How to Build a Hydroponic Propagator

Updated June 26, 2017

Hydroponic gardening provides a soilless alternative to traditional gardening. Hydroponic plants generally require much less room that those grown in soil. Small hydroponic propagators allow you to start your vegetable and herb seeds in a controlled environment that encourages healthy germination and sprouting. While many gardening suppliers and nursery centres sell hydroponic propagators, building your own can save you money.

Measure the top opening in your aquarium. Subtract 1/2 inch from the width and length. Using a ruler and pen, transfer your measurements onto a 2-inch-thick piece of polystyrene sheeting. Cut out the shape with a serrated kitchen knife.

Wash your aquarium with mild dishwashing soap and hot water. Rinse thoroughly to remove all traces of soap residue. Place the clean aquarium under a grow light. Set the aquarium aerator in the bottom of the tank and hook the tubing to your pump. Mix the concentrated hydroponic solution with lukewarm water, according to the package instructions. Fill the aquarium with the solution to a level about 3 inches below the rim. Plug in the pump and adjust the amount of airflow to disperse a thin stream of continuous bubbles into the solution.

Place the small pots upside-down on top of your piece of polystyrene. Allow at least 2 inches of space between each pot. Use a pen to trace around the shape of the rims. Cut out the traced shapes, making your cuts 1/8 inch inside the traced lines. Press the bottoms of the pots into the holes in the polystyrene, pressing down until the rims are close to level with its surface.

Fill the pots with perlite. Cut pieces of white paper towelling to fit over the surface of the perlite in each pot. Lay four to five seeds over the paper towelling. Apply a thin layer of peat moss over the tops of your seeds, making the layer about twice as deep as the diameter of your seeds. Spray the moss in each pot with water until it becomes evenly moist.

Set the pot raft over the surface of the solution in your aquarium. The solution will gradually soak into the perlite, saturating the paper towelling and peat moss around the small seeds.

Mix and add more hydroponic solution when the level in the aquarium drops about 1 in. Depending on your humidity and the rate of evaporation, you may need to fill up your aquarium every week or two. Thin your young seedlings when they develop their second set of leaves, allowing only the strongest seedling to remain in each pot.

Things You'll Need

  • Ruler
  • Pen
  • Polystyrene sheeting
  • Aquarium
  • Dish soap
  • Grow light
  • Aquarium aerator
  • Concentrated hydroponic solution
  • Aquarium pump
  • Plant pots
  • Perlite
  • Paper towels
  • Plant seeds
  • Peat moss
  • Spray bottle
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About the Author

Piper Li, a professional freelance writer, began writing in 1989. Her articles appear online at Biz Mojo, Walden University and various other websites. She is the co-editor for "Kansas Women: Focus on Health." With a bachelor's degree in journalism from Mesa State, Li enjoys writing about health, horticulture and business management.