Vertical farming, explained

How a vertical farm works#

Plants sit in trays on racks, often several metres high, in a building with no need for windows. LED lamps supply light at the colours and times the crop likes. The roots are fed with water and dissolved nutrients, in hydroponic systems, or with a fine mist, in aeroponics, rather than soil. Sensors and software watch temperature, humidity, carbon dioxide and nutrients and adjust them, so the farm behaves like a machine for growing plants.

What it is good for#

Most vertical farms grow leafy greens, herbs and some soft fruit, which are light, grow fast and sell fresh. Because the system is closed, water can be recirculated and used far more sparingly than in an open field, and crops can be grown all year, near a city, with little or no pesticide. A 2021 review in Nature Food says such systems can use less land and water than conventional agriculture.

What stands in the way#

The main limit is energy. Replacing the sun with lamps takes a great deal of electricity, which is costly and, unless it is clean, brings its own emissions. Buildings, racks and lights also cost much more than a field, and staple crops such as wheat and rice are not practical to grow this way. The same review notes that vertical farms currently produce a limited range of crops, and that wider use needs better profitability, energy efficiency, policy and consumer acceptance.

Where it is used#

• Leafy greens and herbs Fresh salads and cooking herbs grown near the shops that sell them.
• Seedlings and young plants Raising uniform plants to transplant into fields or greenhouses.
• Harsh or crowded places Producing food where land, water or climate make fields impractical.
• Research Testing how light and nutrients change a crop’s growth.

Why have some vertical farms failed?#

Several well-funded vertical-farm companies have struggled or closed in recent years. The usual causes are the ones in this guide: electricity bills, the cost of building and running the farm, and prices that shoppers would not pay. A farm can grow plants very well and still lose money.

The ones that last tend to pick high-value crops, run on cheap, clean power, automate carefully, and sell to buyers who value fresh, local, consistent produce.

Vertical farms compared with greenhouses and open fields#

A field uses free sunlight and land and grows almost every crop, but depends on weather and season. A greenhouse extends the season and protects the crop while still using the sun. A vertical farm replaces the sun with lamps and the weather with control.

The trade is predictability and low water use against energy and capital cost. For most crops and places, fields and greenhouses will stay cheaper for a long time.

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When does vertical farming make sense?#

It makes most sense where fresh produce is expensive or hard to bring in: dense cities far from growing regions, cold or dry places, and markets that pay for consistency, such as supermarkets with year-round contracts. It also suits seedlings and research. It makes less sense for staple crops, or where cheap field-grown produce is close by.

Before investing, ask what each kilo costs in electricity, what it sells for, and what happens to the economics if power prices rise.

Key terms#

Hydroponics

Growing plants with their roots in water that carries dissolved nutrients, instead of in soil.

Aeroponics

Growing plants with their roots in air, misted with a nutrient solution.

Controlled-environment agriculture

Growing crops in a building where light, temperature, humidity and air are managed.

Photoperiod

The number of hours of light a plant receives each day, which growers set to suit the crop.

See every term from every guide in the glossary

Common questions#

Is vertical farming more sustainable than field farming?

It depends. It can use much less water and land, but it uses much more electricity. The balance improves with clean power and efficient lighting.

Can vertical farms feed the world?

Not on their own. They suit fresh, leafy crops near cities. Staple crops such as wheat, rice and maize are still grown in fields.

Why is vertical-farm produce often expensive?

Because of the cost of buildings, lighting and electricity. As equipment gets cheaper and more efficient, costs are expected to fall, but not for every crop.

Sources and further reading#

Independent pages we checked while writing this guide. They are not Reinnder products, and Reinnder is not affiliated with them.

• Nature Food: Current status and future challenges in implementing and upscaling vertical farming systems (2021) (opens in a new tab)
• Nature Food: Regional conditions shape the food–energy–land nexus of low-carbon indoor farming (2022) (opens in a new tab)