University of Maryland Extension

Hydroponic or aquaponic urban farms

Author: 
Neith Little, Extension Agent, Urban Agriculture


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 Basil grown hydroponically in a plug floated in a foam mat on top of a tank of water, at Envista Farms at Southern Friendship Missionary Baptist Church, in Temple Hills, MD. Photo by Neith Little, UMD Extension.
Figure 3: Basil grown hydroponically in a plug floated in a foam mat on top of a tank of water, at Envista Farms at Southern Friendship Missionary Baptist Church, in Temple Hills, MD. Photo by Neith Little, UMD Extension.

Hydroponics means growing plants using water as the primary method of delivering nutrients. Hydroponic plants may be rooted in a small amount of non-soil growth medium, like a plug (Figure 3) or mat, or they may grow directly in the water.

Aquaculture is the practice of raising seafood in a defined space, for example raising fish in tanks or ponds or raising shellfish in cages in a bay.

Aquaponics is a growing practice that combines hydroponics and aquaculture, where seafood is raised in tanks and filtered waste nutrients from the seafood are used to fertilize the plants.

Hydroponic or aquaponic urban farming is done in a wide variety of ways which differ in how much natural versus artificial light is used, and how the plants are suspended in the water. Plants may be grown in high tunnels using natural light (Figure 4), in greenhouses using both natural and supplemental artificial light (Figure 5), or indoors in buildings or shipping containers using solely artificial light (Figure 6).

Common crops are microgreens, herbs, and leafy greens. A helpful analysis of the potential and limitations of artificial light is provided by a recent article by Pattison and colleagues (2018).

Greenhouse and indoor production is considered Controlled Environment Agriculture. Zero-acreage farming or vertical farming includes both production inside buildings and rooftop farming.

 Greens and fish grown aquaponically in a high tunnel using natural light, at University of the District of Columbia Food Hub, in Washington, DC. Photo by Neith Little, UMD Extension
Figure 4: Greens and fish grown aquaponically in a high tunnel using natural light, at University of the District of Columbia Food Hub, in Washington, DC.Photo by Neith Little, UMD Extension.
 Collard greens grown hydroponically using both natural and supplemental artificial light at Envista Farms at Southern Friendship Missionary Baptist Church, in Temple Hills, MD. Photo by Neith Little, UMD Extension.
Figure 5: Collard greens grown hydroponically using both natural and supplemental artificial light at Envista Farms at Southern Friendship Missionary Baptist Church,in Temple Hills, MD. Photo by Neith Little, UMD Extension.
 Basil grown hydroponically in a modified shipping container at Urban Pastoral, in Baltimore, MD. Photo by Neith Little, UMD Extension.
Figure 6: Basil grown hydroponically in a modified shipping container at Urban Pastoral, in Baltimore, MD. Photo by Neith Little, UMD Extension.

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