Testing The Waters: How Floating Gardens Could Solve Our Biggest Environmental Challenges

Floating gardens are having a renaissance. Faced with the realities of climate change, this centuries-old technique is being adapted in different parts of the world to solve twenty-first century challenges.

The first floating gardens were built hundreds of years ago in Mexico and can still be enjoyed today (in part thanks their UNESCO World Heritage Site status).

Just outside Mexico City are the canals of Xochimilco, the Aztec word for “where the flowers grow”. Between the eighth and tenth centuries, the Xochimilca people settled in the Valley of Mexico, an area composed mostly wetlands where traditional farming practices proved ineffective. Taking advantage of the rich nutrients the wetlands provided, however, the Xochimilca people built containers (chinampas) and secured them to trees along the shoreline, growing fruits, vegetables, and flowers.

Eventually, the Xochimilca people were conquered by the Aztecs, who implemented the floating garden technique to sustain their immense empire. It is estimated that these floating gardens at one point covered 22,000 acres of wetlands and fed tens of thousands of people. Unfortunately, only a few of these floating gardens remain, protected in the Parque Natural Xochimilco, where they are a habitat for many endangered species.

Balmori Associates, Inc.

Today, floating gardens are remedying the problems of the past. Situated in southern Brooklyn, the Gowanus Canal is widely considered one of the most polluted sites in the United States. Initially known as Gowanus Creek, the original saltwater marshlands were first expanded in 1664 and again in 1849 to form a canal in support of the growing industry along the waterfront. As an international hub for commercial shipping, factories (including tanneries and chemical plants) quickly crowded the area, polluting the water and air–the effects of which are still felt today.

Floating gardens on display in Regent’s Park, London, as part of the 2015 Chelsea Fringe (an alternative gardening festival).

GrowOnUs, a project developed by Balmori Associates, aims to improve water quality in the Gowanus Canal with floating gardens. The initiative relies on a process known as phytoremediation, which employs plants to remove pollutants. On land, phytoremediation is an established technology for decontaminating soil, known to be both efficient and economical. Root systems absorb contaminants, leaving behind clean water and soil. Different plants are more or less effective–GrowOnUs uses salt marsh bulrush, fringed sedge, swamp rose mallow, and blue flag, among others. In addition to these “cleaners,” GrowOnUs has also planted “producers,” which can be used for natural dye, provide a habitat for native species, are sustenance for pollinators, and have medicinal properties. Tucked in between the plants are solar stills (which desalinate and remove heavy metals from the water) and solar lights. If this first venture proves successful, Balmori hopes to make the floating gardens a self-sustaining economic venture by growing herbs and other plants to sell to local vendors (though for now, any plants grown in the river are not safe to eat).

The Floating Gardens art installation in London’s Regent’s Park aims to create a new ecosystem for underwater vegetation and wildlife.

At this year’s Chelsea Fringe Festival– an alternative gardening festival that positions itself as the art-y antithesis of London’s iconic Chelsea Flower Show, floating gardens played a defining role. Landscape architects Michela Pasquali and Sara Di Costanzo teamed with artist Veronica Montanino to design an exhibit inside the lake at Queen Mary’s Gardens in Regent’s Park. Aimed at raising public awareness of the fact that “underwater vegetation and wildlife in urban water bodies and rivers is becoming scarce”, their FLOATING GARDENS exhibit created an archipelago of small, intriguing “islands” that improved water quality while encouraging plant biodiversity. These “floating wetlands”, which were at once colorful and intriguing to the eye, also provided food and shelter for fish, frogs, and invertebrates. They also offer shade to underwater plants, which reduces water temperatures and limits submerged weed growth.

When it comes to urban beautification and cleanup, floating gardens are an ideal solution: they rehabilitate wetlands and waters; they provide a reliable source of food and livelihood; they are sustainable and often biodegradable; and they remedy the problems of the past (pollution) while withstanding the challenges of the future (changing water levels). They are practical without being intrusive, and make healthy what was once poisoned. At a time of uncertainty and tribulation, floating gardens offer hope that we can keep our heads above water.