Here’s How to Use Self-Watering Wick Cord

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Self-watering wick cord is a great way to cheat self-watering pots. You can put a reservoir in the bottom of the cache pot, and allow the cord to wick water into the soil gradually. The soil stays pretty consistently moist, but without being so wet that you end up suffocating your plant’s roots.

I have a few pots that use self-watering wick cords, and I like them a lot. There are definitely better self-watering pot mechanisms out there, but if budget is a concern, self-watering pots that utilise wicks tend to be on the cheaper end of the scale (especially compared to, say, lechuza.

How does self-watering wick work?

The cord is made out of an absorbent material – cotton is a common choice. In a self-watering pot, the ends of the cord are dipped in the water reservoir, but the majority of the cord is threaded through holes in the pot and therefore sitting in the substrate:

self watering pot diagram

It should be, er, crystal clear now.

What makes self-wicking cord so great is also kind it’s biggest issue.

You’d think that by continually wicking up the water, you’d end up overwatering the substrate BUT the wicking power just…isn’t that strong.

Many people successfully use self-watering pots with wicks for plants in leca, but personally, I don’t think it’s effective enough (you can still use the pots, just have the reservoir touch the bottom of the leca).

Can you make all plant pots self-watering with a wick?

Yeah! Just cut a couple of holes in a pot and you’re good to go! Nursery pots are a solid choice because they already have holes in them – you can make them bigger with a box cutter if required.

EXCEPT

Here I go again, ruining everything for everyone.

The bigger the pot, the less efficient the wick will be. I actually don’t buy self-watering wicking pots over about 10cm for this reason – they don’t work well enough. I may as well just water them as normal.

That being said, there’s no reason why you could add multiple wicks, and place them at different levels in the soil.

Do all self-watering pots need a wick?

Self-watering pots work by capillary action, but if the level of the reservoir is touching the plant’s substrate, then the substrate will be able to distribute the water without a wick.

Most large self-watering pots don’t use a cotton wick, because it’s just not efficient enough. Instead, they use a layer of leca or pon to wick the water up to the soil, which then wicks up the water. The barrier of leca/pon between the water and the soil (theoretically) prevents the water from becoming too soggy.

What are the benefits of using a self-watering wick?

  • Self-watering wicking systems are easy to use

They’re super easy to DIY, especially if you have those IKEA planters with the ledge inside:

she grubby

You can just add a string to a nursery pot, put a water reservoir in the bottom, set the nursery pot in the cache pot and boom, you have a self-watering wicking system.

  • Self-watering wicking systems are fairly efficient

As I mentioned, they’re not great in large pots, but they work great in smaller ones. I like these T4U ones you can get from Amazon:

self-watering wicking system
the roots growing into the reservoir is inevitable, and rarely an issue
  • They’re great if you’re away a lot

The length of time soil will remain damp with a self-watering wicking system varies greatly. It depends on the all usual factors:

  • light
  • heat
  • humidity
  • the size of the plant/pot/reservoir
  • there are probs others

However, a plant in a pot with a self-watering wicking system will still stay moist for longer than one without one, so if you’re going away for a few weeks or go away regularly and it’s gonna hot, then it’s a great option for you.

I tend to just shift all my plants into the coolest room and cross my fingers. Or leave them as they are and cross my fingers AND toes.

What are the problems with using a self-watering wick?

  • they get manky pretty quickly

As in, they get all slimy and covered in algae and generally grim.

This is really a problem in that it doesn’t do any damage to the plants, but it’s the kind of thing that REALLY bothers some people.

I’m not one of them – I’m very ‘out of sight, out of mind’ – so my self-watering pots are usually a lovely forest green on the inside. I like it! It’s nature!

Obviously you can replace them if you wish, but that seems like a lot of hassle – self-watering pots are meant to ake your life easier, not harder.

  • They have limited effectiveness

We’ve covered this. In short, they don’t work very well in a big pot.

What’s the best rope for wicking water?

I like to use cotton ones because it’s pretty efficient.

Cotton is usually conceded as the best material, BUT a lot of people then say that the downside is that it rots away quickly.

This isn’t really a concern. Sure, it won’t last forever but it will last for several years. You’re gonna be repotting your plants somewhere in that time so just swap it out for a new one once yours starts looking a bit… disintegrate-y.

Do you need to seal the ends of the self-watering wick rope?

This, along with leaving cuttings to callus, is something that people either do religiously or have literally never heard of.

I like setting fire to things as much as the next person, but I don’t think that sealing the ends of a rope with a lighter will dramatically benefit how much water it can absorb.

The argument here is that sealing the ends will reduce the chance of pests/bacteria getting the rope, but…I just don’t see how it would make a difference. If you were sealing the whole thing, fine, but just the ends? Nah.

How far will water wick up a rope?

Science claims four inches, so you need there to be less than four inches between the reservoir and the substrate.

However, you should still be able to add multiple strings at different levels if you need a wicking system for a big pot, because the wick will be able to absorb water from the soil.

There just can’t be more than a four-inch gap between a source of moisture and wherever the string is meant to be watering.

(this multiple-string method is fine in theory, but I just feel that it won’t really work in practice, but also can’t really be bothered to try it out myself. One day perhaps!)

I once read an article about how you can fill the sink with water and run strings into all your plant pots so they stay watered whilst you’re away. The four-inch rule dictates that this was rubbish, and will not work.

Final thoughts

Self-watering wicking systems are great for small pots with very absorbant substrates. I use them with one of my plants in leca – a small Philodendron golden dragon – and I used to keep my begonia in one.

It’s…fine. My plants didn’t suffer or anything BUT I don’t feel that it’s as effective as using either soil and a wicking system, or leca but having the reservoir reach a third of the way up the leca (like you would with a *traditional* leca setup.

It might work for plants that like to stay dry, like cacti, but you can’t be relied upon to remember to water them.

Caroline Cocker

Caroline is the founder and writer (and plant keeper) of Planet Houseplant

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