growing greens at 5015 2nd avenue - librewebtools -...
TRANSCRIPT
GrowingGreensat5015/50112ndAvenue:Sub-IrrigatedPlantersforSustainableUrbanGardening
Page 1
Overview
In the fall of 2013, CMU provided AHI and
the Pittsburgh Food Bank with technical
information, case studies and possible
layouts for a vegetable garden green roof
at 5015 2nd
Avenue in Hazelwood. More
recently, because of uncertainty about the
long-term use of this building as a grocery
store, AHI requested that CMU investigate
raised beds as an alternative approach to
vegetable gardening on this roof. Raised
beds do not require construction of a
green roof system and would allow
greater flexibility if building tenants
change. They are also scalable so that the
size of the garden can be adjusted to the roof load capacity.
CMU’s research on raised bed load requirements and other construction and maintenance
considerations eventually led to a focus on sub-irrigated planters (SIPs) as a scalable solution
well-suited to the project requirements: lightweight containers for vegetable gardening that are
portable, flexible in size and shape, conserving of water and soil nutrients, and reportedly more
productive than in-ground gardening. SIPs use a soil-less potting mix, so concerns about soil
contamination in a post-industrial city and its impact on food are substantially eliminated. SIPs
can be purchased or designed and built by hand, inviting creativity and innovation in their
construction and appearance. If the sphagnum peat moss in the growing medium is replaced
with a more sustainable material (more on this below), SIP gardening seems to be an excellent
choice for sustainability as well. Integrating SIP gardening into the renovation of 5015 2nd
Avenue introduces this relatively new urban agriculture method more broadly to the
Hazelwood community, providing an accessible, affordable approach that community members
can use to help shift Hazelwood from a food desert to a fresh food oasis.
For a basic introduction to SIPs and their benefits in urban gardening, see the 4-minute TED talk
video by Frieda Lim (Slippery Slope Farm) and Bob Hyland at
http://www.slipperyslopefarm.us/tedx-manhattan-2012.html
Figure 1 Sub-Irrigated Planter at Liberty Sunset Garden Center , a
public demonstration garden by Freida Lim and Bob Hyland in
Brooklyn, NY Photo credit: Steve Boling, website http://www.slipperyslopefarm.us/liberty-sunset-garden-center-sub-
irrigated-planter-systems.html
GrowingGreensat5015/50112ndAvenue:Sub-IrrigatedPlantersforSustainableUrbanGardening
Page 2
WhatIsaSub-IrrigatedPlanter(SIP)?
A sub-irrigated planter is a planting container one that has a water and oxygen reservoir at the
base of the container below the plants. Bob Hyland, a Brooklyn resident who founded the
Center for Urban Greenscaping (CUGreen) and blogs at http://www.insideurbangreen.org/
describes the SIP water and oxygen reservoir as a “scuba tank” for plants. The growing medium
above the reservoir is a lightweight soil-less potting mix that can wick water upwards from the
reservoir to the plants. Figure 1 shows one possible construction approach to raised bed SIP
with clear detail for the water/oxygen reservoir; the depth of this SIP can be effectively reduced
by cutting the bottom channels in half (half-pipe rather than whole, see photos and description
at http://www.insideurbangreen.org/2011/07/toronto-rooftop-sip-city-.html ). This diagram
appears in a fact sheet by Johanne Daoust. That fact sheet is available online at
http://www.pinterest.com/johannedaoust/urban-garden-sub-irrigated-self-watering-sips/ and
is also sent with this summary.
Figure 2 Example of Raised Bed SIP Construction
SIPGrowingMediaandWeight
Although sub-irrigation concepts are found in writings of Liberty Hyde Bailey more than 100
years ago,1 SIPs as we now know them appeared on the market in the early 2000s and targeted
1 For more information, see Liberty Hyde Bailey blog at http://libertyhydebaileyblog.blogspot.com/p/who-is-
liberty-hyde-bailey.html
GrowingGreensat5015/50112ndAvenue:Sub-IrrigatedPlantersforSustainableUrbanGardening
Page 3
vegetable gardeners. A company called EarthBox makes and sells SIPs (http://earthbox.com/ ).
