Medium - Beyond Soil by MAPS_Publications

Beyond Soil: Investigating Growth Media for Living Green Walls

EVALUATING GROWTH MEDIA FOR PLANT GROWTH, NUTRIENT ABSORPTION, AND WATER RETENTION

Soilless growth medium is an alternative growth medium commonly associated with green walls. This project is rooted in the growing interest in living green walls as an architectural element. When it comes to living green walls, growth mediums are crucial to plant development as they are where the plant ﬁnds nutrients. While traditional soil serves as

the standard growth medium for plants, alternative growth mediums that may be better suited for the situation are being explored. This research aims to move beyond the traditional soil-based approach and recognize how the choice of growth media signiﬁcantly inﬂuences the success of living green walls. Controlled experiments will be conducted to evaluate various

soilless growth mediums for plant growth, nutrient absorption, and water retention. Data collection will also extend to understanding how the growth mediums can address various structural requirements. The anticipated outcome of this project aims to understand how alternative growth mediums can impact and enhance the efﬁciency of living green walls.

1- Photo: the spruce 2- Photo: ICL Group 3- Photo: Woodlands Water 4- Photo: Plant Cell Technology

PROJECTS REVIEW

1. Developing design criteria for active green wall bioremediation performance: Growth media selection shapes plant physiology, water and air ﬂow patterns

2. Experimenting growing media through local bio-resources valorisation: A design-oriented approach for living walls

F1. Overview: This project examines various growth mediums and plant species to evaluate their CO2 consumption and potential for CO2 balancing. Through tests, they determined that the choice of growth medium signiﬁcantly inﬂuences bioremediation performance.

F1. Material/Method: This project picked three growth medium options and three plant species to investigate. The plant species underwent

F1. Developing design criteria for active green wall bioremediation performance: Growth media selection shapes plant physiology, water and air ﬂow patterns

F2. Experimenting growing media through local bio-resources valorisation: A design-oriented approach for living walls

germination in peat moss plugs before being transplanted into the designated growth medium for thorough testing. The experiment used testing chambers to control the variables, conducting 60 trials to collect data on CO2 concentrations. At the end of the experiment, all plants were uprooted to assess root length.

F2. Overview: This project aimed to assess multiple alternative growth mediums in the context of creating

a more sustainable vertical greenery system. The focus was researching and testing the various mediums to see their ecological efﬁciency.

F2. Material/Method: This project used six different growth mediums. A diverse selection of plant species suitable for indoor and outdoor environments was chosen to ensure efﬁciency. The experiment used 21 pots as individual modules, with each plant having six pots and three

different growth mediums. This study also included a control module using a standard growth medium. Each module got the same amount of water to ensure consistency. They ranked the plants on physical and chemical characteristics. The physical characteristics are dry bulk density, total porosity, and water-holding capacity. Chemical characteristics such as pH levels were also looked at.

PROJECTS REVIEW

F3. Overview: This project looked into alternative approaches for wastewater management. Exploring the potential ways in which living green walls could be used as a means for water recycling. The study also investigated using recycled material as ﬁlling/ growth media.

F3. Material/Method: Experiments were done using a modular mini garden system featuring three rows with three pots each. Within each

module, recycled filling materials were used – module A included crushed roof tiles and cocoa fiber, while Module B utilized leftover coconut fibers from textiles. Once everything was set up, a constant rate stream tracer test determined the hydraulic retention time. When it comes to watering, each module receives a consistent feed of water with a peristaltic pump, which is similar to the drip irrigation method.

F4. Overview: This study evaluated root growth to see plants’ potential for growth and sustainability in vertical environments.

F4. Material/Method: In this study, ﬁve different plant species were used, and each plant was cultivated in 3 different types of growth medium. Slabs of pure media were precisely cut to ﬁt into vertical boxes specially designed for the experiment. The boxes, crafted from acrylic, allowed

for clear observation of root growth. The boxes were randomly rearranged once a week to minimize and avoid systematic effects from placement on the workbench. Distances between the boxes were measured to prevent competition. A specialized measuring device was used to measure root growth throughout the growth period. On day 52, the plants were harvested and followed by ﬁnal measurements.

