I do not have a lot of experience growing bush beans, but I always grow climbing varieties of
the same species in the polytunnel each year, as they can be a very productive crop, and are quite
easy to grow as there is already a structure in place to hang something for them to climb.
And although I will probably continue to grow the climbing varieties in the polytunnel,
I have been thinking that the bush varieties of this type of vegetable may be more suitable
for other contexts, and they may be more successful when grown outside this windy
maritime climate that we have here in Ireland. I was originally thinking of just growing a few
small batches to start with, but when I was trying to figure out what to grow in one of the side beds
of the larger polytunnel, I decided to take the opportunity of doing a broader variety trial.
So I grew 15 different varieties of bush beans in the polytunnel this summer,
which is probably excessive, especially with all the harvesting that was needed,
and it was really interesting to see the similarities and differences between
all the different varieties, but selecting which ones to grow again is not so simple.
There are many different varieties of bush beans out there, and I was able
to get seeds from 15 different varieties from 2 different suppliers for this trial.
Most of the varieties that I got to try were described as the classic thin green bean,
usually eaten as the immature pods before the seeds started to develop, and it is
this type that seem to be most popular to eat. But in the mix there was also one yellow variety,
and two purple varieties, and two varieties with larger flat pods that are traditionally grown for
the seeds when they are either half ripe or dried, which can also be eaten at the immature pod stage.
Some of the varieties were also described as being quite early, and others producing over a
longer season, and a few described as being easier to harvest because of the way the plants grew.
Just reading the variety descriptions , I would find it hard to select a variety to grow,
which is one of the main reasons for do a variety trial like this, and I am also interested in the
diversity of how crops like this grow and produce, and how different they can taste,
so that I could gain a better understanding of the range of possibilities, even if I
end up only growing one or two in future seasons. And I have learned from other explorations that
different results can come from different seasons and slightly different contexts,
so I wanted to save seeds from all of the varieties so that I could grow them again.
Although finding the variety that produced the best fresh pods was the main part of
the exploration, leaving some of the pods on the plant to mature and dry added a complication to
the whole variety trial.
I sowed the seeds directly into the soil of the polytunnel bed on the 20th of May,
burying several seeds at each station in case there was poor germination, and I wanted to ensure
that I ended up with 12 plants of each variety after thinning the seedlings a few weeks later.
I wanted the plants to be about 15 cm or 6 inches apart in two rows 40 cm or 16 inches apart, giving
each plant more space than is usually recommended, partially because I expected them to grow more
vigorously in the warm and calm conditions of the polytunnel, and I also figured it was
better to give them more space during a trial like this, but I think that might have been a mistake.
As the plants grew bigger a lot of them were not able to remain upright,
and ended up falling over onto the soil surface, which made it a lot harder to harvest,
and with less air movement around the plants, this seemed to increase the amount of leaves,
stems and pods that rotted later in the season. I also caused more damage to the plants when
lifting them and moving them around while harvesting, and a few plants broke off entirely.
I suspect that if the plants were closer together they would be more likely to support each other,
helping the whole batch remain upright, but perhaps this would not be so effective.
And it also seemed to depend on the variety, as some of them were naturally more sprawling,
growing out over the surface of the soil and over adjacent plants.
Others had a much more erect growth habit, naturally growing much more vertically,
which would have been much better for harvesting if the plants had
been able to hold up that much weight. A few of the varieties had leaves that
grew downwards, almost acting as support or braces for the plants, and the stems producing the pods
growing upwards, which meant that a lot of the developing pods grew above the leaves,
making them a lot easier to harvest. These different growth habits is
definitely one of the factors that I would use to select varieties for growing again.
I didn't harvest as often as I wanted to, partially because of the time it took to
find all the beans, so I didn't pick all of the pods when they were at their prime, which isn't
great when conducting a variety trial like this. But it offered good opportunities to see which
varieties produced beans that developed past the edible pod stage very quickly, and which ones
seem to have been bred to maintain that crisp pod stage for longer, which is definitely a desirable
characteristic for growers like me who don't always get get around to harvesting so regularly.
I also stopped harvesting the fresh pods in the middle of August, thinking I would leave
the remaining pods to develop as dry seeds, which ended up being a good strategy for some varieties,
and I was surprised how many more pods other varieties continued to produce,
which unfortunately I didn’t get to pick.
This presented a problem with trying to get fairly accurate data about the total weight
of the beans harvested, so I decided to count the number of mature or dried pods that were harvested
from each of the varieties and multiply that by the approximate weight of the pods when fresh,
and I added this to the the records of what was harvested in July and August.
This is a bit of a fudge of the data, which is not great, but I think it provides better figures
to be able to make basic comparisons with. And looking at the adjusted overall harvest,
it is interesting that a few varieties produced quite low yields, most of them
were within a reasonably similar range, and two at the ends produced more than the rest.
I need to be cautious about the data for these two varieties as they had empty beds to one side,
which would mean less competition and probably higher yields that distorted the data,
but I have no idea by how much. So excluding the two poor yielding
varieties, and expecting a bit less in comparison from the two end varieties,
the most productive varieties produced about 1/3 more than the less productive varieties,
which is a significant factor to consider, but not necessarily enough to make clear
choices between the varieties, especially when growing in a non-commercial context.
I am usually quite interested in growing varieties that are able to produce something to harvest
faster than the other varieties, especially with the warm season crops.
