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How Do Self-Watering Planters Work?

How Do Self-Watering Planters Work?

Have you heard of self-watering planters, but not sure how the whole “self-watering” thing works? It’s less complicated than you think.

Also known as self-wicking, self-irrigating, and auto watering pots, self-watering planters are plant pots with a built-in watering reservoir that the plant can take up water from.

The beauty of a well-designed self-watering planter is that your plant drinks only what it needs, taking the guesswork out of how much or how often to water your plants. Self-watering planters are also a great option if you travel or just have a busy schedule, because they put watering on autopilot.

If you’ve bought a self-watering planter, you may be wondering if it actually works. How can you trust that the plant will “drink” from the water reservoir on its own?

The answer is a little thing called capillary action.

Image there’s a spill on your counter, and you lay a paper towel on it. What happens? Almost immediately, the moisture miraculously spreads through the paper towel.

This occurrence can be explained by capillary action: the tendency of water to adhere to porous materials. Just as water adheres to the porous fibers of paper towels, so too does it absorb into porous soil in a self-watering system.

You may be thinking: isn’t there a possibility in a self-watering planter for the plant to drown, since there’s a constant source of water it can drink from? The answer is no, for the same reason a paper towel won’t keep absorbing water once it’s saturated. In capillary action, water is only attracted to porous materials - if the pores are filled, there’s nowhere for it to go. Once your plant drinks up what it needs from the water reservoir, the soil won’t take up water again until it’s dry.

Capillary action is so powerful that it can counteract gravity: precisely why water in a self-watering pot can travel upward to the potting soil. If you’ve ever bottom-watered your plants, self-watering planters work essentially the same way.The main difference is that with bottom watering, you eventually have to take the plant out of the water basin so it’s not sitting in the water.

With a self-watering plant pot, the potting soil and water reservoir are already separated enough that there isn’t a danger that the plant’s roots won’t get over-saturated.

How to Use a Self-Watering Planter

While self-watering planter designs vary slightly, they generally all function the same way.

Step 1: If there are two compartments to the planter, separate them 

Step 2: Starting with the component where the potting soil and plant will go: fill the pot about halfway with potting soil

Step 3: Remove your plant from its nursery pot

Step 4: Loosen the roots very gently at the bottom, so that a couple tendrils poke out

Step 5: Gently place your plant into the pot

Step 6: Fill in the empty spaces around your plant with more soil, so that it’s filled almost to the top

Step 7: Water your plant from the top, to make sure the soil gets saturated through

Step 8: Place the pot with the plant on top of the water reservoir container

Step 9: Wait until the soil dries out again (use the finger test - check for moisture two knuckles deep) before filling the water reservoir with water.

Voilà! You’ve put together your self-watering planter so your plant can start drinking away. Your plant will soak up water from the bottom, so as long as the reservoir stays filled, your plant will get a consistent level of moisture. 

Best Indoor Plants for Self-Watering Pots

Most indoor plants tend to have tropical origins, preferring moist conditions. This makes most houseplants suitable for self-watering pots. Some indoor plants that particularly thrive in self-watering planters:

  • Spider plant
  • Philodendrons
  • Bromeliad
  • Peace lily
  • Ferns
  • Pothos

Some plants that may not react as well to self-watering planters are succulents and orchids, as they prefer to have soil completely dry out in between waterings. Otherwise, self-watering planters are a great option for anyone who wants to have reliable watering for their plants.


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