Farms in cities, deserts, and space
Could lettuce grow on a roof, in a desert, or in space?
People grow food in all three places. Each one needs a different kind of farm.
Lettuce in space? I want to see that.
What you pack depends on where you go. A beach trip needs a sun hat, and snow needs mittens.
A farm is built for its place, too.
Land in a city is scarce and costly. So some farms grow up instead of out, on shelves under lights.
A farm like this is called a vertical farmA farm indoors where plants grow on shelves stacked one above another, under lights.
See it in the glossary.
- A · grow light
- B · stacked shelves
- C · pipe carrying water up
- D · tank of nutrient solution
A city farm can grow fresh food close to the people who eat it.
It uses little land and water. But its lights use lots of electricity.
Deserts get very little rain, and some are very hot.
Desert greenhouses can use shade to keep plants cool. They catch the water that drains out and use it again.
- A · shade cloth
- B · plants growing in water
- C · tank under the floor
- D · water flows back to be used again
Astronauts have grown lettuce on the International Space Station. Then they ate it.
The plants grow in a small chamber with its own lights and fan.
- A · lights
- B · plant pillow
- C · water bag and wicks
- D · fan
On Earth, extra water drips down and drains away. In space, drops float instead of falling, and water clings to things.
So one space garden uses wicks to carry water to the plants.
Your turn. Where does it belong?
Sort each card into the place it fits best.
Which place does each card fit?
Tap a card, then a bin. Or press 1, 2 or 3 on a card.
- Nothing here yet
- Nothing here yet
- Nothing here yet
Which place does each card fit?
The answer:
City
- Stacked shelves in an old building City land is scarce, so farms grow upward.
- A greenhouse on a roof A roof is unused space in a crowded city.
Desert
- Saving every drop of scarce water Deserts get very little rain.
- Keeping plants cool in fierce heat Shade helps protect plants from the desert sun.
Space
- Water that floats instead of dripping In orbit, drops of water float instead of falling.
- Fresh leaves for astronauts Fresh food adds vitamins and fun far from Earth.
Scientists are testing ways to grow food for trips to the Moon and Mars.
Far from Earth, plants could do more than feed people. They could help freshen the air, too.
Maybe you will help design one someday.
Check 1 of 3
Why do some city farms stack their plants on shelves?
Show the answer
Cities have little spare land. Right. Stacking grows more food on a small floor.
Check 2 of 3
What is the biggest problem for a desert farm?
Show the answer
Very little water. Right. So desert farms reuse every drop they can.
Check 3 of 3
What makes growing plants in space hard?
Show the answer
Water floats instead of draining down. Right. So one space garden uses wicks to carry water.
You just learned how farms are built for cities, deserts, and space.
Next up: Jobs in growing: who works in this field.
Go deeper: space gardens and city lightsOpenClose
The United States space agency, NASA, runs plant experiments on the International Space Station.
One small chamber, called Veggie, has LED lights and a fan. Plants grow in soft bags called plant pillows, filled with baked clay and slow-release fertilizer.
Wicks carry water from a wet mat into the pillows and up to the seeds.
In 2015, astronauts on the station ate red romaine lettuce they had grown there. They ate about half, and the rest went back to Earth for testing.
A larger chamber, the Advanced Plant Habitat, runs mostly on its own. It has cameras and more than 180 sensors, and a team on the ground controls it.
Most of a vertical farm’s electricity goes to its lights. Much of the rest goes to cooling the air and taking out extra moisture.
Studies agree that a vertical farm uses many times more energy than a field for the same lettuce. They disagree on how many times.
Some desert greenhouses cool the air by pulling it through wet pads. That uses water. In one Arizona study, the cooling used more water than the plants did.
Sources
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