worse.
When I finally harvested the bulbs, I decided to try trimming off the top of the plants
and draining away the excess liquid.
I was hoping that this would allow them to dry off faster and would reduce the possibility
of rotting, or at least delay it.
A few weeks after harvesting, most of the bulbs are in better shape than I had feared,
but I suspect that many of them will not store well.
As expected, the yield of onions was lower this seasons than it has been in the past,
with a lot of the onions a lot smaller than I hoped would have been produced.
The downy mildew would have had the biggest impact on the yield, as it killed off a lot
of the leaves of the plants before the bulbs had a chance to fully develop.
And the wet conditions will likely reduce the percentage of onions that will be able
to store overwinter and into next spring.
The average yield from the crop of onions in the outside gardens was higher than it
was last season, but about 40% less than it has been in the previous few seasons.
The yields from both the Intensive and the Extensive gardens had a similar drop this
season, with both the overwintering and the spring planted sets being affected.
There was only a marginal drop in the yields from the No-Dig Garden, but I feel that part
of this was because I had been less successful growing onions in this garden in the past.
It's quite hard to calculate the yield per square meter in the Polyculture Garden, because
so many different types of plants are sharing the same bed.
The overwintering onions did quite well, but I did notice that the average size of the
spring planted bulbs was quite a bit smaller this season.
The average size of the onions from the Simple Garden was definitely down from previous years,
with the yield being less than half of what I was able to grow 2 years ago.
In comparison, the yields from the Polytunnel Garden remain consistently high.
The overwintering plants did better overall, and many of the bulbs seemed to have dried
off well enough to store.
But most of the spring planted onions failed to develop the characteristic round bulb and
closed neck or top of the bulb that is apparently necessary for them to store well.
Because of all of this, I figure it would be best to use up the onions from the spring
batches earlier, and to save the bulbs from the autumn batches for eating later in the
season, which is the opposite of what I would normally do.
Looking at all of this I could simply accept this it’s been a bad season for growing
onions, and hope for a better season next year.
But as the weather patterns seem to becoming even less reliable or predictable, I want
to work to be able to reduce the risk next season.
As part of this I'm planning to try to grow a range of different varieties of onions,
especially some grown from seed rather than from sets.
There are apparently varieties that are more resistant to downy mildew than others, which
I'm interested in trialing.
I'm also planning to sow overwintering Japanese varieties of onions from seed that will mature
significantly earlier next year, as I’m anticipating a poor storage of this years crop.
To further reduce the risks, I’m also going to make sure to clear all of the crops from
this season, to hot compost or burry all the debris and rotting bulbs.
I’m doing this to make sure that none of the plants from this season have a chance
to regrow or produce spores next year, which will prevent the disease from overwintering
to affect the crop next year.
I am also planning to keep a closer eye out for the first signs of downy mildew next year
and to remove all the leaves that are infected as soon as possible.
This will add to the workload at a busy time of year, but hopefully it will reduce the
chance of any infection spreading.
I think I'm also going to plant the plants farther apart in some of the gardens, to allow
more air movement, which apparently can also help.
I already practice crop rotation in all of the gardens, which will reduce the chance
of any of the spores remaining in the soil affecting next years' crop.
But because that the wind can bring in new spores from quite far away, there's a limit
to how much I can do to reduce the risk, as so much seems to depend on the weather.
In the end I still have a lot of onions, with over 200kg of onions harvested from the 6
family scale gardens.
But this is significantly less than the 300kg that I would have expected, if the yields
had been similar to what I've been able to harvested in the past.
So, I’ve now had 2 poor seasons of onion harvests in a row, and the weather has been
a major factor in both.
Last year it was a cold and wet spring followed by drought conditions.
This year it we had an extended period of weather conditions that seemed ideal for the
spread of downy mildew, and then we had a wet summer.
I'm glad that at least the crop in the Polytunnel Garden consistently produces a high yield,
that is available quite a bit earlier in the season.
To me this reinforces the idea that a diversity of growing conditions and varieties will make
it possible to provide a more resilient supply of onions throughout the year.
But this does come at the cost of extra work and using spaces in my gardens that could
be used for other crops.
And sometimes I do wonder if it is worth the effort, when it would be much easier to grow
a limited supply of onions for use when in season.
And then to rely on inexpensive and readily available onions from the shops for the rest
of the year.
But I think it's important to try to figure this out, to find ways to ensure a continual
supply of this staple vegetable that is such a big part of our diets.
Onions can be a problematic crop, but learning how to consistently grow good quality vegetables,
can be one of the most rewarding and interesting parts of growing.
Having an appropriate space to allow the onions to properly dry off is a critical part of
being able to store onions over the winter.
In the past, I’ve used sections and corners of the polytunnel, but this isn’t ideal
as its often too hot and humid, and not enough air flow for them to dry off properly, and
I’d really rather use the space to grow crops.
Last year I built stackable racks with a roof, in order to dry off the onions, and this worked
reasonably well for a dry summer, but it wouldn’t have worked very well with the wind driven
rain that we had this year.
This years’ crop is currently drying off under the newly rebuilt roof of my neighbour’s
composting station, which I’m really thankful for, and I’m beginning to see the real value
of this type of open, but covered space.
And once these onions are properly dried, I will have to find an appropriate place to
store them, so that they will last as long as possible.
And storage of the abundance that we harvest from our gardens is a really interesting issue
that will be the topic of future videos.