How Vertical Farms Work: Technology Behind Indoor Farming

Last updated: March 28, 2026

Table of contents

1. The LED lighting: it’s not just purple for aesthetics
2. How the plants actually grow (no soil required)
3. Climate control: where the real precision happens
4. The sensors and software running the show
5. Where AI and machine learning fit in
6. From seed to salad: what the growing process actually looks like
7. The numbers that matter: how vertical farms compare
8. So why isn’t everything grown this way?
9. FAQ
10. The future is stacked (literally)

Ok wait, here’s something that caught me completely off guard. A single vertical farm in Compton, California — run by a company called Plenty — produces about 4.5 million pounds of leafy greens per year inside one building. That’s roughly 2,250 tons of lettuce from a space you could fit inside a Costco parking lot. No soil. No sun. Just stacked shelves of lettuce growing under LED lights in a climate-controlled room, harvested by robots. And the whole operation uses roughly 95% less water than a conventional outdoor farm growing the same crops. I read that and had to sit with it for a second. If you’re exploring modern urban farming methods, vertical farms are where the technology gets truly wild.

A vertical farm is an indoor agricultural facility that grows crops in vertically stacked layers using controlled-environment agriculture (CEA) technology — including LED lighting tuned to specific wavelengths, hydroponic or aeroponic growing systems, automated climate control, and increasingly, artificial intelligence — to produce food year-round without soil, sunlight, or pesticides.

Turns out, the technology behind these places is way more interesting than I expected. It’s not just “put some plants on shelves and add lights.” Every single variable — light color, air temperature, humidity, CO2 levels, nutrient concentration, even airflow speed — is monitored and controlled. It’s like a plant life-support system running 24/7. And the engineering behind each piece is honestly kind of beautiful. So I went through all of it, component by component, because I think you’ll find this as fascinating as I did.

The LED lighting: it’s not just purple for aesthetics

The first thing you notice in any vertical farm is the light. Rows and rows of glowing purple, pink, and sometimes white LEDs. It looks like a nightclub for lettuce. But here’s the thing — that specific color is doing real work.

Plants don’t use all wavelengths of sunlight equally. They’re hungriest for red light (around 660 nanometers) and blue light (around 450 nanometers). Red drives photosynthesis and flowering. Blue promotes compact leaf growth and strong stems. When you mix red and blue, you get that signature purple glow you see in every vertical farm photo.

The cool thing is, LED technology lets you dial in exactly the wavelengths your crop needs. Growing leafy greens like lettuce or spinach? Crank the blue. Want to push basil to produce more essential oils? Adjust the red-to-blue ratio. Some farms like Bowery Farming in New York have developed proprietary “light recipes” — custom spectral blends optimized for each crop at each stage of growth. A seedling gets a different light mix than a plant two weeks from harvest. That’s not farming. That’s programming biology.

This matters because lighting is the biggest electricity cost in a vertical farm. According to the Association for Vertical Farming, lighting can account for 50-60% of a facility’s total energy use (let that number sink in for a second). Modern horticultural LEDs are about 50-60% more efficient than the high-pressure sodium lamps that greenhouses used a decade ago, and they produce almost no waste heat — which means less cooling needed. But energy consumption is still the Achilles heel of this whole industry, and I’m not going to pretend otherwise. More on that later.

How the plants actually grow (no soil required)

If the LEDs are the heart of a vertical farm, the growing system is the circulatory system. And there are three main approaches, each with its own personality.

Hydroponics — the workhorse

Most commercial vertical farms use hydroponics. The plants sit in inert media — rockwool cubes, clay pebbles, or sometimes just net cups — with their roots submerged in or regularly flooded by nutrient-rich water. No soil anywhere in the building.

The nutrient solution is a carefully calibrated mix of nitrogen, phosphorus, potassium, calcium, magnesium, and micronutrients dissolved in water. Think of it as a liquid multivitamin for plants. The pH is kept between 5.5 and 6.5, and the electrical conductivity (EC) — which measures nutrient concentration — is monitored constantly.

The most common hydroponic method in vertical farms is Nutrient Film Technique (NFT), where a thin stream of nutrient water flows continuously over the roots in slightly tilted channels. The roots get nutrients and oxygen simultaneously. The water that drains off the end gets recaptured, rebalanced, and recirculated. That recirculation is why hydroponic vertical farms use so much less water — almost nothing evaporates, and nothing soaks into the ground.

Aeroponics — the high-performance option

Aeroponics takes it a step further: the roots hang in open air and get misted with nutrient solution at regular intervals. No standing water at all. AeroFarms, before its restructuring, was the highest-profile company using this method at their facility in Danville, Virginia — one of the largest indoor farms in the world at over 136,000 square feet.

The advantage of aeroponics is oxygen. Roots exposed to air absorb more oxygen, which drives faster growth. AeroFarms reported growth cycles 30-50% faster than field farming for the same crops. The downside? If a misting nozzle clogs — and they do — your plants can start dying within hours. It’s the Formula 1 of growing methods. Fast, impressive, and not exactly forgiving.

