Caroline Vurlumis
Lab Partner: Naomi Bosch
Organic Farming
12/15/13
Investigating the effectiveness of a Hoop House
Intro
When discussing possible final projects Naomi presented the idea of making a hoop
house and I joined forces with her for this two-person job. Together we researched different
hoop house designs and came up with a list of materials we would need for a design of our
own. Using a mix of items bought online and recycled materials from the farm we constructed
a hoop house about 8–10 feet long and about 2 feet in width. Adam, the Pomona Farm
Manager, had planted spinach in a bed just a few days before that had been in a greenhouse for
a few weeks. With these already germinated plants we wanted to see how effective a hoop
house would be on plant growth. Our key focus was to test whether a hoop house would be a
beneficial tool for plant growth at the Pomona farm in the Claremont climate. In our research
we found hoop houses were generally used in very cold climates (Bevevino). Although
Claremont can get cold during the evenings during fall/winter its temperature does not nearly
compare to an east coast winter. Nevertheless we hypothesized that a hoop house would be
beneficial to the spinach’s growth, especially on cold Claremont nights. For our experiment we
put a hoop house over half of the spinach plot and left half of the plot uncovered. We
hypothesized the spinach inside the hoop house would grow larger than the spinach outside.
Additionally we hypothesized the average leaf size of the covered spinach would be bigger but
the average amount of leaves eaten would be the same both inside and outside the hoop house.
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Materials and Methods
Constructing the hoop house:
Materials used:
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6 tent stakes (6 inches)
3 PVC pipes (4 feet)
1 PVC pipe (8–10 feet)
Clear plastic sheeting 10-foot by 25-foot
Scissors
Rocks
For this project Naomi and I bought 6 tent stakes and clear plastic sheeting online from
Amazon. Adam kindly gave us a few PVC pipes to use for the structure of the hoop house.
When the materials arrived Naomi and I took one half of the bed and put down three PVC
pipes about 2–3 feet away from each other. Sticking one tent stake into the bottom of each end
of the pipe, we stuck them into the ground right outside the drip irrigation system. Luckily the
tent stakes in the PVC ended up being such a strong base that no other materials were
needed—the frame was done. From there Naomi and I draped the plastic on top and
rolled/taped the excess onto a long PVC pipe so the plastic sheeting could be used in the future.
The width, however, had to be cut to match the hoop house but luckily we were able to
maintain the length of the plastic without cutting it by using the longest PVC pipe. Figure 1
shows Naomi cutting the plastic sheeting on top of the skeleton of the hoop house. Having one
end of the hoop house being on a PVC pipe made lifting the cover on/off easy. Once the
plastic sheeting was on the skeleton of the hoop house we kept the sheeting stable/secure by
placing rocks on the edges. Figure 2 shows the completed hoop house.
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Figure 1
Figure 2
For the experiment:
Materials used:
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Tape measure (cm)
pen
paper
drip irrigation system
For this experiment we were keeping track of spinach inside the hoop house as well as
outside the hoop house. The spinach had already germinated before we started the experiment
and had been planted in the plot a few days before we started our experiment. After we
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constructed the hoop house we took measurements of the spinach the following week. We
eyeballed the five largest spinach plants from each section and measured the plant’s height,
number of leaves, largest leaf width and height, and number of leaves eaten in cms. We did
this for both covered and non-covered spinach. We conducted these measurements each week
with Naomi recording and me measuring each week for maximum consistency. Under the
Pomona Farm’s drip irrigation system our plants received approximately .49 gallons of water
per hour for two hours every day in four segments of 30 minutes or less.
