I have been growing a crop of tomatoes in my older polytunnel for quite a few years, filling one of
the 4 central beds with these long season plants. I usually get a good crop, and each year things
generally getting better, though there are still things that can be improved.
Because they are such an important crop, and take a fair amount of managing to grow well,
I think that the tomato plants are a good example of the incremental change in methods
and management that can occur with a crop. Every year I do something different,
though usually nothing too radical, but hopefully enough of a change be able
to harvest more of the delicious tomatoes over a longer part of the growing season,
and to make the whole process a little bit easier This season the main change that I made was how
these long plants are hung or supported off the ground to allow them to grow as long as possible.
I sowed the tomato seeds near the end of February, as usual, and transplanted the plants into the
polytunnel bed towards the end of April. Because the plants were quite long or tall,
due to insufficient space and light in the propagation area,
I transplanted them on their side into a fertility enriched trench dug down the centre of the bed.
This allowed most of the long stem to the buried without having to dig too deeply.
I don’t think this is the ideal way to manage these plants, and I would like to improve the
propagation space so that the transplants will be in better shape next year, but the buried
section of stem will grow more roots, helping to feed these plants over the long growing season.
The small part of the plant that was left above the soil was easy to cover with a double layer
of horticultural fleece supported by pipe hoops. This covering together with containers of water
to act as a thermal mass provided a lot of protection from the frost, and kept the plants
quite warm even during a few nights of hard frost that we had during the first part of May.
And it kept the plants warmer in general, especially at night,
which created a better microclimate for continued strong growth during the cold spring we had.
Tomato plants are tall vining crops, or more accurately they are long vining crops, that would
naturally scramble over everything, and would generally grow much closer to the soil surface
Within the context of the polytunnel, I have adopted methods used by many other
growers of planting the plants closer together, pruning them off to one main leader or cordon,
and helping them grow up a length of twine tied to a support wire fixed to the polytunnel structure.
In the past I have wound the tip of the plant around the twine as it grew,
which was a relatively simple process, though something that needs to be done regularly,
and I have accidentally snapped off the growing tip on a few plants in the process.
And it was a fair amount of work at the end of the season to pull out the twine before
composting the remains of the tomato plants. This season I invested in some biodegradable
twine, and biodegradable clips that were designed for this type of crop,
and I found them much easier to attach, especially when the top of the plant had grown too much.
I started the season using only the clips to hold the stems of the plants to the twine,
but later I found that a combination of winding up and clipping was the best option.
I gradually removed the lower clips as the plants grew for reuse higher up on the plant,
and after I took the time to remove most of the remaining clips for reuse next year,
the process of clearing up and composting the crop at the end of the season was a lot easier
But if I wanted to save time I could have simply cut everything down and
thrown everything into the compost, including the clips and twine,
and gathered up the tomahooks for the following season.
But the issue with tall crops like these, especially when they are pruned to a single stem,
is they can easily outgrow the height of the space,
especially in a relatively short polytunnel like this, and to grow out of reach to easily manage.
That means they need to be either pruned off when they reach the top of the space,
something that I don’t want to do, or the plants need to be dropped or rehung in some way.
In the past this involved untying the twine,
letting out some more, and retying it further along the support wire,
which meant I needed to remember to leave enough extra twine at the start of the season which often
got in the way, or to tie on another length to extend the twine, and both options were a hassle.
Of course many other growers have dealt with this issue and someone invented a tomahooks which is
an ingeniously simple piece of bent wire hook that the extra twine could be wrapped around.
This could be simply unhooked from the support wire, a loop or more of the twine let out
and quickly rehung on the wire, saving a lot of time and hassle working overhead.
In my larger polytunnel these tomahooks have been really useful with the large
trial of different tomato varieties, where I gradually lowered the plants to give them
more space to grow vertically, and moving the hook further down the
wire so that the lower part of the plant stems lay along the ground.
This is the easiest method, but it does mean that some of the trusses of tomato end up
laying on the surface of the soil, which is not ideal, and it made harvesting more difficult.
In this smaller or lower polytunnel I decided to repeat a method that I had used last year of
tying additional support twines to keep the full length of the plants suspended above the ground.
In the past this took a fair amount of time, with a lot of tying and untying the twine,
but with the help of the the tomahooks and the clips the whole process was quite a bit easier.
When the plants first reached the top of the polytunnel, I attached a second twine with a
clip around the plant’s stem at about waist height and tied the other end of the twine
to the support wire overhead, I then unhooked the tomahooks, let out a length of twine and
rehung it further down the support wire. As the plant kept growing, I repeated
the process of moving the growing tip further down the bed, and when the plant stem crossed
the support twine of the next plant, I attached it to this twine with a clip.
