Self Watering Planter

Learn how to water your plantswith just string and a Ziploc® brand sandwich bag! In this project, you’ll run a string from the bag of water directly into the soil, where the plant roots will soak up the water. You’ll need to use a low container to make sure the bag rests gently on the ground. That’s it! Your plants will have a steady supply of water to keep them green and growing, without you watering them every day. The self-watering planter takes advantage of capillary action and water’s unique molecular properties. All you need to do is keep an eye on the water level in the bag and refill it when it gets low.

  1. Ages: 3 - 11

  2. <30 minutes

  3. A little messy


Materials you'll need

Step-by-step tutorial

  • Step 1

    Gather your materials.

    Photo reference of how to complete step 1

  • Step 2

    Fill your Ziploc® brand sandwich bag with one cup of water(avoid filling the bag beyond half its size). Seal the bag.

    Photo reference of how to complete step 2

  • Step 3

    Carefully use the two clothespins to attach the bag to one side of the potted plant. The bag should be upright and rest gently on the ground.

    Photo reference of how to complete step 3

  • Step 4

    Use the scissors to cut a length of string long enough to go from the bag to the pot and into the soil about 2 to 3 inches (5.1 to 7.6 cm) deep. If your pot has multiple plants, you’ll need a piece of string for each one.

    Photo reference of how to complete step 4

  • Step 5

    Tie the ends of the string(s)to paperclips (the paperclips will anchor the strings). Carefully open the bag and drop in the paperclip(s) so they sink to the bottom and rest on the ground.

    Photo reference of how to complete step 5

  • Step 6

    Use your finger to make holes about three inches deep by the roots of the plant. Pull the other end of the strings over the side of the pot and bury it in the holes. Uses your fingers to press the soil and make sure the string is taut (cut it shorter if necessary).

    Photo reference of how to complete step 6

  • Step 7

    You’ve made a self-watering planter! Make sure to refill the bag if it gets low on water.

    Photo reference of how to complete step 7

  • Learn moremagnifying icon graphic

    Capillary action describes how water moves through tiny tubes or spaces, like the fibers in string. Water molecules like to stick to each other and to other things. That’s why your finger gets wet when you dip it in water —the water molecules stick to you! In your self-watering planter, the water molecules stick to the string fibers. Because water molecules also stick to each other, the water that sticks to the fibers also pulls up its friends. The water molecules keep climbing and pulling each other up until they reach the soil, keeping your plant alive! From there, the plant’s roots also use capillary action to bring water up from the soil to the leaves.

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