Hydroponic gardens supply plants the nutrients they need through water. They are useful for growing fresh herbs and vegetables in small spaces, such as apartments. We have built three kinds of hydroponic gardens with varying plant growth success. These include a soda bottle with wick system, a floating raft and a windowsill garden. The soda bottle system works fairly well as a plant starter, but if the wicks are not cleaned weekly, they tend to mold and the mold kills the plants. The raft system is a good for classrooms that receive a lot of direct sunlight. The plants will grow well and the soil won’t dry up on weekends or school holidays. Algae tend to grow in raft gardens, so again it is important to clean it weekly. Finally, windowsill gardens are just a fancier way to explore hydroponics in small spaces. See “Video” on Maker Kids (www.maker-kids.org) and on Makezine for a demonstration of Hydroponic Garden building.
Varies by Type, but can include:
Cotton-Based Rope (e.g. clothesline) for Wick
Rubbermaid Storage Tub
Aquarium Air Pump and Tubing
How To Make a Soda Bottle Garden:
Cut the top off a 2-liter soda bottle leaving about 3 quarters of the body of the bottle for a water container and 1 quarter of the bottle (inverted) for a seedling starter.
Remove and drill a ¼ inch hole into the bottle cap.
Cut the cotton rope into a 4-inch wick and thread it through the bottle cap so 1 inch extends into the plant holder and 3 inches extend into the bottle.
Cut a 9 inch piece of rubber fish tank tubing that can be used as a straw for hydroponic aeration. The straw is inserted into the water container between the container and the cup. Blowing into the straw each day.
Place the inverted cup in the water container and use a hole punch to punch through both pieces on each side. You will thread a brass fastener through each hold to hold the cup in place when its filled with perlite.
Lift out the plant cup.
Fill the water container about half full with water and a half cap of liquid hydroponic plant food.
Replace the plant holder in the water container and secure with brass fasteners.
Let the holder sit in the water for 15 minutes or so until the wick is soaked with water.
Pour in about a ½ inch of perlite into the cup and nest a few seeds close to the wick (in general beans work well).
Make sure to unlock the fasteners, lift out the cup and clean the wick each week.
Optional: Wrap dark construction paper around the water container to keep light out that promotes algae growth.
How To Make a Floating Raft Garden:
Purchase plants (e.g. tomato or pepper) from a garden store. Gently remove the dirt from their roots (by shaking and soaking the roots in water).
An opaque, 20-gallon Tupperware or similar storage bin makes a good hydroponic tank.
Measure and cut a piece of Styrofoam to fit snuggly within the container. Lift it out.
Place wire gutter traps on Styrofoam and make trace around their perimeters to make cut-outs, leaving about 2 inches of space between each circle. Cut of the circles with a sharp end of scissor using a saw-like motion.
Place the plants in the wire gutter trap so the roots extend through the circle and the rest of the plant sits on top of the wire mesh.
Fit the gutter traps in place in the Styrofoam circles. Wire gutter traps, found in Home Depot, expand and contract for a snug fit.
Fill the storage bin with water. Add a capful of hydroponic nutrient solution or more as directed.
Float the raft on top of the water in the bin. Check to make sure that the plant roots are submerged, but not the plant itself.
Push the tubing from an aquarium air pump into the bin and turn it on.
If your room is well lit, you’re ready to watch your plants grow. If your room is dark, add plant grow lights above the tub. Be careful not to position them too close to the plants or they will fry.
Make sure to lift the raft out of the bin and to clean the bin each week to keep it free of algae that can attack and kill the plant.
Something Fun: Flower bulbs, like Iris, grow very well in this kind of garden. Simply position the bulb on top of the gutter trap so its bottom just brushes the water. It’s roots will grow down into the water and eventually its leaves and flowers will spring upward.
How to Make a Windowsill Hydroponic Garden:
We made the windowsill garden from the plan provided by Windowfarms.org. This was both challenging and fun, and a bit frustrating. It’s important to fill the water all the way to the top of the gallon or the water displacement won’t work and water will not move up the tubes and trickle down the plant holders.
Hydroponic Gardening for Kids – This is the Web site that informed our initial hydroponic garden design http://www.kidsgardening.org/exploring-classroom-hydroponics/simply-super-school-setups
Windowfarms – Another site that inspired our creativity http://www.windowfarms.org/buildyourown