How to Make a Micro Self-Watering Wick System from Styrofoam Cups

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Styrofoam Wick System

Styrofoam Wick System inside bottom


This is a very small scale version of other self-watering wick systems similar to Earth Boxes. This tiny very I will describe uses the exact same principles as the EarthBox, and can be easily scaled up. It is very easy and inexpensive to make. You can use mostly (or entirely if you get creative) recycled materials. The system in my example here is ideal for plants ranging from spouts or seedlings up to small plants that will fit in a 20 ounce cup (for this example). The plant and supporting medium (potting mix, coco fiber, etc…) will sit at top of the cup inside a 3 inch net pot. A strip of wicking material will touch the supporting medium and affix to the bottom of the net pot. It will hang down and wick nutrient solution up from the bottom to the plant. The plant will draw water/nutrients as it needs. Once it is setup, the grower will need to fill the reservoir as needed.

Materials Needed

  • 2 x 20oz Styrofoam cups
  • 1 x 3 inch net pot
  • Potting mix (or similar) enough to fill the net pot and upper part of the Styrofoam cup
  • A 1/4″ – 1/2″ wide strip of wicking cloth a little less than the length of one of the cups. Strips of microfiber cloth worth really well. Just test a piece first by holding the end in some water and see if it wicks up to the top.
  • Knife
  • Nutrient solution – Mix to a strength appropriate for the plant. To start with, use something no stronger that what the plant was in previously.


  1. Cut the inside bottom out of one of the Styrofoam cups.
  2. Tie one end of the wick cloth to the bottom of the net pot, making sure some of the cloth is exposed to the inside of the net pot.
  3. Push the net pot down into the top of the cup that you cut the bottom out of.
  4. Determine the distance from the bottom of the net pot and bottom of the Styrofoam cup that it is in. Then add to it the offset between the bottom of the two cups when one is placed inside the other.
  5. Make a mark of the combined lengths on the outside cup (one that doesn’t have the bottom cut out) from the bottom. Then make a mark below that about 1/2″. This second line (lowest one) is your max fill line. This will allow an air gap between the bottom of the net pot and the top of the nutrient solution. If the nutrient solution is too high and touches the net pot, the plant will drown.
  6. Transplant your seedling or small plant into the top of the inside cup and make sure to water it in.
  7. Fill the bottom cup with nutrient solution up to the max fill line determined above.
  8. Place the cup that contains the plant and wick into the cup that has the nutrient solution, making sure the wick hangs down into the solution.
  9. Place the plant under a grow light.


Periodically lift the inside cup out and check the nutrient level, adding more as needed. As the plant grows it will consume at a faster rate, so you’ll need to check and fill more frequently. You could optionally place the inside cup or cups into a tray and fill up to the max fill line. You’ll just need to make a few small holes in the bottom of the plant cup up to the fill line so that nutrient solution that’s in the tray can enter. If you use this method you won’t need the bottom cup.


As soon in my video, you can use other materials to craft small self-watering wick systems.  One example is a large 32 ounce cup with holes make in the lower portion and wick attached. This is placed in a 20 ounce up, and it leaves plenty of room for nutrients. Another example is a plastic ocean spray bottle cut in half with holes drilled in the nozzle end and in the cap. Wick is tied through the cap and this is inverted into the lower part of the bottle. The point is you can be creative and use what you already have if you don’t have the exact materials mentioned above. All of these examples make excellent and effective wicking systems.


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2 Replies to “How to Make a Micro Self-Watering Wick System from Styrofoam Cups”

  1. Hi Peter. In your video, I see some of your cups have drinking straws in them. What are those for? I’m new to gardening so I’d like to learn the use for those. Thanks and I enjoy your videos.

    1. Thanks for asking. I think that was an early version I worked on attempting to provide a fill hole. I found it was easier to just lift it up and add more nutrients.

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