Years ago, I came across a Website that promised free instructions on building a simple hydroponics garden. On the site, the author provided instructions for what I now know is called a "raft system." It involved cutting some holes in a sheet of Styrofoam, floating the Styrofoam in a container filled with water, and sticking seedlings into the holes.
 
The author's description did not include a photo, and the instructions were so simple, I had a hard time believing it could work.
 
My mind was quickly changed about a year later when I saw a picture of one in Growing Edge magazine, and I learned that this technique is actually very widespread among commercial growers, especially for the cultivation of lettuce.
 
I've since built many raft gardens, and the results have been great, but at the risk of sounding cliché, the raft garden's greatest strength is its simplicity.
 
To build this project, you will need:


Plastic container - about 1 foot by 1 foot, or bigger. A plastic tote container will work, as will an AirFarm. The container must be at least 6 inches deep.
 
Styrofoam - about ¾" thick, but slightly thicker or thinner is OK. The piece should be big enough to just fit inside the container.
 
Lettuce seeds – whatever you have on hand, black seeded simpsons do well.
 
A balanced plant food - like Miracle Grow
 
A small bowl, mug, or cup – something that holds water.
 
Air pump, air tubing, air stone – Optional but recommended.
 
An appliance timer – recommended if you are using an Air pump
 
 
Here's what to do:
 
Step One: About 5 days before you start this project, take some lettuce seeds and place them in a bowl of room temperature water. Keep the bowl in a warm place, such as on top of your refrigerator. Check the seeds daily to make sure they don't dry out. The seeds will sprout and turn into small seedling.

 
 
Step Two: Using a pair of scissors, bore out a series of holes about the width of a drinking straw. Start the holes a few inches from the edge, and space them about 4" apart.

 
 
Step Three: Fill the container with a mixture of water and plant food. If you are using Miracle Grow, use about one teaspoon per gallon of water.

We took the top off an AirFarm
to create this garden
 
Step Four: Take the seedlings with the straightest and longest roots and carefully thread them through the holes in the Styrofoam. This is the trickiest part, you want to make sure that the root makes it all the way through and sticks out a little on the other side. Use a toothpick to help you.

Seedlings ready to be threaded into the raft
 
Step Five: Carefully place the raft into the container.

 
Step Six: If you are using an air pump and timer, attach the air stone to the tubing and place it at the bottom of the tank. Run the tubing out of the tank and connect it to the pump. Set the pump to go on for 30 – 60 minutes per day.
 
Safety note: Make sure you place the pump above the garden so that water is not siphoned back into the pump when the power if off – or use a check valve.
 
 
Care and Maintenance
For care and maintenance all you have to do is keep the water topped off and make sure it gets good light, either from a sunny window, or from artificial lighting.
 
We used 25W compact florescent bulbs for each square foot of garden and had great results.
 
If the plants are growing quickly, but are looking very pale, you might want to increase the amount of plant food. If the plants are dark green and seem stunted in growth, you have probably overdone it and should dilute the solution with water.
 
Also if you are not using an air pump, you will need to take a drinking straw and blow bubbles into the water on a daily basis to replenish the water's oxygen supply. Or, you can remove the raft from the container and vigorously stir the water for a few minutes.
 
It should take you just over a month to grow a good, edible amount of lettuce. Between crops, wash out the container and Styrofoam with hot soapy water. The Styrofoam will turn dark green after several crops and will need to be replaced
 
The results…
The growth at first is slow. This is what you might see after two weeks:

 
 
A week later:

 
And then, at about week five:

 
 
I hope you enjoy this project. If you have any questions, send an email to info@microfarm.com.
 
And please, don't forget to visit the MicroFarm shop at www.microfarm.com. They sell a grow light with timer that will work well for this project if no natural sunlight is available.
 
Thanks for reading!