In an industrial section of Boston, on the roof of an abandoned bowling alley, you’ll find a vast, crystalline greenhouse where an absolute abundance of produce is being produced, all under the watchful eye of computers.
This facility, called Gotham Greens, claims to be the first commercial hydroponic operation of this type in the US to be operated in an urban setting.
The first lettuce seedlings were started back in May 2011, and the operation is expected to have delivered 100 tons of produce by their first anniversary. That may seem just a drop in the bucket when compared to the more than one-million tons that is brought into the city annually, and is in fact less production than from other area rooftop farms (which use soil rather than hydroponics) but the fact is that Gotham is barely able to meet the demand from top restaurants and gourmet markets, and they’re looking to expand another more than 940 square feet.
The work starts with the germination of seeds – a variety of lettuce and basil – in plastic containers.
Bases created from basalt are used to siphon water to the roots while providing a growth medium. About 2 weeks after planting, the new seedlings are placed into hydroponic gutters, where pumps and drains carry water packed with nutrients through the channels to the roots. At Gotham Greens, they use a technique called a nutrient film, which moves a very shallow stream of water to the roots allowing them receive plenty of oxygen. This gives the growers complete control over the quality of their produce. According to greenhouse managers, this prevents the watery, washed out flavour that some hydroponic vegetables and fruits can have. Water, oxygen, carbon dioxide, nitrogen, phosphorous and sulphur are what seedlings need for optimum growth, and most of that is available in tap water and fresh air. Any trace nutrients that are missing are supplied with a nutrient mix that’s kept in giant buckets.
When the computerized sensors or soil samples show low levels, the nutrient wash is moved into a small pond and then delivered into the watering channels. Any runoff is recycled back into the pond. To keep costs manageable, the irrigation system is kept simple. For the scale of the operation, it’s not necessary have micromanagement of the nutrients added – the water they use comes right from the tap.
One vital component of Gotham Greens’ set up is their computer-controlled system for monitoring the climate conditions and maintaining ideal temperature and humidity for the growing vegetables.
Fans, sun shades, vents, growing lights and heaters are all controlled electronically, depending on the conditions both inside and out of the greenhouse. And for pest control, Gotham Greens stays away from pesticides and instead does things the natural way. Sticky glue traps catch any insect pests that wander into the growing area. The traps are checked daily and if a veggie eating critter is found, natural predators are released into the greenhouse. For example, ladybugs purchased online are used to fight aphids which attack the tender seedlings. A tray of 1000 of the polka-dotted beetles costs about $20, which is a bit more costly than pesticides – but does the job with no harmful additives. For other pests, workers introduced predatory wasps to protect the plants.
Of course, even an organically run greenhouse needs power to run all those computers, sensors, lamps and water pumps.
To that end, they’ve installed a series of solar panels – enough to power 12 homes. A significant amount of power is expected to be generated over the upcoming summer months, and managers say they’ll be tracking that data to see the difference in electrical needs. This is the first in a long line of these sustainable greenhouses planned by Gotham Greens, and we wish them all the best!
Image credit – Gothamgreens.com
Jim works for RJ Herbert, specialists in root crop processing and vegetable handling systems. He is a keen advocate of carbon neutral and sustainable growing, and loves finding out about new methods and operations.