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Results
uncovered spinach 11/13/13
height
leaf width length
2.5
1
2.8
0.5
2.8
0.7
1.8
1
2.75
1
2.53
0.84
uncovered spinach 11/20/13
height
leaf width
3.75
3.5
3
3.5
3.5
3.45
7
6
5
4
6
5.6
covered spinach 11/20/13
height
leaf width
2
5.5
3
5.5
3
4.75
2
5.75
0
4.25
2
5.15
1.6
1.5
1.25
1.5
2.5
1.67
# bitten
leaf #
2
2.25
2
2.25
1.75
2.05
length
leaf #
3.8
4.4
3.65
3.3
3.8
3.79
9
7
6
7
6
7
covered spinach 12/4/13
height
leaf width
length
5
10
3.25
4
6.75
3
4
10.25
3
5
7.5
3
2
9
4
4
8.7
3.25
5.25
4.5
4.5
4.5
6
4.95
# bitten
# bitten
height (cov) height (uncov) leaf width (cov) leaf width (uncov)
3.1
2.53
1.09
0.84
5.15
3.45
1.67
1.74
6.282
4.84
2.624
1.74
8.7
4.9
3.25
2.2
length (cov) length (uncov) leaf # (cov)
leaf # (uncov)
# bitten (cov)
11/13/2013
2.05
1.82
4.8
5.2
11/20/2013
3
2.3
5.8
5.6
11/27/2013
3.79
2.62
6
6
12/4/2013
4.95
3.3
7.4
7
11/13/2013
11/20/2013
11/27/2013
12/4/2013
5
# bitten (uncov)
2.4
3.2
5
2
2
4
4
5
6
5
4
4.8
2.5
3
2.75
3.25
3.5
3
8
6
6
4
6
6
leaf #
4
3
4
3
2.5
3.3
length
covered spinach 11/27/13
height
leaf width
length
3
6
2.5
2
6.35
3.65
3
6.7
1.9
0
4.76
3.17
2
7.6
1.9
2
6.282
2.624
leaf #
3
2.5
2.4
2.7
2.5
2.62
length
3
2
2
2
2
2.2
1
1.25
1.25
1.2
0.75
1.09
leaf #
2.5
2.5
2.5
2
2
2.3
uncovered spinach 11/27/13
height
leaf width length
5.5
2.2
4.6
1.6
4.9
1.4
4.4
1.9
3.8
1.6
4.64
1.74
uncovered spinach 12/4/13
height
leaf width
6
5.25
6.25
4.5
2.5
4.9
2
1.6
2
1.5
2
1.82
length
2
1
1
1
1
1.2
4
4
4
6
8
5.2
covered spinach 11/13/13
height
leaf width
3.75
3
3
2.75
3
3.1
leaf #
# bitten
6
7
6
4
6
5.8
leaf #
3
2
3
1
3
2.4
# bitten
6
6
7
7
4
6
leaf #
4
4
3
3
2
3.2
# bitten
8
7
7
7
8
7.4
5
4
6
4
6
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Figure 3 displays our measurements over a four week time period. The data in yellow
represent the calculated average in each column. The last block of data without any
highlighted features displays the average each week for uncovered spinach and covered
spinach side by side for an easier comparison.
Discussion and Conclusion
In the first week of measurements after the spinach had been covered for one week, the
spinach height across the plot was pretty similar with uncovered spinach at 2.53 cm height and
the covered spinach at 3.1 cm. The average leaf width of the covered spinach was 1.09 cm
width, 2.05 cm length, and 4.8 leaves total. The average leaf width of the uncovered spinach
was 0.84 cm, 1.84 cm length, and 5.2 leaves average. There was no bitten leaf data recorded in
the first week. Nevertheless, the first week did already start to show a slight increase in
average height of the spinach plants. The following week the height of the covered spinach
grew about two cms while the uncovered spinach grew less than 1 cm on average. The leaf
width and length did not vary that much. The covered leaf length consistently remained higher
than the uncovered spinach. The width, number of leaves, and the number bitten did not vary
enough to be significant. In week 4 the average height of the covered spinach was 8.7 cms and
the average height of the non-covered spinach was 4.9—a significant difference of 3.8 cms.
The average length of the covered leaves during week 4 was 4.95 cms, and 3.3 cms for
uncovered—a difference of 1.65 cms, which is a pretty large difference for a spinach leaf. The
number of leaves and the number of leaves bitten, however, showed very little difference and
remained relatively the same.
These results show that the spinach in the hoop house grew significantly more in height
and leaf length. During the month of November in Claremont there was a large variation in
temperature with the highest recorded temperature at 97°F and the lowest recorded
temperature at 24°F according to weather.com. During hot temperature days we checked
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whether the covered spinach were alright and were not overheating. There were quite a few
cold nights during November where the trapped heat in the hoop house would have been quite
beneficial.
Overall this experiment proved to be very beneficial since it showed that even in
climates like Claremont that do not experience extremely cool temperatures can still benefit
from a hoop house. In as short as four weeks, spinach height and leaf length grew significantly
faster in the hoop house than the ones outside. During this experiment there was fortunately
very little room for error. The only potential erroneous actions that could have occurred would
have been inconsistent measuring. Overall the big difference in height and leaf length between
the uncovered spinach and the covered spinach proved our hypothesis was true. In addition our
hypothesis that leaves eaten and number of leaves present would not differ greatly was also
proven.
In the fifth week during presentations (after we had completed the experiment) we
noticed that moss had begun to develop in the soil of the hoop house. In addition, fungus had
begun to pop up where the plastic sheeting met the soil. If we had had more time it would have
been very interesting to take this experiment further and test the effect of the moss and the
fungus on the spinach. This could be an educational project for other EA students. In the future
hoop houses could be very beneficial to the Farm to have a faster harvest during colder
fall/winter months.
References
Bevivino, Vinnie. "Winter Time Growing in Hoop Houses." Seed and Cycle RSS. N.p., n.d. Web. 15
Dec. 2013.
Weather.com
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