This was quite easy, though perhaps stressing the clips in ways that they were not designed for,
and a few of them failed with the weight of all the tomatoes, causing some of the plants
to drop during the season, but they were easy to retie and reinforce as necessary.
As the plants continued to grow, I continued to clip the stems whenever they passed the
next fixed support twine, positioning the stem on a slight angle above the
stems of plants already fixed to that twine. This continued until there was a layer of 3 or 4
stems clipped to each twine, creating a horizontal wall of plants hanging up off the ground.
At both ends of the bed, I looped plants around to grow down the
other side of bed in the opposite direction, producing a continuous loop of suspended plants.
And because I had removed a lot of leaves from the lower parts of stem,
the space below the suspended plants was fairly clear apart from the numerous hanging trusses
of ripening tomatoes, which was quite beautiful. This was all good for two of the tomato varieties
which were quite vigorous and tall growing, but the middle variety was considerably shorter,
and the plants were not very healthy, so they didn’t work out well with this method,
especially sandwiched in between the other much more vigorous plants.
This mix of plants interrupted the flow and easy use of this overlapping hanging method,
and the larger variety of tomatoes should have be grown using different method,
possibly just pruning of the growing tip when they got to the top of the polytunnel space.
I had grown 24 plants, 8 of each variety,
and harvested just over 100 kilograms of tomatoes in total, from a 8 square meter bed,
which is definitely the largest tomato harvest I have had from this polytunnel.
This gives a yield of almost 13 kilograms per square meter, or over 2.5 pounds
per square foot, which is really good, especially for such a high value crop.
This translates to an average yield of more than 4 kilograms or more than 9 pounds per plant,
but the medium size Dorenia variety was quite a bit more productive, the Gardener’s Delight
cherry type of tomato being in the middle, and the larger Black Krim variety producing less.
Compared to the yields per plant of these same varieties in the other polytunnel,
the Dorenia did better, the Gardener’s Delight did about the same,
and the Black Krim produced less well when calculated per plant.
But considering that the plants in variety trials were given about 20% more space,
the yield per area is actually significantly better in this smaller polytunnel,
especially with the Dorenia variety. Perhaps there is better soil conditions in this
smaller polytunnel, and we probably gave these plants more attention during the growing season.
But I suspect that the way these plants were hung and supported contributed to part of this
increased yield, as it allowed the plants to continue to grow as long as necessary.
And there was lots of space, light and warmth for the trusses of tomatoes to
ripen without coming in contact with the soil, and they were quite a bit easier to harvest.
With the unusually warm weather that we had this autumn, this ability to allow the
plants to grow for as long as possible turned out to be really beneficial.
And with the extra warmth at the start of the season under the protection of the fleece,
these plants were able to produce ripe tomatoes from the beginning
of July through to the middle of November. 130 days or almost 19 weeks of tomato harvests
is a record for me in this context, and shows the real benefit of starting the plants early
and allowing them to continue to grow for as long as possible,
as well as growing varieties that will continue to produce an abundance over a long season.
When I finally removed the plants, I found that the two more vigorous varieties were between
4 and 5m long, in addition to the buried section of stem, which would have made them even longer.
And it was great to see so many roots had developed from the buried stem.
This is more than twice the height of the polytunnel space, which shows the benefit of
this method, or at least it shows the necessity of doing something to manage these vigorous plants.
I wonder how long the stems would have grown if I had left one or more of the side shoots to grow
as additional leaders, and how much more space I would have needed to give each of the plants.
I was quite pleased with how this crop of tomatoes worked out this year,
and the revised method of hanging them, and the use of the tomahooks and clips made the
whole process of managing them a lot easier. Next year I will probably use this same method
of hanging the more vigorous varieties, but to separate out the shorter varieties and
to manage them using a different support method. As usual, I want to improve the feeding and soil
fertility for these plants, as there were some issues this season, and I definitely want to get
plants in better condition before transplanting I think I will grow the plants in a double row,
rather than in a single trench down the centre of the bed, though I’m not sure
if this will make much difference with the strong root systems of these plants.
In my larger polytunnel next year I want to explore a couple of different options for leaving
some of the side shoots, to have two or more stems or leaders on each plant, but in this polytunnel I
want to use this same hanging method to support a single stem for at least another season.
The ease of harvesting is a definite benefit of this method,
and the clear space underneath seems to help, but I could lower plants a bit, and the tomahooks and
clips make the whole process easier and faster. I really like this overlapping woven structure,
and it looks great in the polytunnel with all of the tomatoes hanging down below the plants,
even if it does take a fair amount of work, but growing tomatoes in this context and climate
is always going to take a lot of work, and the harvests of fresh tomatoes is definitely worth it.