An EarthBox is 29” long, 13.5” wide and 11” high. A filled EarthBox holds 3 gallons of water and
2 cubic feet of soil and weighs about 80 pounds. This means that the saturated load is
approximately 40 lbs/ft3. The components of that load are 12 lbs/ft3 of water, roughly 2
lbs/ft3 for the plastic container with built-in reservoir2 and 26 lbs/ft3 for growing mix. Although
SIP container design for 5015 2nd
Avenue may vary, one approach to estimating the saturated
load for a SIP garden at 5015 2nd
Avenue is to assume that the garden load will be some
multiple of a single EarthBox. As an example, the original green roof layout proposed by CMU
students (without information about or consideration of roof load capacity) showed 27 garden
beds occupying 1,620 ft2 of the available 4,524 ft2 roof area. The design included work space
between the beds and filled most of the roof except for an area near the alley and staircase for
HVAC equipment and garden storage. If the roof garden area were reduced to roughly one-
quarter of that space, there would be roughly 150 SIPs (based on the EarthBox specs given
above) with a total SIP weight of 12,000 lbs. The feasible multiple will be determined by the
building structural analysis.
The EarthBox website provides information about
commercially available growing media for SIP gardening.
The Daoust fact sheet and the websites cited here
describe possible components of a soil-less potting mix
more generally. As Daoust points out, the use of
sphagnum peat moss is not considered sustainable
because peat bogs are being over-harvested. A growing
medium that avoids that ingredient would be preferable.
Coir, made from coconut shells, is a potential substitute.3
Biochar, while not a substitute for peat moss, may be
another useful component of the SIP potting mix.4
WhatCanBeGrowninSIPs?
The picture to the left shows a “self-contained portable
micro-garden” growing on the steps of Chicago’s Museum
of Science and Industry. The garden is a series of EarthBoxes, and the picture appears on Inside
2 Estimate for container weight provided by EarthBox customer service at 888-772-4169.
3 http://www.vgrove.com/index.php?p=What_is_Coir
4 See Hyland blog section under Biochar heading at http://www.insideurbangreen.org/sub-irrigation-aka-self-
watering/page/6/ including the link to the International Biochar Initiative at http://www.biochar-
international.org/biochar . Since SIPs do not contain soil, the biochar benefit in SIPs needs to be explored further.
GrowingGreensat5015/50112ndAvenue:Sub-IrrigatedPlantersforSustainableUrbanGardening
Page 4
Urban Green blog at http://www.insideurbangreen.org/smart-home/. Because the SIP growing
media is lightweight, there do not appear to be limitations to the types of vegetables (based on
root depth) that can be grown in SIPs at 5015 2nd
Avenue. Given the considerations of overall
rooftop load capacity, the use of shallow-rooting greens and herbs may be advantageous to
maximize the total garden expanse and yield. According to the Guide to Setting Up Your Own
Rooftop Garden (published by Alternatives and the Rooftop Garden Project in Montreal with
funding from the Public Health Agency of Canada, 2008), 20 cm (approximately 8”) is sufficient
depth for growing tomatoes and lettuces can thrive in 15 cm (6”) of soil/growing medium.
There is ample published information on urban gardening and root depths for vegetables and
herbs. The Food Bank may want to engage community members in choosing the plants for the
rooftop of 5015 2nd
Avenue, using the total SIP volume allowed by rooftop load capacity to
determine the number and types of containers and plants that will be installed. The Guide
cited above discusses the importance of including perennials in the garden for the beneficial
insects they attract.
