Seattle’s P-Patch Community Gardens: Exploring Some Aspects of their
Environmental Sustainability
Hannah Wood, Winter 2016
Agricultural production makes up approximately 1% of
the U.S. gross domestic product, but it contributes to 10%
of the country’s greenhouse gas (GHG) emissions (Kassel,
2014). To further illustrate this disproportionality, consider
the following trend: between the years of 1990 and 2013,
the total amount of U.S. GHG emissions increased by 6%
while the GHG emissions from agriculture increased by
17% (Kassel, 2014). This is due mostly to fertilization of the
soil, the production of methane by livestock, and the
management of livestock manure (Kassel, 2014). The
application of nitrogen fertilizer for corn increased by
213.8 million pounds between the years of 2010 and 2014
(Data and Statistics, 2014). This creates an increased risk of
nitrate runoff into near-by waterways. Not only does
commercially grown agriculture create environmental
problems through fertilizer use and greenhouse gas
emissions, it also contributes to the loss of topsoil and soil
erosion, the loss of wildlife habitat, and polluted
waterways (Environmental Impacts of Farming, 2016).
My purpose for this research is to describe how
community gardening compares with commercial
agriculture in terms of sustainability. These gardens have
the potential to decrease the dependency on commercially
produced agriculture and increase the sustainability of the
city of Seattle. They can enhance economic viability by
providing a more affordable method for community
members to obtain produce. They can enhance the
integrity of the ecosystem by being pesticide-free and by
using non synthetic fertilizers such as compost. Lastly, the
gardens can enhance the health and safety of the
producers and consumers by preventing toxic agriculture
run-off found in commercial agriculture and by reducing
carbon emissions.
The gardens evaluated are all part of Seattle’s P-Patch
Community Gardens Program. This program is run by the
Department of Neighborhoods. There are currently 88 PPatches found throughout the city and 14.9 acres of these
patches are used to grow food.
Fisher’s life cycle assessment study of small scale
urban farm conversion from large scale commercial
agriculture results in a 44.5% decrease of energy
use, 105% less water use, and an 87.5% decrease in
carbon dioxide (Fisher, 2014). This means that
urban community gardens have immense potential
in terms of sustainability. Although the
sustainability potential is present for the city of
Seattle, the gardens are not being fully utilized.
54% of the garden plots surveyed were not being
used despite the fact that many winter greens and
other vegetables could be grown.
Research consisted of three steps. The first step was
to collect data on the P-Patch gardeners’ activities via
an in-person interview. A random number generator
was used to assign a number to each P-Patch. Then a
random number generator was used to select the eight
gardens to survey. Two in person interviews were
conducted. One took place at the Climbing Water
garden and the other at the Lake City garden.
The city could implement more education and
outreach regarding winter gardening in the
Northwest and coordinate a planting and
harvesting event for these winter vegetables. The
education and outreach for winter gardening could
be most successful in the form of a series of
workshops and a monthly seminar. The workshops
would focus on year-round gardening in the Pacific
Northwest climate. A partnership with Seattle Tilth
could be beneficial as a way to expose P-Patch
users to resources outside of City departments and
to bring in experienced northwest gardeners.
While at each garden, a record was kept of what
vegetables were currently being grown and noted
whether or not the garden plot had been recently
tended. Plots with less than 10% of the garden covered
by weeds were considered “tended”, plots with 10-40%
weed coverage were considered “somewhat” tended,
and plots with weeds covering more than 40% of the
area were considered “not tended”. Additionally, if it
was made obvious that the garden plot was retired for
the season, it was labeled as “wintered”.
The next step was to conduct a research synthesis of
studies regarding the environmental impacts of
commercially grown produce and produce grown in
local gardens. This synthesis provided data for fertilizer
inputs, carbon emissions- including transportation, and
water usage for each type of crop production. This data
synthesis allowed the environmental impacts of
commercial agriculture and community gardens to be
compared and contrasted.
“Well tended” - <10% weed coverage:
Another alternative would be to start a Winter
Use Program for the gardens. This would allow
those plots which are not being utilized during the
winter months to be passed on to someone on a
waiting list who will grow vegetables throughout
the winter months. This program could broaden
the user base of the garden, extend the benefits of
growing vegetables to a larger number of citizens,
foster a strong sense of community within Seattle
neighborhoods and allow the positive sustainability
impacts of the urban gardens to carry on yearround. The program would be conducted on a
volunteer basis with P-Patch gardeners opting to
allow community members without access to the
plots to coordinate seed transplanting within the
gardens during the month of September. It would
essentially act as an alternating system with a
proposed timeline shown below:
“Somewhat tended” – 10-40% weed coverage:
Conversions from Commercial to Urban Production
(Fisher, 2014)
Data and Statistics. (2014). Retrieved December 1, 2015, from
http://www.nass.usda.gov/Quick_Stats/Lite/result.php?4893DD79-6128-3E25B139-0368894A03EA.
"Environmental Impacts of Farming." Environmental Impacts of Farming. WWF.
Web. 02 Mar. 2016.
Fisher, Stephen. "A Case Study of Urban Agriculture: A Life Cycle Assessment of
Vegetable Production." UMI Dissertation Publishing (2014): 1-267. ProQuest.
Web. 07 Feb. 2016.
Kassel, K. (2014, May 7). Land and Natural Resources. Retrieved December 1, 2015
from http://www.ers.usda.gov/data-products/ag-and-food-statistics-chartingthe-essentials/land-and-natural-resources.aspx.
“Not tended” - ≥ 40% weed coverage:
“Wintered” – retired for season:
Special thanks to my professor, Stanley Asah,
for his mentorship and encouragement. I
appreciate your guidance throughout this
project. I would also like to thank Tom Strid
who has provided valuable feedback and has
shared his knowledge of gardening and
research experiences.
PRIMARY
GARDENER
PLANTS SEEDS
May
PRIMARY
GARDENER
SLOWLY ENDS
HARVEST
PRIMARY
GARDENER
BEGINS HARVEST
Jun
PRIMARY
GARDENER
UPKEEPS PLOT
Jul
Aug
Sep
WINTER USE
GARDENER
PLANTS SEEDS
Oct
Nov
WINTER USE
GARDENER
BEGINS HARVEST
Dec
WINTER USE
GARDENER
UPKEEPS PLOT
Jan
Feb
Mar
Apr
WINTER
USE/PRIMARY
GARDENERS
PREPARE PLOT
FOR NEXT CYCLE