3. Green walls with recycled ﬁlling media to treat greywater

4. Experimenting growing media through local bio-resources valorisation: A design-oriented approach for living walls

F3. Green walls with recycled ﬁlling media to treat greywater

F4. Root growth of perennials in vertical growing media for use in green walls

METHODOLOGY

Testing SetupWater Retention

EXPERIMENT

Experiment:

In this experiment, I will plant a minimum of two plants in two growth mediums. The experiment conditions will be repeated to minimize the chances of ‘one-off’ results. This experiment aims to test water retention, plant growth, and nutrient absorption. By conducting these tests, I aim to gather data on the

performance of different alternative growth mediums.

Water Retention Test:

Water retention will be evaluated using two methods. Firstly, I will monitor the dampness of the growth medium over time by touch. Secondly, changes in the weight of the growth medium will be measured at regular

intervals to help determine water retention.

Plant Growth Test:

Visual observations of plant growth will tracked and noted regularly. Photographs will be taken consistently to provide documentation and reference for comparing growth rates.

Nutrient Absorption Test:

Nutrient absorption will be tested by examining root growth. Plants will be planted in clear containers to hopefully allow for periodic analysis. At the end of the growth period, plants will be uprooted to get a better look at the root conditions.

Growth Rate

Root Growth

METHODOLOGY

For this research, the growth mediums being used are peat moss and coco coir, both mixed with vermiculite. These growth mediums will be used with leafy greens such as kale and lettuce. The research aims to compare the effects of coco coir and peat moss on plant development and establish the differences in the growth mediums’ ability to support plant growth.

Reasearch Questions:

Whatisthecomparativeeffectofcococoirandpeat mossonplants?Docococoirandpeatmossdifferin theirabilitytosupportplants?

Peat Moss

Coco Coir

Vermiculite

Lettuce Kale

1- Photo: Tree.com

2- Photo: Fertazin

Photo: The Spruce

Photo: Treehugger

Photo: Gardening Know How

Peat Moss

Coco Coir

Vermiculite

3 in 1 Soil Tester

Leafy Greens

Clear Planters

PROTOTYPETIMELINE

Investigation

Definegoals100%2/9/242/26/24

MaterialList100%2/23/242/26/24

DesignDevelopment1100%2/23/243/4/24

Identifydeliverables100%2/23/243/4/24

ModelTesting

SetupTestingConditions100%3/9/243/11/24

ObservePlantGrowth100%2/6/242/23/24

ObserveWaterRetention100%3/9/243/16/24

ObserveRootGrowth100%2/13/242/23/24

TestPositioning0%2/23/242/29/24

Full-ScaleTesting

EvaluateResults100%2/6/242/26/24

CombineProject50%2/26/243/2/24

FinializeReport100%3/3/243/7/24

InstallExibition100%3/6/243/10/24

FebApr1,2024 12,2024Feb19,2024Feb26,2024Mar4,2024Mar11,2024Mar18,2024Mar25,2024

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This project is divided into three phases: Investigation, Model Testing, and Full-Scale Testing. The investigation phase has been completed and will serve as the backbone for the upcoming experiments. The next phase, Model Testing, started the week of 2/5/24. Plant growth and water retention were observed as we proceeded with the setup of testing conditions. Since

the planting pots are root, growth can be observed on the sides. However, uprooting and careful extraction from the substrate would be necessary for accurate root measurement and monitoring. The initial plan involved assessing the structural capabilities of the growth medium post-testing; due to time constraints, this could not be adequately tested. Upon completion of all testing, the results will be

analyzed to evaluate how to move forward. The plan was to hopefully integrate this project with others to create a functional living green wall. However, there ended up being a limited combination with other projects. Therefore, this project is a standalone project focusing on plant growth in different mediums.

Hopefully, a successful outcome will

allow for the integration of this project with others to create a functional living green wall. If successful, the living wall will be showcased in an exhibit. However, if not combined with another project, this project will be a standalone. Ultimately, the report will be ﬁnalized upon concluding all work, hopefully addressing the initial research questions.