There is a definite benefit of getting crops earlier in the season, and I have found that it
is generally the earlier varieties that produce more in the cool maritime climate that we have.
Even with in the protected microclimate of the polytunnel, a fast maturing variety can
be useful when trying to grow multiple crops one after another within the growing season.
A few of the varieties that I grew definitely started to produce pods earlier,
with one starting to produce pods ready for harvesting about 55 days after sowing.
By the first full harvest that I did about 63 days after sowing, most of the varieties were
starting to produce pods, though some had a lot more available to harvest than others.
By the second harvest at the end of July, between 68 and 72 days after sowing,
there were definite differences in the yields.
By the 3 harvest about 82 days after sowing some of the later producing varieties were
starting to catch up, though I didn't put in enough time to do a full harvest of
seven of these varieties, and it definitely showed in the lower yields for that period.
But it was the estimation of the potential weight of the pods that I left on the plants
for producing seeds that gave a more complete picture in my opinion, making up for some of the
varieties I failed to harvest fully earlier in the season, and showing the potential for some of the
later season varieties, and that some varieties produced well over a longer period of time.
Selecting varieties from all of this is not so easy,
especially as I didn't do a proper taste test. I tasted each of the varieties when raw of course,
and we ate many of them cooked, but I didn't take to time to do a taste test that involved
cooking samples of each of the varieties so that we could try them side by side one after another
and compare them, and this is something that would be really good to do if I did another trial.
But it is still possible to evaluate the list of varieties on the basis of yield,
how quickly they produced, or for how long of the season, as well as on their growth habit,
how easily they were to pick and which ones seemed to stay as crisp pods for longer.
The Caruso variety just didn't produce well at all, and one of the purple varieties called
Purple Teepee also had poor harvests, and even though it was one of the few varieties that grew
pods above the leaves which were a lot easier to harvest I probably wouldn't grow it again.
The Purple Queen variety and the yellow Helios variety could both be great crops to grow,
especially as the pods are much easier to find against the green background,
and they can make a nice change from the typical green.
The purple variety would be a good one to grow again, but I found the yellow pods grew very
quickly past the tender pod stage which I am looking for, and would have needed much more
frequent harvests, or it could be useful to grow this variety for semi-ripe seeds rather than pods.
Two of the varieties Borlotto and Sanguigno were bred for this semi-ripe seed stage,
and the Borlotto variety did substantially better, and I think would be a good variety to grow for
this type of crop, as well as harvesting flavourful wide and flat immature pods.
Two varieties Speedie and Sprite produced the most for the earliest harvest,
which would be useful to grow as a fast maturing crop for planting later in the season,
or for enabling the plants to be removed early to make space for another crop.
Although there seemed to be very little difference between them, I think I would select Speedie
which seemed to stop growing earlier in the season, as I think this is one of the varieties
where it would make sense to pull up the plants once when many of the pods are ready to harvest,
to make it easier to harvest the beans all at once, saving time and effort.
If I was looking for ease of harvest over a slightly longer growing season,
I would probably select the the Maxi variety that was producing a lot of the pods above the leaves,
even though it wasn't the highest yielding, but I would want to harvest the pods very
frequently before the they toughened. The Marona variety was the earliest to
produce pods by a few days, and produced them over a longer part of the growing season,
and ended up with quite a high yield of pods that seemed to stay at the immature stage longer.
The Stanley variety was slower to get started, but in this trial produced
the largest yield of good quality pods, over the longest period of time, still producing
a lot of pods well after many of the other varieties had slowed down and stopped, and
I think this variety might be the one to select for continual harvesting over a long season.
So in summary, four of the varieties I would grow in slightly different contexts and different times
of the growing season, with another variety being a useful replacement as a fast growing variety.
Three of them I would grow for diversity of colour or for semi-ripe seeds, and another
three varieties I rejected because they were so low yielding compared to similar varieties.
That leaves 4 varieties that are all reasonable yields and qualities,
but not remarkable enough in this trial to want to select for growing again in the polytunnel.
But they might do better in another trial, or be significantly better tasting than the
other varieties, or they might grow well outside or in different contexts, but
the same could be said of all of the varieties. In total I was able to harvest 25kg of beans from
all 15 varieties, at the fresh stage when the pods were young enough to be able to be snapped,
and it seems that I could have harvested about another 12-15kg of beans if I hadn't
left so many pods to mature as seeds. This translates to an average yield of
about 3.25kg/m2, but even with the yield of just over 4kg/m2 from the most productive varieties,
this is still about half the yield I have been able to get from the climbing beans.
So I am not sure bush beans are the best option when I have the possibility of
growing the climbing plants, but they are useful when there is limited space such as
under the slope of the polytunnel plastic or when overshadowing would be an issue.
I also think these plants might do reasonably well in the outside gardens, especially if I
can cover them with temporary covers to protect them from the late frosts and cold nights that we
often get in late spring and early summer. And I would be interested in exploring
the possibilities of growing bush beans for saving dried seed for eating in this climate,
but I might need to find ways to keep the rain we tend to get later in the season off
of the drying pods so that they don't rot. But I am glad I did this variety trial in
the polytunnel this year, because I learned a lot, and I was also able to save a lot of seeds
from each of the varieties to be able to grow in future seasons, and from many of the varieties,
I might have enough seeds to be able to share with lots of friends and neighbours.