What Is Vertical Farming and How Does It Work? Benefits and Limits for Cities

Stacked indoor farms grow leafy greens close to cities, but they have clear limits on crops, energy and cost.

Vertical farming is a way of growing food indoors in stacked layers, using hydroponics, aquaponics or other methods that do not need soil, according to the U.S. Department of Agriculture’s Agricultural Research Service (USDA ARS). This guide explains how the method works, which crops suit it, where it struggles, and what that means for city food supply.

How Vertical Farming Works

Layers, Water and Light

Instead of spreading plants across a field, a vertical farm places growing trays or racks on top of one another inside a controlled indoor space. Plants usually grow in hydroponic systems, which means their roots sit in a water-based nutrient solution rather than in soil. Aquaponics, a related approach, combines plant growing with fish farming. The USDA ARS describes all of these as soil-free methods suited to stacked indoor production.

Because there is no sunlight reaching the lower layers, the farm relies on artificial lighting and on equipment that manages temperature and humidity. The grower gains control over the environment and pays for it in electricity and equipment.

Why Land Use Drops

Stacking is where the space advantage comes from. For some crops, the USDA ARS cites yields 10 to 20 times higher per acre (a little under half a hectare) than in open fields, using far less land. The figure applies to some crops, not to farming in general.

What Vertical Farms Grow Today

Current production is concentrated in leafy greens such as lettuce. The USDA ARS explains that the best candidates grow well in hydroponics, stay compact, and can be harvested whole. Strawberries and fruiting plants such as tomatoes and peppers are still being researched, so they are not yet the backbone of indoor farms.

Grains and field crops are a different story. The USDA ARS considers cereals and row crops such as corn, rice, wheat and soybeans better suited to traditional agriculture. In practical terms, it does not replace basic staple calories. It adds a local source of fresh, perishable produce.

Quick Self-Check

Look at the last grocery bag you carried home. How much of it was leafy greens or herbs, and how much was grain, oil, or meat? If most of the weight came from staples, you have just seen why indoor farms are a better fit for one corner of your plate than for the rest of it. Which of your staples could ever come from a building down the street?

The Limits That Matter

Energy and Equipment

The USDA ARS names the central limit plainly: without free sunlight, the system depends on artificial light, which can become expensive. Humidity control also requires costly air handling equipment (HVAC) that uses a lot of energy. A reliable per-kilogram energy figure from a primary source was not available for this article, so no average is quoted here.

Cost Compared With Open Fields

A publication from the Federal Reserve Bank of Richmond cites a 2019 estimate that producing food in a greenhouse or vertical farm costs three to five times more than producing it in a field. Treat that as an estimate from a secondary source rather than a measured price, since costs vary by crop, building and energy market.

A Forecast, Not a Fact

One USDA ARS researcher has speculated that vertical farms could take roughly 50% of the U.S. leafy greens market and about 5% of the strawberry and tomato markets within ten years. This is her opinion, not an official statistic or a confirmed prediction. The USDA ARS article shows no visible publication date, so some details may have aged.

Food Safety Rules in the United States

The U.S. Food and Drug Administration (FDA) enforces the Produce Safety Rule under the Food Safety Modernization Act, which has been in effect since January 26, 2016. It includes exemptions, such as farms with annual produce sales of $25,000 or less, and a qualified exemption for farms with sales under $500,000 when most of the food goes directly to consumers or local buyers.

The FDA also set staggered deadlines for pre-harvest agricultural water requirements for non-sprout crops: April 7, 2025 for farms above $500,000 in sales, April 6, 2026 for farms between $250,000 and $500,000, and April 5, 2027 for farms between $25,000 and $250,000. One caution: the FDA page does not mention hydroponic or indoor farming, only greenhouses and germination chambers in a passage about facilities. No rule written specifically for vertical farms was found, so whether a given farm is covered depends on its own circumstances.

Where Vertical Farming Fits in Cities

Put together, the picture is modest but useful. Vertical farms can produce fresh greens inside or near a city, in a small footprint, which fits the planning goals discussed in our look at smart cities and technology for quality of life. Automation is a natural companion, and our article on robotics in precision agriculture covers the machines that increasingly handle planting and harvesting. For the wider question of resource limits, see our piece on atmospheric water harvesting.

What the method cannot do, according to the USDA ARS, is feed a city its grains and staple crops, and it carries real energy and cost burdens. No official water-savings figure was found, so none is quoted here.

What This Means for You

If you are a shopper, vertical farming is most likely to show up as packaged lettuce, herbs and similar greens, not as a replacement for the rest of the grocery cart. If you are following the technology or considering a business in it, the sensible questions are about electricity costs, crop choice and which regulations apply to your size and sales.

Frequently Asked Questions

What is vertical farming in simple terms?

It is indoor farming in stacked layers that uses hydroponics, aquaponics or other soil-free methods, as described by the USDA ARS.

Which crops grow best in vertical farms?

Leafy greens such as lettuce are the main crop today. Strawberries, tomatoes and peppers are still in research, according to the USDA ARS.

Can vertical farms replace traditional farming?

No. The USDA ARS considers corn, rice, wheat and soybeans better suited to traditional agriculture, so vertical farming does not replace staple calories.

Why is vertical farming expensive?

Artificial lighting and humidity control equipment use a lot of energy, according to the USDA ARS. A Richmond Fed publication also cites a 2019 estimate of three to five times the cost of field production.

Are there special U.S. rules for vertical farms?

The FDA page on the Produce Safety Rule does not mention indoor or hydroponic farming. Coverage depends on the individual farm, so check with the FDA.

This content is for informational purposes only and does not constitute personalized financial advice. Terms and conditions change, so confirm the details with the official provider before making a decision.

Last reviewed: 2026-10-18

Sources consulted:

https://www.ars.usda.gov/oc/utm/vertical-farming-no-longer-a-futuristic-concept/
https://www.fda.gov/food/food-safety-modernization-act-fsma/fsma-final-rule-produce-safety
https://www.richmondfed.org/-/media/RichmondFedOrg/publications/research/econ_focus/2021/q2-3/feature1.pdf