Deep water culture — the simple option

DWC is the simplest: plants float on rafts with their roots dangling in aerated nutrient water. Air stones (like you’d see in a fish tank) keep the water oxygenated. It’s less common in commercial vertical farms because it takes up more horizontal space, but some facilities use it for crops that like having consistently wet roots, like certain lettuce varieties. It’s also the most popular system for home growers because it’s cheap to build and hard to mess up.

For a deeper look at how these soilless growing methods compare — including costs, water savings, and which is best for beginners — see our full breakdown of hydroponics vs. aquaponics vs. aeroponics.

Climate control: where the real precision happens

Here’s where vertical farming starts to feel more like spacecraft engineering than agriculture. The growing rooms in a commercial vertical farm are sealed environments. Temperature, humidity, CO2 concentration, and airflow are all controlled independently — and they all interact with each other in ways that matter.

Temperature typically runs between 65-75°F (18-24°C) for leafy greens, with some variation by crop. But it’s not just about the average — the difference between day temperature and night temperature (called the DIF) affects how plants grow. A bigger DIF can make stems elongate. A smaller DIF keeps plants compact. Farms program temperature curves throughout the 24-hour “day” to manipulate plant shape. They’re literally sculpting lettuce with thermostats.

Humidity sits around 60-70% in most vertical farms. Too low and the plants lose water through their leaves faster than they can absorb it. Too high and you get mold — the nightmare scenario in a dense indoor growing environment where plants are packed close together. Industrial dehumidifiers run constantly, and air circulation fans keep airflow consistent so there aren’t pockets of still, humid air where fungal spores could take hold.

And then there’s CO2. Outdoor air has about 420 parts per million of CO2. Many vertical farms enrich their growing rooms to 800-1,200 ppm — roughly double to triple ambient levels. Plants use CO2 for photosynthesis, so more CO2 (up to a point) means faster growth. CO2 enrichment combined with optimized LED lighting can increase growth rates by 20-30% compared to ambient conditions. You’re basically giving the plants a turbo button and the plants are like “yes, finally, more carbon please.”

The sensors and software running the show

So you’ve got all these variables — light spectrum, light intensity, light duration, temperature, humidity, CO2, water pH, nutrient EC, dissolved oxygen, airflow. Each one affects the others. Change the light intensity and the temperature shifts. Change the humidity and the plants’ water uptake changes, which affects nutrient concentration.

This is why modern vertical farms are basically just data centers that happen to grow plants.

Sensors throughout the facility measure everything in real time. pH and EC sensors sit in the nutrient tanks. Temperature and humidity sensors hang at multiple heights in each growing rack (because warm air rises, so the top shelf can be several degrees warmer than the bottom). CO2 sensors monitor enrichment levels. Light sensors confirm LED output matches the programmed recipe. Some farms even use computer vision cameras to monitor plant growth, catching issues like nutrient deficiency or early disease signs before a human would notice.

All of this data feeds into a central software platform — sometimes proprietary, sometimes built on commercial IoT platforms — that runs the facility’s “brain.” Companies like Bowery Farming have their own operating systems (Bowery calls theirs BoweryOS) that process millions of data points per day and automatically adjust conditions. According to Bowery, their system collects over 100 times more data points than the average commercial farm. One hundred times. That’s not incremental improvement — that’s a different sport entirely.

Where AI and machine learning fit in

Here’s the part that sent me down a rabbit hole I still haven’t fully climbed out of. All that sensor data isn’t just being monitored — it’s being learned from. Machine learning models analyze historical grow data to find patterns humans would never spot. Like: does increasing blue light by 3% during week two of a butterhead lettuce cycle produce slightly crispier leaves? Does dropping humidity by 2% on day eight reduce tip burn? These are the kinds of micro-optimizations that AI can test and validate across thousands of growing cycles.

Plenty, the San Francisco-based vertical farming company backed by SoftBank and now owned by Walmart (which acquired it in 2024), uses machine learning to optimize what they call “plant science at scale.” Their Compton facility runs hundreds of simultaneous experiments — tweaking one variable at a time across different sections of the farm — and the AI processes the results to refine growing recipes automatically. The goal is to get measurably better with every single harvest.

Some farms are also using AI for demand forecasting and harvest scheduling. Because vertical farms can precisely control growth speed, they can time their harvests to match orders. Grow faster when demand is high, slow down when it’s low. It’s like just-in-time manufacturing, except the product is alive and photosynthesizing. That sentence is wild to me every time I think about it.

Computer vision is showing up more too. Cameras in the growing rooms can detect early signs of pest pressure, nutrient deficiency (which shows up as discoloration before it’s visible to the human eye), or growth anomalies. It’s like having a thousand experienced farmers watching every plant simultaneously. Want to see some of the most impressive real-world examples? Take a look at these mind-blowing vertical farms from around the world.

From seed to salad: what the growing process actually looks like

Let’s walk through what actually happens to a seed from the moment it enters a vertical farm to the moment it becomes your lunch. Because the step-by-step is surprisingly systematic.

