It's thought the only way to grow vegetables was in a garden. Well vegetables don't necessarily need soil. They can also grow in water, provided it contains the proper nutrients and fertilizers. That's called hydroponics.
This method of growing hydroponic lettuce is called deep pool floating raft technology. It sounds pretty complicated. But it's really quite simple. And it all starts in the germination area with lettuce seeds. To plant them, workers use a steel tray connected to a vacuum hose. The tray has 276 holes and the vacuum sucks the seed into each one. Next they take a foam block with corresponding holes called an oasis and position it onto the tray. A quick flip deposits a seed into each hole of the oasis. The seeds are coated in clay. Clay holds in moisture to nourish the seed, but also breaks apart easily to let the seed sprout.
On the way to the greenhouse, the seeds get their first watering. Then workers set them afloat. The pool of water is about 12 inches deep. Technicians continuously monitor and manipulate its levels of oxygen and fertilizer. That's the key to hydroponic growing. The water is never discarded, just topped off to replace what the plants drink and what evaporates.
On the first day, they water the seeds frequently. Within a couple of days, the seedlings start to appear. They water and fertilize them. By about the fourth day, there's some significant sprouting action. Again, they water and fertilize the plants.
The first leaves emerge on about the seventh day in the summer and about the eleventh day in the winter. The winter growth rate is slower because there's less sun. At this point, it's time for the first in a series of transplants. Workers transfer the lettuces from the 276 plant oases to a styrofoam board that holds more plants, 288. They set the boards afloat in the nursery zone.At about the thirteen day mark in the summer, the twenty day mark in the winter, transplant number two takes place.
This time, to a less crowded styrofoam board that holds just 72 plants. This gives the plants more light and more room to grow. Workers use a hook to avoid damaging the roots. A plant needs healthy roots to absorb water and nutrients.
The last transplant happens on about the 26th day in the summer, the 45th day in the winter. Now the lettuces go from the 72 plant board to a board that holds just 18. By now, the plants have long roots so they're harder to manipulate.
The lettuces go into the production zone. The last move before harvesting. These pools are bigger so automatic machines move the boards around.
This hydroponic system produces 500 plants per square yard, almost five times the yield of field grown lettuce. And it's safer too. There's no need here for pesticides or fungicides. And because it's all indoors, fertilizers can't contaminate the environment.
By about the 45th day in the summer, the 75th day in the winter, the lettuces are finally ready for harvesting. Workers cut off the yellow leaves at the base. Then either cut off the roots or wrap them around the stem, depending on how this crop will be sold. Then they vacuum cool each lettuce for longer shelf life.
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