WateringRequirementsandRoofDrainage
SIP gardening conserves water. EarthBox provides a comparison of tomato gardening in-
ground versus SIPs that shows slightly more than 30% savings.5 Hyland claims that SIPs use 90%
less water than overhead watering (http://brooklynbased.com/blog/2010/08/05/the-best-urban-
gardening-method-youre-not-using/). Because water is stored below the root zone in SIPS,
evaporation is said to be a minimal problem. However SIPs are not “self-watering” although
they are sometimes mistakenly referred to that way. SIPs are watered via the fill tube that
extends from the sub-root reservoir to the top of the container and they must have a drain
tube at the bottom. From a design perspective, this means that water must be provided to the
roof of 5015 2nd
Avenue and SIP drainage must be planned.6 An automatic watering system can
connect multiple SIPs and this approach is probably most effective for 5015 2nd
Avenue. The
Guide to Setting Up Your Own Rooftop Garden cited above offers examples of automatic
watering systems. The Guide also recommends rooftop storage for gardening supplies.
OrganizationandStaffingforaCommunityRooftopGarden
Hazelwood and the Pittsburgh Food Bank already have experience in community gardening.
The 2008 Guide cited above provides useful information about planning a rooftop garden
layout and coordinating garden efforts and workers throughout the year. While it does not
5 The comparison sheet is linked to the Green Roof Growers blogspot at
http://greenroofgrowers.blogspot.com/2008/07/how-to-make-sip.html 6 Currently, the roof slopes toward drains in the middle of the roof but water ponds there, particularly on the north
side of the roof.
GrowingGreensat5015/50112ndAvenue:Sub-IrrigatedPlantersforSustainableUrbanGardening
Page 5
specifically address SIPs, the Guide does discuss container gardening in Chapter 6. It also
diagrams a multi-container watering system and offers examples of successful rooftop garden
installations in several locations. A copy of the Guide will be delivered with this summary.
Cool(er)RoofMembranes
In the green roof recommendations prepared for
AHI and the Food Bank last fall, CMU students
mentioned Cool Roofs, a servePGH initiative that
made resources available to nonprofit organizations
to coat their own roofs, helping them to save on
energy costs and lower their carbon footprint. That
program has ended, but an initial review of roof
membrane literature suggests that the incremental
cost of a higher reflectance roof membrane can be
less than the energy savings such a membrane
offers. Since there will be substantial areas of the
roof that are not occupied by the garden, the energy impact of the roof membrane deserves
consideration. CMU will provide more information about this in its summary of roof insulation.
InsidetheCaféat50112ndAvenue:Year-RoundOptions
In Montreal, a company called Jard’IN has designed and installed wall-based planters that use
pipes for containers and framing that includes grow lights to produce a “crop” of herbs and
greens in less than 20 days. At a recent visit to Patisserie La Ruche at 4500 Avenue du Parc,
CMU saw one of the Jard’IN installations and learned that at La Ruche, the herbs and greens are
used in the foods they serve. It may be possible to combine the concepts of indoor SIPs with
wall-based planters to provide year-round vegetables and visual interest for the café at 5011
2nd
Avenue. Hazelwood community members and/or students could be involved in their
design, perhaps as a design competition. A selection of picture from Jard’IN’s website is
provided below. More information is available at https://fr-fr.facebook.com/jardinside
Figure 3: Community Garden with SIPs. Photo credit:
EarthBox, http://earthbox.com/community-gardens
GrowingGreensat5015/50112ndAvenue:Sub-IrrigatedPlantersforSustainableUrbanGardening
Page 7
AFewAdditionalLinks
ExamplesofSIProoftopgardens
http://www.insideurbangreen.org/rooftop-gardening/
http://archives.rooftopgardens.ca/index.html%3Fq=en%252Fourgardens.html
http://www.gardenstateurbanfarms.com/our-beginning/ (Garden State Urban Farms began as Brick City
Urban Farms in Newark. There are some similarities between the initial food desert conditions in
Newark and in Hazelwood. See a short video about Brick City at http://earthbox.com/community-
gardens )
DesignIdeasforSIPS
http://greenroofgrowers.blogspot.com/2008/07/how-to-make-sip.html (also includes some history of
their development)
http://www.insideurbangreen.org/sub-irrigation-aka-self-watering/ (indoor SIPs)