Step 1: Seeding

Seeds are placed into growing media — usually small rockwool plugs or foam cubes — by automated seeding machines. In large facilities, robotic arms handle this at high speed. The seeded plugs go into germination chambers with controlled warmth (around 72-75°F) and humidity (near 100%) to trigger sprouting. This takes 2-5 days depending on the crop.

Step 2: Nursery

Once seedlings emerge, they move to a nursery section with gentler lighting. The LED intensity is lower here because baby plants can’t handle full blast yet. They stay in the nursery for about 7-10 days, developing their first true leaves and a basic root system.

Step 3: Growing phase

Seedlings are transplanted (often by robotic systems) into the main growing racks. This is where the full-intensity LEDs kick in, the nutrient solution flows, and the climate control runs at peak precision. For leafy greens, this phase lasts 14-21 days. Total seed-to-harvest is typically 28-35 days for lettuce — compared to 60-90 days in a field. Half the time. Same lettuce.

Step 4: Harvest

At many modern vertical farms, harvesting is automated too. Robotic systems cut the plants, and conveyor belts move them to packaging. At Bowery Farming’s facilities, the product goes from harvest to packaged in the same building, and can be on grocery shelves within 24 hours. Compare that to field-grown lettuce, which might travel 1,500+ miles and take 7-10 days to reach your store. That’s the difference between “picked yesterday” and “picked last week in a different state.”

Step 5: Clean and reset

The growing channels are cleaned and sanitized. Fresh nutrient solution is mixed. New seedlings from the nursery slot in. And the cycle starts again. Some farms run six or more cycles per year on the same shelf space. A field farm gets one, maybe two.

The numbers that matter: how vertical farms compare

Alright, let’s talk data, because the stats on vertical farming are striking — even when you adjust for the marketing spin.

According to Grand View Research, the global vertical farming market was valued at approximately $7.98 billion in 2024 and is projected to reach around $35 billion by 2030, growing at a compound annual growth rate of about 25%. That’s not hype money — that’s Walmart, Kroger, and Whole Foods stocking vertical farm produce on their shelves because it’s fresher and more consistent than the alternative.

The USDA has also noted that controlled-environment agriculture can use up to 95% less water than conventional farming while achieving significantly higher yields per unit area. That water number comes up again and again in the research, and it makes sense once you understand that recirculating systems barely lose any water. In a field, most irrigation water evaporates, runs off, or soaks into the ground past the root zone. In a vertical farm, the only water that leaves the system is what the plants absorb and transpire — and even some of that humidity gets recaptured by dehumidifiers.

So why isn’t everything grown this way?

Energy and economics. And I think it’s important to be straight about this because a lot of vertical farming coverage glosses over the hard parts.

Sunlight is free. LED lighting is not. A commercial vertical farm’s electricity bill can be enormous — it’s consistently the single largest operating expense. A study from researchers at Cornell University found that the energy cost of producing lettuce in a vertical farm can be 5-8 times higher per kilogram than in a traditional greenhouse that uses natural sunlight. That’s not a rounding error. That’s a fundamental challenge.

This is why almost every vertical farm grows leafy greens and herbs — crops that are lightweight, high-value, perishable (so freshness matters), and fast-growing. You won’t see vertical farms growing wheat or corn anytime soon. The energy math doesn’t work for low-value staple crops that are cheap to grow outdoors.

The capital costs are steep too. Building a commercial vertical farm from scratch can cost $10-30 million depending on scale. Several high-profile companies — including AeroFarms and AppHarvest — hit financial trouble in 2023-2024, which served as a reality check for an industry that had attracted billions in investment. The technology works. The question has always been whether the economics work at scale. For a closer look at what went wrong for some of the biggest names, read our breakdown of why vertical farms go bankrupt.

But here’s where the trend line gets interesting. LED efficiency improves every year. Renewable energy is getting cheaper. Automation reduces labor costs. And consumer demand for local, pesticide-free produce keeps climbing. The farms that survived the industry’s growing pains are leaner, more efficient, and actually profitable. Bowery, Plenty (now under Walmart), and several others have found sustainable operating models. The path forward is narrower than the 2021 hype suggested, but it’s real. For a much deeper look at whether indoor farming actually pencils out, read our analysis of the economics of vertical farming.

FAQ

The future is stacked (literally)

Vertical farming isn’t going to replace the 900 million acres of conventional farmland that feeds the world. But for fresh greens, herbs, and an expanding list of high-value crops, the technology is already here and working at commercial scale. The farms are getting smarter with every harvest cycle, the LEDs keep getting more efficient, and the AI running these places is learning things about plant growth that we’ve never known before. That last part is what keeps pulling me back into this rabbit hole — we’re not just growing food indoors, we’re understanding plants at a level that outdoor farming never allowed. For a look at where this could lead, explore the possibilities of growing vegetables in skyscrapers by 2030.

Written by Lorenzo Russo — food tech nerd and founder of FoodLore. Currently growing an unreasonable amount of basil.