(logo chiming) - [Narrator] Forget everything you know about farming, big open spaces, tractors, even soil.

After thousands of years doing things pretty much the same old way, there's a, well, growing trend in agriculture, vertical farming.

(gentle upbeat music) Every green plant needs the same few ingredients to grow, light, water, carbon dioxide, oxygen, and some assorted nutrients and minerals.

Via photosynthesis, plants use light energy plus water and carbon dioxide to make sugars using chlorophyll and other molecules.

They use those sugars along with oxygen to power their cells.

Plants also transform some of the sugars into other useful carbon-based molecules, like the tough cellulose that gives them structure.

The nutrients and minerals are vital to plant cells staying happy.

Nitrogen is used the most.

The element is incorporated into amino acids, which organisms like plants build into proteins and enzymes that make life life.

Phosphorous atoms are in ATP, the molecule cells use for energy.

Magnesium is central to chlorophyll.

Potassium catalyzes the chemical reactions that make sugars.

So where do plants get all the stuff they need?

In the wild, plants get light from the sun, water from rain and groundwater, CO2 and oxygen from the air, and nutrients and minerals from dirt.

As humans learned to farm, we supplemented some of those ingredients using technology like irrigation or spreading on fertilizers, but vertical farming takes it to a whole new level, so to speak.

Obviously, the vertical part is the first step.

Everything else stems from that.

Instead of growing plants in big horizontal fields, you grow them in racks stacked on top of each other, basically do for farming what high-rise apartment buildings did for housing.

Growing plants in towers gives you a lot more production for your footprint.

It solves other problems too.

Moving plants indoors means they're not at the mercy of weather and other environmental factors like, say, drought or smog, we don't need to convert more wilderness to extensive farmland, and it better controls runoff of fertilizers and pesticides into waterways.

Hydroponics is one way to grow plants indoors, meaning the roots sit in nutrient-rich water, no dirt.

As a bonus, that actually reduces water use.

One study found that hydroponics produced more lettuce with 90% less water.

There's also aeroponics where the roots get sprayed with a mist of that nutrient-laden water.

Aeroponics uses 70% less water than hydroponics.

However, you need more than water to grow plants indoors.

When it comes to vertical farming, the energy use can be much greater than horizontal farming.

Climate control systems, including air circulation, water pumps, and sensors, all require electricity.

And then there's lighting.

Despite many gardeners' sunny dispositions, there isn't sunlight indoors.

How you get this light can make or break the cost of the whole operation compared to regular farming.

Remember, that thar field has a free source of lighting, the sun, so many vertical farmers use artificial lights.

Traditionally, they'd use grow lights, which produce the full spectrum of visible electromagnetic radiation.

It turns out that chlorophyll mostly responds to two narrow bands of red and blue light, meaning a lot of a grow light's energy is wasted, especially from the heat they give off, which can actually hurt plants, so modern vertical farmers often use light-emitting diodes instead.

Three things make LEDs great for vertical farming.

One, they give off very little heat.

Two, they use way less energy than incandescent or fluorescent bulbs.

And three, LEDs can be engineered to put out very specific colors of light.

This means you can dial in LEDs to exactly the colors the chlorophyll likes best for the plant to grow and flourish.

There are already a few companies trying to make vertical farming work.

One uses old bomb shelters in London.

Another uses warehouses in Newark, New Jersey, where they stack plants 36 feet high and carefully monitor all the vital variables to keep the best growing conditions.

Right now, vertical farming is still more expensive than conventional agriculture, given that whole free sunlight thing, but there are other advantages to remember, like using less water.

And because vertical farms can be in cities, you burn less fossil fuels to get fresh, tasty salad greens to restaurants and grocery stores.

So who knows?

Maybe a high-rise near you will literally start to blossom.