How Does a Self-Watering Planter Work? This Clever, Low-Tech Buy Can Change Your Luck With Houseplants

Caring for houseplants takes a little attention and effort. Whether this is more than you have to give, or you willingly lavish your plants with love, a self-watering planter could help keep them healthy.

Even the most diligent, green-thumbed plant parents take vacations. Or perhaps your career or busy lifestyle frequently takes you away from home? This is when houseplants can suffer, particularly if it’s not possible for someone to water them, while you're away.

Watering houseplants incorrectly, whether too little, or too much, is the biggest cause of their demise. However, a self-watering planter can regulate the amount of moisture plants take up, so they get what they need, when they need it and no more.

For pricey plants, this kind of pot is especially advantageous. “When I bought a fiddle leaf fig tree for my living room, it actually came supplied in a self-watering pot,” says Livingetc's deputy editor Hugh Metcalf. “This plant is notoriously hard to keep alive without one, and given it cost over $100, I'd be pretty sick if it died within a few months.”

So exactly how does a self-watering planter work and what are the best houseplants to use in them? Plant experts explain this clever piece of low-tech kit, and how your plants can benefit.

What are self-watering planters?

As the name suggests, self-watering planters are containers that water your plants using a reserve. "Self-watering planters are pots which take care of watering your plants so you don’t have to," explains Andrew Flynn, co-founder of self-watering plant pot brand POTR. "They're designed to take the guesswork out of caring for your plants."

How often you should water your plants varies depending on the seasons, temperature, light levels and more. So self-watering planters can be a great solution. Additionally, they're useful for anyone who spends long periods away from home or living between two properties.

 How do self-watering planters work?

All self-watering planters have a space to store water built into their design, which the plant draws from when it's thirsty. "Some use sub-irrigation, sending water directly to the plant's roots from a reservoir of water at the bottom of the planter, allowing the plant to take when it requires it," explains Ian Drummond plant expert and author of At Home with Plants, (available at Amazon).

"The reservoir in the base of the self-watering planters is connected to the soil surrounding your plant via a wicking cord," says Andrew. "The wicking cord acts like straw for the plant whenever it is thirsty. Using capillary action it supplies the plant with the moisture it needs, when it needs it."

How often do self-watering planters need filling with water?  

Self-watering planters don't completely eradicate your responsibility. The water reserves require filling on a regular basis. Although, less frequently than regular watering.

How often this needs to be done depends on the pot itself, the plant within it, and the conditions of the environment. "A POTR pot is topped up once every two to three weeks," says Andrew. "This is perfect for anyone heading off on vacation."

Most self-watering containers will sustain themselves for a similar amount of time. However, most will need topping up more regularly when caring for plants during the summer.

Some self-watering plants have a glass water reserve, so you can see when it's low. "Others have an indicator that shows if the reservoir is full, half full, or empty," adds Ian.

What plants are they best suited for?

Since all plants need water, most potted greenery will benefit from a self-watering planter. However, the best plants for bathrooms may benefit particularly well.

"Plants which love a more moist environment such as ferns are particularly well suited to a self-watering planter," notes Andrew.

"Interestingly, self-watering planters are also perfect for a number of herbs like parsley and mint, so they can be used to grow food at home too."

"The one category we would avoid using these with are succulents." says Andrew. "Think of a cactus in a desert - it doesn’t receive rain often and therefore doesn’t like being fed a regular supply of water."

Can you overwater plants with a self-watering planter?

It's unlikely you will overwater a houseplant in a self-watering planter. The water supply is kept separate from the actual plant, preventing the roots from rotting, like they could in a regular pot.

The wick used delivers the water gradually, and this can also be controlled by you as well. "You can vary the amount of water that transfers to your plant by increasing or decreasing the length of wick cord in the soil," Andrew explains. "If you’re worried about overwatering, you can start with a short length and increase it over time."

If you're looking for tips for avoiding overwatering houseplants, investing in a self-watering planter is a good step towards success.

Are there different types of self-watering planters?

Yes there are different types and styles of self-watering planters; some more attractive than others. All self-watering planters have a water reservoir. On some planters, this is elegantly concealed, so it looks like a stylish plant pot. On others, the practical elements, such as an insert or reservoir, may be visible.

"The main types of self-watering planters are wick planters, sub-irrigated planters, and unglazed terracotta planters," explains Andrew Berger, product manager at Root & Vessel. "The biggest difference between these planters is how they deliver water to plants.

"A wicking pot or planter includes a wick that plants use to get water, while a sub-irrigated planter has an insert or a reservoir that allows plants to draw water as needed via capillary action.

"An unglazed terracotta planter may also have a reservoir but relies more on its porous nature, allowing water to seep through gradually."

Lisa Eldred Steinkopf

Lisa Eldred Steinkopf, aka The Houseplant Guru, is a plant enthusiast and author of several plant care books, including Houseplants for Beginners published by Cool Springs Press.

• Wick planters - pros and cons

With a wick system, the plant draws the moisture it needs through a wick, which is placed in the soil and leads to the water reservoir, usually within the pot.

However, it is also possible to make your own makeshift self-watering system, using a piece of string and a separate vessel of water. This is useful if you’re going to be away at short notice. However, it’s not particularly pretty, so it may not work as a permanent solution.

"Acrylic string works better than cotton as it lasts longer; cotton products will rot more quickly," says Lisa Eldred Steinkopf, author, Houseplants for Beginners. "As long as the reservoir is full of water, the plant will remain moist.

"Usually this method of watering is used with a light potting medium so that the plant is not waterlogged. A very heavy soil is not appropriate for a wick-watering setup."

"Wicking planters and terracotta planters are better suited for smaller plants," says Andrew Berger.

• Sub-irrigated planters - pros and cons

These self-watering planters are generally the most attractive, with many looking like stylish plant pots, with the practical elements hidden. A concealed reservoir and sub-irrigation system, ensure the plant doesn’t sit in the water, so the roots won’t rot. Instead, the plant is able to draw up moisture when it needs it.

The pros with these pots are the aesthetics, you’ll want to buy the gorgeous styles, regardless of the self-watering feature. The cons are that you still need to remember to top the water up every few days.

However, be aware that some sub-irrigated planters may have a visible insert which shows the water level. So check before you buy, if you prefer not to see the practical parts.

"Sub-irrigated planters prevent overwatering via an overflow drain in the reservoir or insert," says Andrew. "That way you can water frequently (i.e. every few days) without ever causing waterlogging and root rot.

"For medium to large planters (indoor or outdoor), try watering once a week. You’ll quickly learn the refill frequency by observing the water level indicator (if present) or checking the soil."

• Unglazed terracotta planters - pros and cons

These self-watering planters consist of two terracotta pots. The plant and soil is in one pot, which sits in a larger outer pot with a water reservoir. The style is more rustic and chunky, so may not suit those who prefer a sleeker look. It's also best for small plants.

"Terracotta self-watering pots have a glazed reservoir with the plant potted in an unglazed or glass pot" explains Lisa. "The water then seeps through the unglazed pot, watering the plant. These are often used for African violets."

"An unglazed terracotta planter relies more on its porous nature, allowing water to seep through gradually," adds Andrew.