In thisTechKnow episode we see how a niche group of commercial farmers in the US is growing pesticide-free produce inside industrial warehouses with the help of artificial light.
Green Sense Farms runs its vertical farm from a 2,800 square metre warehouse just outside Chicago. The farm is bathed in a pink glow - the effect of the thousands of red and blue LEDs - light-emitting diodes - which enable the plants to photosynthesise.
"We take weather out of the equation," explains Robert Colangelo, founder of Green Sense Farms. "We've created groundhog day here. Each day is consistent and it's the same, so we always get perfect plants every day."
Farming in a controlled environment means the plants grow within a certain time using 98 percent less water. At Green Sense Farms it takes about 42 days to grow a head of lettuce, which is from 3 to 17 days faster than it would take if grown in a field. Now, Green Sense is figuring out different red and blue light combinations to optimise growing other plants, such as chives or basil. 
We also visit FarmedHere, another indoor farm, which uses an aquaponics growing system: waste from tilapia, a freshwater fish kept in tanks, is broken down by natural bacteria into nitrates, which is then cycled to the leafy greens grown there as fertiliser.
"Nitrates are the most available plant foods on the planet, so the nutrient-rich water from the fish tanks, is moved on to the area of our growth systems where the plants live. The plants take the nutrients, they filter the water, and the water recirculates back to the fish," explains Paul Hardej, cofounder of FarmedHere.
The indoor farm started off using fluorescent lighting, but are making the move to LEDs. It's the first commercial indoor farm to be certified as organic by the US Department of Agriculture.
While indoor farms are a nascent, growing industry, could they ever replace traditional farming? We put that question to some of the agricultural experts who appear in this episode. 
We also head to Seattle-Tacoma International Airport to see how conservationists are utilising the surrounding open, vacant land to save wildlife and bees. The Common Acre, a bee conservation group, has gone into partnership with the airport to develop a strain of stronger bees that can survive the harsh winter.
As Bob Redmond, the executive director of Common Acre tells us, bees are crucial as they "pollinate one third of everything that humans eat". But since 2006, he says, "there's a syndrome mostly affecting commercial beekeepers in which the colonies enter a doom cycle and they can't produce enough bees to survive so those populations collapse."
Near one of the main runways are natural wetlands, which attract birds that can get caught in the engines if they fly too close to the aircraft. We see how the airport's resident wildlife biologist has come up with creative ways to scare the birds away and to trap and relocate them to a green space about 100km from the airport.