EXPERIMENTPROGRESS

EXPERIMENT- GERMINATION

The germination of various leafy greens that started on February 6th marked the start of this experimental/ comparative study. The plant species chosen are as follows: black seeded Simpson lettuce, butter crunch lettuce, arugula, and kale. Using a paper towel as the “seed starter”,

approximately 20-30 seeds of each species were distributed on separate paper towels, folded, and enclosed within individual bags. These bags were placed atop a heating and cooling vent to initiate germination. A lamp was used to supplement the sun during the nighttime. This light likely

added a source of heat for the plants as well. The seeds were checked each night to ensure the paper towel stayed damp. The growth of the plants was also monitored during these nightly checks. The seeds germinated for seven days, the longest duration on the seed packet. However, this

extended germination resulted in some seeds developing leaves and roots within the paper towel. Therefore, transplanting required extra care to minimize damage to the growing root systems.

Germination Setup

Germinated Seeds-Day 7

EXPERIMENTPROGRESS

EXPERIMENT- PLANTING

Following successful germination, seedlings were transplanted on February 13th into a substrate comprising 3/4 parts coco coir and 1/4 part soil mixture. Before creating this substrate mixture, the coco coir, initially a dry concentrate, was soaked in water for 15-20 minutes

until it became ﬂuffy. Once loose, the coco coir was mixed with nutrientdense potting soil. The substrate was then distributed into 16 planting pots. This means that each plant species has four planting pots. Four seedlings were placed into each pot to boost the chances of successful

plant growth. The plants underwent a successful transplant into the new substrate and have demonstrated growth in development. To help this development, the plants have been placed on a watering schedule of once every two days.

Planting Setup

Seedling Implant

Testing Subject

Testing Setup Black Seeded Simpson LettuceArugulaButter Crunch LettuceKale

EXPERIMENTPROGRESS

EXPERIMENT- PLANT TRANSFER

On February 20th, half of the established plants underwent a substrate transition, being relocated to a new medium consisting of equal parts soil, peat moss, and vermiculite. The transplant process involved careful removal from the original substrate and placement into the

new mixture. To account for potential developmental disparities between plants initially grown in coco coir and peat moss, newly germinated seeds were planted in a substrate blend of 2/8 soil, 3/8 peat moss, and 3/8 vermiculite. This adjustment aims to allow for a more accurate comparison

of growth performance between different substrates. The difference in planting time will be accounted for in the ﬁnal analysis and presentation.

Transfer Process

Transfer Setup

Testing Subjects

Transfer Subjects-OG Coco Coir

Peat Moss Subjects

EXPERIMENT- Final Growth Observations

Final observations revealed that the surviving plants have remained healthy exhibiting vibrant green foliage. it appears that Arugula and Black Seeded Simpson lettuce have demonstrated the most successful growth in both height and density. Visual observation shows acceleration

and plant growth, indicating potential for further growth by the exposition date. The coco coir substrate (ﬁrst 2 rows) displayed the highest plant density, followed by the transfer peat moss (second 2 rows). It should be noted that the Butter Crunch Lettuce in the transfer peat

moss group unfortunately died off however, the other plants seem to have thrived. peat moss (last 2 rows) has encountered growth challenges as seedlings have died off. However, some seedlings exhibited resilience and continued development. To help showcase the potential of the

substrate for the exposition, chia seeds were added to the ﬁnal row, anticipating growth. Finally, the mystery plant growing in the coco coir substrate appears to be ﬂourishing.

