So basically you build your hydroponics basins setup as normal. For an optimal use of space that the artifical sun shines on use this pic:



Now you just let your people plant something in them. For Example Potatos. Immedeatly after they planted them, change the plant type to something else like Rice. When the Previous plant hasn't grown already they should plant the new one inside of them, meaning instead of 4 plants there are now 8 plants. If you do this too l8 however, this might not work. Im also not sure how much time you have, I just now you have a higher succes chance if u do it earlier.
It should then look like this: