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Chronicles of PRRM Rooftop Gardening

Joshua B. Guinto
PRRM Consultant for Sustainable Village Technologies
July 2009


An urban garden at the PRRM building in Quezon City was a project conceived since 2006. In 2006 a hydroponics projects was installed on the rooftop. Lettuce was grown in a liquid medium. In 2007 another garden was installed in clay jars at the penthouse. However, both projects were not sustained and left the rooftop and penthouse bare.

The combined area in the rooftop and the penthouse that is good for planting measures 323 square meters.

In 2008 PRRM was able to completely install a system of waste segregation on every floor that separates garbage unto four categories, namely: (1) non-biodegradable; (2) recyclable; (3) biodegradable; and (4) compostable.

In early 2009, the PRRM canteen started to be managed by an organic kitchen that could provide more than enough food materials for compost. The kitchen, called Doc Susan’s Kitchen Clinic, is run by the team of Dr. Susan Balingit who also heads the Sandiwaan Center for Responsible Health Care, Inc. Consistent with their advocacy, they provide organic food products for the people in the building coupled with their active campaign for healthy food habits. This provides the garden not only with an abundant source of food materials for compost but also clean and organically grown food.

Challenges Faced

Weight. Roof tops are built to carry the weight of only the ceiling of the top floor. In the case of the PRRM building, the iron bars used were smaller than those used at the penthouse (5th floor).

Structural designs had to be dug up and consultations with the architects and engineers are ongoing. Until now it has not yet been determined how much weight the roof top can actually carry. With this information gap, the project had to slow down while waiting for this important information from the engineers.

As of July 8, 2009 about 30% of the entire area is now filled with plants. They are grown in different containers ranging from black plastic plant bags to old and worn out vehicle tires, and directly on the ground with a thin layer of plastic film. The total estimated weight of all the materials is now eleven (11) tons.

Sunlight. At the roof top area, there is very strong sunlight coupled with a constant wind blowing. This dries up the garden very quickly. We corrected this problem by fixing a shade made of fish nets to dampen the strong light. They also have to be fixed on strong frames of metal poles that are then fixed on metal posts resting on cement-filled vehicle tires. The nets, however, now stand strong and provide shade to the plants.

The nets were supposed to go up during the peak of the summer months. With some considerable delays, the garden beds were finally installed in the first week of May which also marked the end of the summer months. On hind sight, an option would have been to use nets with bigger mesh of at least one inch. Aside from being cheaper, they will also accommodate climbing plants that will eventually give shade to the garden all the way until the coming summer months.

Drainage. With an assortment of gardening materials, there is a risk of clogging the drainage pipes. Among the materials used, it is the coconut fiber and leaves that clog the inlet pipe easily. The rest of the materials are much smaller and soluble, thus going into the drain with ease.

One design that was tried was a perforated mineral water bottle that was filled with coconut fiber that acts as filter. It was used at the corner portion of the garden to receive the water that runs under the garden beds. The garden bed is now permanently resting on the ground and the filter will stay there until such time that flooding occurs. The filter was made to stick out of the bed to facilitate fixing if necessary. As of this writing, no flooding has been observed on this portion of the garden; thus, it was easy to conclude that the filter was effective.

The rest of the drainage receptacles remain open. They have to be cleaned regularly to take off clogging debris. To facilitate cleaning, we tried using pebbles to act as filter. The pebbles, as well as broken pieces of jars are effective in allowing faster exit of the rain water as well as trapping debris such as fibers and leaves.

The latest design we tried was a cylinder of wire mesh wrapped with fine fish nets. It was effective in creating a bigger area for the rain water to pass through while holding off the debris.

Over-abundant supply of food materials. The combined operations of the kitchen and the segregation of garbage require a regular and diligent composting of the materials; otherwise, they would stink and attract unwanted insects. Two compost boxes are now installed. The first one had to be turned into a plant box while the second one still receives food scraps.

The other feature is a vermi-composting box installed last July 16, 2009 with the help of Mr. Wilfedo Benosa, a farmer technician of the RINCOMESA from Baao, Camarines Sur. Manong Willy brought one kilogram of the African night crawler (eudrilus euginae) as starter stock. The box is made of plastic sheets formed as a box with floor tiles that stand against the potted plants. The entire box rests on a mound of coco chips. The idea was to elevate the entire box to allow collection of vermi tea. This liquid is a very rich kind of fertilizer which can be diluted to become a foliar fertilizer.

Fixed Garden Beds

The fixed garden beds is my innovation that will enable gardeners to plant directly unto the ground without the use of any containers. The purpose of this innovation is to cut down the cost as well as integrate the plants unto one another by allowing them to grow freely. However, with fixed garden beds, there are several challenges.

First, the bed should not get in contact directly with the cement. Any small crack on the cement floor might cause an accumulation of debris and algae. They may also become an entry point for plant roots that may enlarge the cracks further.

For this fixed bed, we used the following materials: plastic film (caps and ends of mineral water), and broken jars and pebbles, three layers of cardboard, potting mix. Coco chips that served as foot paths were laid directly on the plastic sheet.