Mystery Plant Growth

Testing Setup

Testing Subjects

Transfer Subjects-OG Coco Coir

Coco Coir Subjects

PLANTGROWTH

Week 1

Black Seeded Simpson Lettuce Measurement

Black Seeded Simpson Lettuce MeasurementArugula Measurement

Arugula MeasurementButter Crunch Lettuce Measurement

Butter Crunch Lettuce Measurement

Kale Measurement

COCO COIR SUBSTRATE

PEAT MOSS SUBSTRATE

PLANTGROWTH

Week 2

Black Seeded Simpson Lettuce Measurement

Black Seeded Simpson Lettuce MeasurementArugula Measurement

Arugula MeasurementButter Crunch Lettuce Measurement

Butter Crunch Lettuce Measurement

Kale Measurement

COCO COIR SUBSTRATE

PEAT MOSS SUBSTRATE

Black Seeded Simpson Lettuce Measurement

Black Seeded Simpson Lettuce MeasurementArugula Measurement

Arugula MeasurementButter Crunch Lettuce Measurement

Butter Crunch Lettuce Measurement

Kale Measurement

COCO COIR SUBSTRATE

PEAT MOSS SUBSTRATE

Week1MaxGrowth

KaleBlackSeededSimpsonArugulaButterCrunch

Week1MinGrowth

KaleBlackSeededSimpsonArugulaButterCrunch

ANALYSIS- PLANT GROWTH

Plant growth was recorded using a combination of visual observation and weekly measurements. Due to the limited duration of the experiment, data collection was restricted to a three-week period. The substrates listed on the graph are 1) Coco Coir, 2) Peat Moss Transfer Substrate, and 3) Peat Moss. The Peat Moss group (group 3) has lower measurements

Week2MaxGrowth

KaleBlackSeededSimpsonArugulaButterCrunch

Week2MinGrowth

KaleBlackSeededSimpsonArugulaButterCrunch

due to it being one week behind the others. However, the observed growth pattern suggests that group 3 will most likely have a similar growth trajectory as the other groups.

Unfortunately, the Butter Crunch lettuce in the Peat Moss Transfer Substrate (group 2) died in week 2. However, sprouts of regrowth were found in the Butter Crunch Lettuce

container. It’s unclear what caused this however, some possibilities could include improper implantation or nutrient deﬁciencies.

Analyzing the data shows that the Coco Coir substrate (group 1) has the highest growth rates across the board, with Arugula growing the tallest.

The Peat Moss Transfer Substrate (group 2) Displayed a high density of

Week3MaxGrowth

KaleBlackSeededSimpsonArugulaButterCrunch

Week3MinGrowth

KaleBlackSeededSimpsonArugulaButterCrunch

plants; however exhibited a shorter stature. Peat Moss (group 3) struggled to promote plant growth, as only a few implanted seedlings continued growing. Some potential contributions include over-germination leading to a fragile root system or loose substrate, which hinders water retention.

ANALYSIS- WATER RENTENTION

Using a three-in-one soil tester, the water retention capabilities of Coco Coir and Peat Moss were evaluated. To avoid any potential disruptions to the plant growth experiment, new substrate mixtures were created solely for the purpose of water testing. These mixtures mimicked

the same levels of the medium as those used in the plant growth test. This test used two soil testers, which were placed into both substrates and left there for three consecutive days. To help ensure more consistent data collection, this procedure was replicated twice.

Analyzing the data on the graphs reveals that the Coco Coir substrate demonstrates longer water retention compared to the Peat Moss substrate. However, the observed differences appear to be relatively small and, therefore, most likely had little effect on plant growth and health.

Water Test Setup

Close up of MeterClose up of Connection Point

Root growth was more complex to assess accurately, proving more challenging than initially anticipated. Precise measurements of root systems mean uprooting the plants from the substrate, which could disturb the ongoing plant growth experiment. Fortunately, the clear planting pots

offer a bit of visual insight into the growth of root structures. The Chia plants also serve as a potential indicator of substrate nutrient levels.

A basic Google search indicates that a healthy root system is a crucial indicator of overall plant health. The general rule of thumb is that the

whiter the root, the healthier the plant. The plant is unhealthy if the roots are darker and softer. Therefore, the visual inspection of plants indicates relatively healthy root growth, as inadequate development could cause the demise of some plants. The importance of root structure

and nutrients can be used to explain the deaths observed in some of the seedlings. Due to the lack of data, it is unclear which substrate provides the best environment for root growth.

“Mystery” Plant RootsButter Crunch Lettuce Roots

Root from Transfer ProcessChia Root StructureArugula Root System

During the experiment, some mishaps occurred, leading to the accidental growth of seedlings. The leftover coco coir substrate was inadvertently exposed to loose lettuce seeds and/or chia seeds when stored in plastic bags. Surprisingly, these mystery seedlings sprouted and grew for approximately a week within the bags. For experimental purposes, I decided to extract a handful of the seedlings and continue their growth under more controlled conditions. Any remaining root structures and seedlings were carefully removed from the remaining substrate.

