Answer:
He is using Hydroponics.
Step-by-step explanation:
It is hydroponics because
Hydroponics is an horticultural method of cultivating plants or growing plants without soil but by using water and nutrients or minerals solutions to cultivate the plants.
Hydroponics plants or herbs are cultivated inside a growing media and necessary nutrients, oxygen and water are supplied to boost their growths.
Examples of plants cultivated using hydroponics are tomatoes, lettuce, spinach, spring onions, blueberries e.t.c.