The fixed garden beds are designed to accommodate easy access while having the maximum number and diversity of plants. Inspired by perma-culture, the foot paths are in the shape of keyholes thus allowing the person to reach every part of the garden with ease. Taller plants are located at the farther end of the beds while smaller plants are located nearest to the foot paths.


Considerations in choosing the containers to use are cost, accessibility, weight, safety and durability. The rest of the plants are grown on an assortment of containers such as black plastic bags, rice bags (sako), wire mesh and clay pots. Rice bags are expected to last for only six months, while the black plastic bags for only a year or less. Among these containers, the clay pot is still the ideal container. It is does not contain any traces of toxic elements and it regulates the moisture of the soil. However, clay pots are heavier and more costly. Old vehicle tires that served as footing for the posts were also used. They contain, however, cadmium which may be dissolved with the potting mix in time. I planted some ginger on them but had to provide an insulating layer of cardboard between the tires and the potting mix.

The cylindrical wire mesh is another novel design for container gardens. I used a meter of the wire mesh formed unto a cylinder and filled with potting mix to plant granada (pomegranate). I will try the same size to plant papaya and lemon.


The roof top garden is now teeming with vegetables and herbs. Please see the list. We also dared to plant mulberry, tamarind and avocado on rice bags. They are not meant to grow until they bear fruit but only to harvest the leaves. Tamarind will provide seasoning for soups while mulberry and avocado will provide leaves for tea.

The Growing Medium

We only used a very little amount of soil, left from the past gardening project. I would declare that 95% of this garden uses a mixture of coco peat, carbonized rice hull (CRH) and compost. In the beginning, we had to get our organic fertilizer all the way from Nueva Ecija. The farmers of Barangay Balbalungao supplied us with fifty (50) bags of organic fertilizer and carbonized rice hull which we mixed with coco peat in 1:2:2 ratio. Coco peat holds the water, CRH serves as the habitat of beneficial microorganisms as well as drainage while the fertilizer provides the plant food.

Potting mix is water soluble. This will eventually be taken up and dissolved by the plants or go down the drain. It is therefore a must that a scoop full of potting mix be dropped on the plants, in my best estimate once during the flowering period and once after harvest and before the next seeds are sown on the same container.

Compost. I find the compost from the canteen even more invigorating to the plants. Kitchen wastes are composted immediately at the compost box and are dropped off to the plants as soon as they have matured.

On July 7, 2009 we bought a pair of guinea pigs from a pet shop. Aside from providing pleasure and being animals for affection, they are meant to eat vegetable scraps in order to harvest manure for the compost. Still, vermi-composting would be the best technology there is and we are working to have it established in the garden.

The Kitchen—Garden Interaction

A cycle is now emerging to become a beautiful rhythm of garden and kitchen. This project is also blessed with a team of advocates of healthy cooking and food habits. The kitchen crew is more than happy to participate in managing the kitchen waste, making compost, planting at their own spot, providing seeds and harvesting vegetables and herbs.

Gardening as a Team Building Activity

Volunteer gardeners among the PRRM staff are more than happy to join the gardening days of Fridays. Headed by Ms. Goyi Solis, the Director of Corporate Affairs and Human Resources, they happily make the garden beds amidst exchanges of jokes and laughter.


The project has clearly shown that the success of a rooftop garden rests on the elements of waste management, local resource mobilization, a strong cooperation with the kitchen and a strong team spirit.

It is still unclear if the project is making a cash profit. I also am not certain how and how much money it will create. However, what is clear is that it has now provided some harvests of vegetables and herbs for the kitchen, PRRM staff and other building occupants, exercise for the participating gardeners and a place of solace for the weary office worker. Furthermore, the project was conceived not only with the purpose of becoming a business enterprise. It was conceived to generate lessons on how to utilize the wastes generated, help in cooling the building, provide food and finally become a model from which urban residents may get inspired to create their own gardens.

PRRM’s Roof Top Garden
As of 20 July 2009


  • Pechay
  • Mustasa
  • Patola
  • String beans (sitaw)
  • Lettuce
  • Eggplant (talong)
  • Okra
  • Upo
  • Sibulyino
  • Kuchay
  • Garlic (bawang)
  • Bitter gourd (ampalaya)
  • Kamote
  • Talinum
  • Kulitis
  • Saluyot


  • Basil
  • Pepper mint
  • Lemon grass (tanglad)
  • Pandan
  • Oregano
  • Rosemary
  • Cilantro
  • Parsley
  • Pepper
  • Ginger

Medicinal Plants

  • Yerba buena
  • Damong maria
  • Sambong
  • Gotu kola
  • Pansit pansitan
  • Taheebo (balbas pusa)

Shrubs, vines and trees

  • Sampaloc
  • Mulberry
  • Calamansi
  • Lemon
  • Passion fruit
  • Pomegranate (granada)


  • Yellow bells
  • Sampaguita
  • Dama de noche
  • Rosal


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