MISHAP:

Roots in BagSeedlings in BagSeedlings in Substrate

“Mystery” Plant“Mystery” Plant Measurement

CONCLUSION

Data was collected using visual observations and measurements with tools such as a soil tester and a ruler. The data collected suggests that the coco coir substrate provided the most favorable growing conditions for the leafy green varieties tested: Kale, Arugula, Butter Crunch Lettuce, and Black Seeded Simpson Lettuce. This growth medium substrate was comprised of 3/4 parts coco coir and 1/4 part soil.

Based on prior research on the

substrate, coco coir offers excellent water retention, aeration, and drainage properties. However, it often requires nutrient supplementation, such as liquid fertilizers or the addition of potting soil. In the context of a green wall system, the growth medium would need to be monitored for proper nutrient levels to ensure optimal plant health and address any deﬁciencies.

While the peat moss substrate also demonstrated the ability to support

plant growth, it is to be noted that the Butter Crunch Lettuce died in this group. This substrate consisted of equal parts soil, peat moss, and vermiculite.

Based on prior research and observations, the peat moss requires more frequent watering in order to maintain proper moisture levels. The overall growth of the plants was also lower than the coco coir substrate. However, plant growth was relatively consistent, with no extreme outliers.

It is important to know that peat moss releases carbon dioxide into the atmosphere when harvested. Making it a less sustainable option compared to the coco coir alternative. Overall, this experiment yielded successful and positive outcomes. As the plants were able to thrive and exhibit continuous growth throughout the experiment period. Differences in the growth mediums could also be seen throughout the experimental period and beyond.

Final Testing Subjects

Clear Nursery Pots

$13.99

https://www.amazon.com/Nursery-Plastic-Planting-Seedling-Planter/dp/B09NVK2TRT/ref=sr_1_9?crid=3ROUCCMZCO9QD&keywords=clear%2Bpots%2Bfor%2Bplants%2Bwith%2Bsaucer&qid=1706165606&spreﬁx=clear%2Bpots%2Bfor%2Bplants%2Bwith%2Bscaucer%2Caps%2C117&sr=8-9&th=1

Growth Medium:

Peat Moss

$5.99

https://www.amazon.com/Miracle-Gro-Sphagnum-currently-Northeastern-Midwestern/dp/B00GTDICB6/ref=sr_1_6?crid=28S2K8IJFEJNF&keywords=Peat%2BMoss&qid=1706169009&spreﬁx=peat%2Bmoss%2Caps%2C132&sr=8-6&th=1

Coco Coir $8.98

https://www.amazon.com/Compressed-Substrate-Nutrition-Gardening-Starting/dp/B0CB1HRL3G/ref=sr_1_6?crid=1GQ56ODW43D42&keywords=coco%2Bcoir&qid=1706168847&spreﬁx=coco%2Bcoir%2Caps%2C143&sr=8-6&th=1

Vermiculite $8.99

https://www.acehardware.com/departments/lawn-and-garden/lawn-care/soil-conditioners/7194988?x429=true&utm_ source=google&utm_medium=organic-shopping&utm_campaign=organic-shopping

Plants:

Leafy green seeds (lettuce, kale, etc) $ 9.99

https://www.amazon.com/Sereniseed-Certiﬁed-Organic-Lettuce-Collection/dp/B0B5VRDSJR?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A2XWY9XR36K4LP

Soil PH Tester $9.89

https://www.homedepot.com/p/VIVOSUN-Plant-Moisture-Meter-Light-and-PH-Tester-3-in-1-Soil-Tester305131J/328414516?source=shoppingads&locale=en-US&srsltid=AfmBOop7wkzYjkQSqMy5AaVk9JrU4lCWvck82bV3n97yjhQpWXZ5AMnr2Bk

NOTE: ITEMS DO NOT NEED TO BE FROM THE EXACT LINK/STORE LISTED