A Day in a Vertical Farm: How Lettuce Grows Without the Sun

In a vertical farm, there is no time when the sun rises and sets. Instead, there is a time when the lights turn on and off. In a cultivation room without a single window, lettuce grows according to the day and night that people have set for it.

From the outside, it may look like nothing more than rows of green leaves on shelves, but that day is woven together more tightly than you might expect.

Light: LEDs Instead of the Sun

The light crops use for photosynthesis falls mainly in the red and blue wavelength bands. The LEDs in a vertical farm are designed around these wavelengths, and how many hours a day they stay on is also set to match the crop and its growth stage. There is no losing a whole week to cloudy weather.

Water and Nutrients: Nutrient Solution Instead of Soil

The roots grow not in soil but in water with nutrients dissolved in it — nutrient solution. Its concentration (EC) and acidity (pH) are measured continuously, and only as much as needed is replenished. Leftover solution is filtered and reused, so growing the same amount of vegetables takes far less water than open-field farming.

Air: Temperature, Humidity, and Carbon Dioxide

For leaves to grow well, air matters just as much as light and water. If temperature or humidity drifts even slightly off, leaf tips burn or growth slows down. That is why sensors continuously measure the air in the cultivation room, and HVAC equipment adjusts it to the target values.

A good vertical farm is not one that has a special day, but one that repeats the same day as yesterday, precisely, every single day.

The Day That Data Leaves Behind

All of these conditions are kept as records. As the data accumulates on which light, which nutrient solution, and which air produced the best-growing leaves, the next growing cycle starts from those records. This is exactly why N.THING gathers cultivation data and works to control the growing environment with N.FARM.AI.

In the next post, we'll talk in a bit more detail about which values we actually look at on the Icheon farm, and how we make decisions based on them.