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2013-09-19 14 29 47

Using Floating Hydroponics to Grow Herbs

Posted by Candice Hart - Gardening

Growing Herbs and Vegetables with Hydroponics

Last month I posted about the first passive hydroponic setup I've tested to grow herbs and vegetables indoors. This month, we'll discuss a floating hydroponic system, which is even more simple to assemble!

University of Florida Extension says it well: "The Aztecs amazed the Spanish conquistadors with their floating gardens, and now 500 years later you can impress your friends and neighbors with yours. A floating hydroponic garden is easy to build and can provide a tremendous amount of nutritious vegetables for home use, and best of all, hydroponic systems avoid many pest problems commonly associated with the soil." Sounds awesome, right!

Passive System #2- Floating Raft System

In this particular hydroponic system, instead of having the plants suspended in the plastic net pots, they are floating on a Styrofoam raft. Seeds were again started in the rockwool cubes. Holes are cut in the Styrofoam trays, just big enough to fit the rockwool cubes. I used styrofoam trays from grocery store meat, but foam insulation panels from a home store is also an inexpensive option.

The plastic container is filled with nutrient solution and the rafts are floated in the material. The container should not be clear in order to avoid algae growth. The rockwool is suspended in the nutrient solution and wicks up the solution. Supplemental lighting should then be placed within 1-2 inches of the plants and left on for 14-16 hours.

Again, the nutrient solution is changed every 2 weeks and the container is cleaned out with each changing. Ideally, weekly pH and EC readings would be taken to make sure the pH and nutrient levels are within the correct range for the plants you're growing.


  • Low plastic container with dark sides (from any home store)
  • Recycled and cleaned styrofoam trays from meat or styrofoam insulation from a home store
  • Rockwool growing medium (online from various sources or hydroponic stores)
  • Seeds (I tested lettuce, tomato, and basil)
  • Aquarium air pump (from any pet department)
  • Aquarium tubing (from any pet department)
  • Air stone (from any pet department)
  • Supplemental lighting
  • Ph test strips and EC meter

What I Learned

  • In this project I wanted to test a couple of different plants to see how they would do. Ideally though, you would grow one type of plant so that the lighting and nutrient levels could be kept consistent.
  • I used a taller sided container for the floating raft system which wasn't really necessary. A short sided container would work better and would require less water to fill.
  • Be sure to make the holes in your styrofoam not too large. If too much water sits in the stryrofoam tray, then algae can easily grow on the top of the tray as you can see in the photo.
  • So far, I have only grown the tomatoes to the foliage stage. If I wanted to get those tomatoes to bloom, I would need to switch to a nutrient solution designed for encouraging bloom and would then need to hand pollinate once flowering did start. You could avoid these extra steps by just growing foliage plants like lettuce or other herbs.
  • It really is important to keep track of your pH and EC levels. For this initial setup, I have not been monitoring my levels and so far, my plants haven't shown signs of nutrient issues. But they certainly could.
Want to learn more about Home Hydroponics? Check out this webinar recording to learn more about using hydroponics on a larger scale.

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