I have been growing onions for years but it has only been recently that I have been getting
significantly better yields of better quality onions for storage. Although I have grown some
onions from seed, for quite a few years I have been buying in and planting onion sets for most
of the onions I grow in the family scale gardens that I manage. And with most of these crops I have
essentially been doing the same few simple things, buying onion sets, sticking them in the ground,
waiting for them to grow, and then harvesting. But there are of course other useful tasks that make a
difference and also subtle differences between the gardens that have produced variable results. And
I have made a few upgrades this year, including changing the variety that I grow, and changes
to some of the methods that I use to look after the crops during the growing season, and after
harvesting, that have together helped produce the best crop of onions that I’ve ever grown.
There was quite a range of yield in main crop storage onions that we produced in
5 of the family scale gardens that form a significant part of this RED Gardens Project.
Comparing the total kilograms of onion bulbs that were harvested from each garden, divided by the
total area of bed dedicated for this crop, the Extensive, No-dig and Simple Gardens all produced
roughly comparable yields. The Polyculture Garden produced a slightly lower yield,
but the Intensive Garden produced a lot more, and the onions were mostly very good quality.
12 kilograms of dried and trimmed onions per square meter is the heaviest crop that I have ever
had from storage onions, and sets a new very high bar for all future crops will have to be compared
to. The average onion weight from this garden was also large, which is surprising given the density
of the plants, as it is unusual to get such big onions when they are planted so close together.
Looking at the yields from the last three years, the productivity of this garden has
increased dramatically, and the yield from all the other gardens have also increased quite a bit.
And when I look at the average yield, combining the onion harvest from all 5 gardens,
last year was quite good, and this season was even better with over twice the harvest
of onions compared to a very poor crop 2 years ago. An average of 8 kg of onions
out of each square meter of growing space is quite a bit of food to be able to produce,
especially for a crop that is harvested in the middle of the summer. There are a few things
that I think really helped to contribute to this better yield, and some things that I
think could definitely be improved in a few of the gardens, that could help them produce even more.
Every spring I buy onion sets for this main crop from my usual supplier,
and it was a new variety last year and another different variety this year . I usually try to
stick with the same variety each year, mainly to make it easier to compare one year to the next,
but in this case I'm glad of the change, as the new onion varieties seemed to have
drastically reduced the impact of onion downy mildew on the plants, especially this year.
The variety I used to grow seemed to be much more susceptible to this problematic infection,
which was an issue for several years and significantly reduced the yields a few years ago.
Although there are things that I can do as a grower to reduce the risks and impact of
downy mildew in the gardens, I haven’t been so successful with this. So I'm
really glad that plant breeders have done the work to develop varieties that seem to
take care of this issue for me, or at least within the limited trials that I have done.
Despite the occasional wet weather I couldn’t find any sign of downy mildew on this crop this year,
even with the dense planting in the Intensive Garden which had been decimated a few years ago.
Hopefully I will be able to use this same variety again next year,
or one that is just as resistant to downy mildew, as I think it's made a huge difference.
The biggest issue that I've had with growing onions from sets is that some of the local birds
like to pull the young plants out of the soil. I think they are searching for the worms that can
often be found among the roots of the developing plant. And they can pull up quite a few plants in
a short space of time, which can really damage and set them back, even if I am able to replant
them quickly, so I try to cover all the onion sets to keep the birds away. This year I used
a netting held up off the plants with wire hoops, replacing the crop cover that I used to use. This
allowed the plants to grow quite big underneath, and even allowing the tips of the leaves to grow
up through the larger holes of the netting. It also made it easier for me to see how the plants
were developing, to spot any weeds that might need to be pulled out, and to water when necessary.
Unfortunately I pulled the mesh off of the larger crop in the Simple Garden a bit too early.
I thought the plants were big enough, but the birds did quite a bit of damage
pulling up more than 10% of the plants and damaging the leaves of another 10%
in the process. Even though some of them survived this would have reduced the harvest from this
large planting, so from now on I will try to keep the netting on for even longer each season.
The other main issue I have had with onion crops in the past has been weeds.
It seems that onion plants struggle if they have to compete with weeds,
reducing their access to potentially scarce nutrients and water. And if there are too
many weeds in among the onions this can reduce the flow of air, and apparently increasing the risk of
diseases like downy mildew. I have been getting better at keeping on top of the weeds over the
years, but this season we have been more successful with a zero tolerance approach.
This involved trying to weed all the gardens every week, removing any weeds when they were small,
and we even put in underground barriers to prevent weeds from coming in from the adjacent paths.
And this has been largely successful in all the gardens we managed this year,
and I think the lack of any competition from weeds has definitely helped the onion crop this year.
While competition from weeds wasn’t so much of an issue, competition from adjacent vegetable plants
including other onion plants being planted too close, was an big issue in the Polyculture Garden.
This season I have been trying a different cluster method to manage this integrated
gardening approach, with clusters on onions interspersed with a diversity of other crops.
I had also planted 8 sets in each in each cluster to bring the density of onion plants to a bit
more than what I had done in the Intensive Garden, but I think that this was a mistake.
There was also some really strong broccoli, cauliflower and chard plants sharing the bed,
and there seemed to be just too much competition for the onions.
The overall yield was only slightly less than in some of the other gardens, but this was made up of
a lot more onions that were on average half the size of what was produced in the other gardens.
And quite a few of the onion plants in the Polyculture Garden bolted,
prematurely producing a flower stalk, and giving up on continuing to grow the onion bulb,
which for the plant is a store of energy and nutrients, and is what we want to eat.
This bolting can be a reasonably common occurrence, especially with some types of onions,
but it didn’t occur in any of the other gardens with this variety this season.
For me this is a definite sign of stress, that the plants in the Polyculture Garden didn’t
have access to enough nutrients or water at some point in their growth, most likely
because they could not compete with the roots of more aggressive plants that surrounded them.
This is always a risk with mixed plantings, and I will need to consider changing the range
of vegetables planted in in each bed. Planting fewer onion sets in each cluster would at least
reduce the competition between the onion plants, and I suspect that better fertility in the soil
and closer attention to maintaining good soil moisture levels with additional watering will
help. But the key issue is likely sharing the soil with the roots of too many other
plants that are much better at competing for anything in the soil that might be a bit scarce.
In order to get such large bulbs from the closely spaced plants in the Intensive Garden,
the fertility and soil moisture must have been really good, which is a sign of the success of the
method, or at least we are doing something right. And there are obvious reasons why the same onion
crop in the Polyculture Garden struggled so much, and there are things that can be change to improve
the crop for next year. In the Extensive Garden, the lower yield of larger onions makes sense
because the plants were planted so much farther apart, which is a key focus of this method,
but no doubt things could have been improved. And there was a good yield from the Simple Garden,
despite the bird damage early on, but I still would have expected larger onions from the
remaining plants, and perhaps the soil fertility in this garden can be improved some more.
But it is the onion crop from the No-Dig Garden that surprises me the most. There
was a huge amount of compost added over the past few years to this garden, and with the reasonably
high density of planting, I would have expected higher yields and bigger average bulb size from
this No-Dig garden. I expected it to be similar to, if not better than the Intensive Garden.
I found more rotting bulbs in this garden than in any of the others, which is interesting, and
I wonder if it has something to do with the onion bulbs growing in direct contact with the thick
layer of compost on the surface of the undisturbed soil. Perhaps this compost keeps more moisture
close to the skin of the developing bulb, compared to the more freely draining sandy loam soil on the
surface of the other gardens that is more likely to dry out. I also think that the abundant amount
of compost used in this garden didn’t have very balanced fertility in it, and the lower yields
and rotting bulbs may be more related to an imbalance of the fertility, than anything else,
so it might benefit from supplementing the fertility of this compost next year.
I was pleasantly surprised that most of the plants continued to be really healthy right up until they
were ready to be harvested, despite the periods of wet weather that we had. I usually wait until the
necks of most of the plants had softened, and the tops have started to fall over before harvesting,
trying to find a balance between leaving them in the ground to get as `big as possible and
getting them under cover early. The onions that I grow for storage are one of the few
crops that I need to allow to mature or dry after harvesting, before they can be ready to store,
and how I do this has changed quite a bit over the years. I have dried them in polytunnels,
made stacks of wire racks for them to dry in the wind, and last year I filled my A-frame
shed with horizontal strips of wood so that the freshly harvested onions could hang upside down.
This year I used the same basic method of hanging the onions upside down between strips of wood,
only this time they were supported by two horizontal rails screwed to posts driven into
a section of spare ground. And I used the plastic lined lids that were removed from the cold frames
I built earlier this year, to cover the onions once they were harvested and laid out to dry.
I think this is a better solution, as it means I can still use my shed for storage,
and more importantly it allows the sun in to help speed up the drying process,
but it keeps out the rain, and a lot more wind can blow through the leaves hanging upside down.
This setup also makes it very easy to trim the leaves with shears, which helps the drying
process, and once the inside of the neck is dry, they are ready to move into storage over winter,
at least those that haven’t been eaten already. This one rack was able to dry
over 200kg of large onions, faster and better than any other method I have used in the past,
which will hopefully mean that they will store for longer, and once the
onions are strung up for storage, I can dismantle the whole structure.
We rely on this big crop of storage onions to provide us with onions to eat for up to
8 months from August to April the next year when the first of the onions start to become available
in the polytunnels. So it is important to have a large yield or healthy onion bulbs that are dried
off well and stored appropriately, and this year’s crop has been really successful, even with the a
few of the problematic issues in some of the gardens. The weather this year provided a decent
growing season which really helped. But I think that a significant amount success simply came
from an onion variety that is resistant to one of the main diseases this crop can get around here.
Keeping the gardens free of weeds, covering the young plants to prevent bird damage,
and even the method I adapted to hang and cover the onions for drying are all factors that helped,
which can easily be replicated and further adapted by ourselves and others.
But the interrelated issues of soil fertility and water, figuring out appropriate plant densities,
and trying to reduce the potential competition from other plants, are more complex issues.
These issues are much more dependent on the specifics of the context and the method used,
and we really saw this in the different gardens this season. But the crop from the Intensive
Garden this year really stands out, producing a lot of onions from a very small space, and
I wonder if we will ever get a yield higher than 12kg/m2 in the future. But even the average yield
of over 8kg/m2 across all the gardens is really great, a lot more than I really thought possible.
And this is one of the most interesting things about this RED Gardens Project,
that it regularly produces surprisingly successful results in one or more of the gardens,
which significantly shift my understanding of what is possible. And I think it's really important to
try to understand why this happened, so that we can update the methods in the other gardens
to try to achieve similar results, within the limits of the different methods of course.