An aerial view shows Citiponics' urban farm located on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

An aerial view shows Citiponics' urban farm located on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 Citiponics Chairman Teo Hwa Kok tends to a lettuce seedling on a growing tower that is primarily made out of polyvinyl chloride (PVC) pipes at an urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

Citiponics Chairman Teo Hwa Kok tends to a lettuce seedling on a growing tower that is primarily made out of polyvinyl chloride (PVC) pipes at an urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 Citiponics Chairman Teo Hwa Kok demonstrates how a lettuce seedling can easily be transported between growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at an urban farm on the rooftop of a multi-storey carpark in a public

Citiponics Chairman Teo Hwa Kok demonstrates how a lettuce seedling can easily be transported between growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at an urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 Organic lettuces sprout from growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore April 17, 2018.

Organic lettuces sprout from growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore April 17, 2018.

 Organic lettuces are seen on rows of growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

Organic lettuces are seen on rows of growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 Organic lettuces are seen on rows of growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

Organic lettuces are seen on rows of growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 Organic red spinach seedlings sprout from growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

Organic red spinach seedlings sprout from growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 Organic cilantro seedlings sprout from growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

Organic cilantro seedlings sprout from growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 Rows of organic lettuces sprout from growing towers that are primarily made out of polyvinyl chloride (PVC)  pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

Rows of organic lettuces sprout from growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 An apartment building is seen amid organic lettuces springing out of growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in wester

An apartment building is seen amid organic lettuces springing out of growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 Organic cilantro seedlings sprout from growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

Organic cilantro seedlings sprout from growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 Organic vegetables are seen on growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

Organic vegetables are seen on growing towers that are primarily made out of polyvinyl chloride (PVC) pipes at Citiponics' urban farm on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 An aerial view shows Citiponics' urban farm located on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

An aerial view shows Citiponics' urban farm located on the rooftop of a multi-storey carpark in a public housing estate in western Singapore

 Employees banter outside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

Employees banter outside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

 Aquaculture specialist Nick Goh smiles from the second level of Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

Aquaculture specialist Nick Goh smiles from the second level of Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

 An employee feeds hybrid groupers inside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

An employee feeds hybrid groupers inside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

 Employees inspect a hybrid grouper inside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

Employees inspect a hybrid grouper inside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

 An employee holds up a hybrid grouper for inspection inside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

An employee holds up a hybrid grouper for inspection inside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

 Coral trout are seen inside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

Coral trout are seen inside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

 Hybrid groupers are seen inside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

Hybrid groupers are seen inside Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

 An employee smiles while watching surveillance monitors at Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

An employee smiles while watching surveillance monitors at Apollo Aquaculture Group’s three-tiered vertical fish farm in northern Singapore

 An employee lifts up a net of prawns inside Apollo Aquaculture Group’s two-tiered vertical fish farm in northern Singapore

An employee lifts up a net of prawns inside Apollo Aquaculture Group’s two-tiered vertical fish farm in northern Singapore

 Lucky Phua, group deputy CEO of Apollo Aquaculture Group, looks on at the base level of their two-tiered vertical fish farm in northern Singapore

Lucky Phua, group deputy CEO of Apollo Aquaculture Group, looks on at the base level of their two-tiered vertical fish farm in northern Singapore

 An interior view of the base level of Apollo Aquaculture Group's two-tiered vertical fish farm in northern Singapore

An interior view of the base level of Apollo Aquaculture Group's two-tiered vertical fish farm in northern Singapore

 An interior view of the top level of Apollo Aquaculture Group’s two-tiered vertical fish farm in northern Singapore

An interior view of the top level of Apollo Aquaculture Group’s two-tiered vertical fish farm in northern Singapore