Skip to Content

Soil Moisture Meters for Indoor Plants: 3 Big Dangers

Some of the links in this post may be affiliate links.

Should you be using a soil moisture meter for your houseplants? After so many people using these instruments came to me complaining about their plants dying, I wanted to give you my thoughts on using moisture meters for houseplants.

I have 3 main reasons not to use soil moisture meters, and 3 things that you can do instead of using these instruments.

dangers-of-moisture-meters-for-plants

I could easily include an affiliate link and try to get you to buy various moisture meters, but I’m not going to do that. Why?

Because I would not promote something that I don’t believe in and that doesn’t work. Period. My reputation is worth more to me than that, and I would be doing a disservice to my readers!

Soil moisture meters are not only unnecessary, but they can also be very dangerous to your indoor plants!

Countless people have messaged me, both through my blog and my Instagram site (@ohiotropics), that were using moisture meters with disastrous results.

Yet they trusted them and thought that they were doing the right thing, despite their plants drooping from dehydration.

Let me give you one example of one particular case that illustrates my point very well. I wanted to share this example and then tell you what you should be doing instead of using a soil moisture meter.

The question came from a friend:

“Do you have any suggestions as to how to keep these plants from dying? I use a water meter and they haven’t needed to water them for months.”

For months! Take a look at her poor rubber plant below. It is severely dehydrated and one of the trunks appears to be completely defoliated.

dangers-of-moisture-meters-for-plants
A Ficus elastica that has suffered from its owner relying on a moisture meter

And her Aglaonema doesn’t look like it suffered quite as badly, but the plant has collapsed and and is very dehydrated.

dangers-of-moisture-meters-for-plants
A dehydrated Aglaonema resulting from using a moisture meter.

Lastly, here is another Aglaonema that suffered from using a moisture meter.

dangers-of-moisture-meters-for-plants

Why You Shouldn’t Use a Soil Moisture Meter for Indoor Plants

1. They don’t measure water content

Shockingly enough, they don’t actually measure water content!

They measure (or try to measure) conductivity. While water is a good conductor of electricity, it is not the only factor.

Depending on the composition of the soil you have, as well as the presence of various fertilizer salts that are present, you can get very different and very misleading results.

Even if it you use tap water that has is very hard, over time, minerals can build up in the soil and your moisture meter will give false readings.

If you have a very porous, chunky mix with a lot of air, such as orchid bark mixes, it will yield very awful, misleading readings.

2. Most are junk and you can’t calibrate them

Most of the soil moisture meters available on the market are just plain junk. They’re not even worth the few dollars that you spend on them.

We’ve all seen them in nurseries and hardware stores. Don’t be tempted to buy one. Most of them will give you false readings that you simply can’t trust.

why-you-shouldn't-use-moisture-meters

They may work initially when brand new (maybe), but they won’t withstand frequent use. Besides, any good piece of measuring equipment will need to be calibrated.

The simple fact that you can’t calibrate them against a known standard is troublesome. But what would you expect from something that only costs a few dollars?

3. It drives the wrong behavior

There are many factors that go into houseplant care, and using a moisture meter takes the thinking out of plant care and this can be very dangerous.

“My soil moisture meter tells me that it doesn’t need anymore water.” I’ve heard this so many times.

If your meter indicates “wet” and your soil is actually dry to the touch, you would likely be inclined to ignore your plant for a while because the meter told you so. When in fact the soil is dry and probably needs to be watered NOW!

Even if you do get a decent moisture meter, you’ll be paying a lot more money for something that that will be adding a lot of unnecessary work and that still may not be that accurate.

So what should you use instead?

How to Judge Soil Moisture for Indoor Plants

I’ll recommend 3 ways that you can check soil moisture for your plants.

1. Use your finger to feel the soil

Sorry to disappoint you, but no gadget is required for this one! A good rule of thumb in general is to wait to water until the top inch or so (more for big pots) is dry before watering again.

Simply stick your finger into the soil and feel it. Does it feel dry to the touch? If so you may need to water. Is it still slightly moist and maybe some soil is sticking to your fingers? Time to hold off watering.

This is an oversimplification though but is a good rule of thumb in most cases! Soil moisture requirements vary depending on what plant you have.

Some plants like ferns hate to dry out much at all, while succulents and some others like to dry out completely in between watering.

For most tropical foliage plants, this rule of thumb (pun intended!) works quite well. Though I tend to use my forefinger and not my thumb…

You’ll also want to visually look at the soil too. Does it look dry? Is it maybe lighter in color? Over time, you will be able to visually judge soil moisture by the color of the soil.

But use both your sense of touch and sight though to be sure.

In one case, I misjudged soil moisture because I only felt it with my finger, but the plant was placed too high to actually see if the soil is dry.

I did that once with my lipstick plant. It was hanging high up and I would reach to feel it. It felt a little cool, but I misjudged it since I couldn’t see the soil. So I kept putting off the watering.

After realizing that I hadn’t watered it in a while, the lower leaves were yellowing so I took the plant down. I could visually see that the plant was bone dry, so I promptly gave it a thorough watering.

If you don’t trust yourself, you can use the next method.

2. Use a chopstick

Take a plain old bamboo chopstick and insert it into your soil at least a couple inches deep.

Leave the chopstick there for 10-15 minutes.

Take the chopstick out and evaluate the color. If the part of the chopstick that was in the soil has darkened, it means it has absorbed water and you should wait to water again.

If there is no color change at all, you’ll probably want to water at that time.

You can also feel the soil with your finger as reassurance if you’re not sure.

3. Lift the pot

Another way to help you judge if your plant needs to be watered is to lift the pot.

You can learn to judge if your plant needs to be watered by picking up your plant and feeling the weight of the pot.

After you water your plant, pick up the pot and see how heavy it feels. Periodically lift your plant after a few days. If the soil has gone bone dry, it will feel substantially lighter. Especially if it is in a lightweight plastic pot.

Closing Comments on Watering Houseplants

  • Ditch the moisture meter.
  • Use your senses to judge soil moisture. Feel the soil, look at the color of the soil, lift your pot, or use the chopstick method. Figure out what works for you.
  • Overtime, the longer you grow plants, you will develop a good instinct and it will become second nature.

Commonly Asked Questions About Moisture Meters

Can moisture meters be wrong?

Like any instrument, quality can vary drastically. Low-end, inexpensive moisture meters are notoriously unreliable. Higher end devices can be helpful, but in the majority of cases, aren’t worth the expense and trouble.

Should you use a moisture meter?

I strongly advise against using them for your houseplants. I’ve seen too many people kill their plants by relying on a moisture meter. Use the other methods described in this post as an alternative.

Are cheap moisture meters any good?

No, they are notoriously inaccurate and should not be relied upon to judge soil moisture for your plants.

If you enjoyed this post, there is of course much more to houseplant care. It is important to know not only when to water, but HOW to water. You may enjoy the following blog posts that I wrote on watering topics:

Overwatering Houseplants: It’s Not What You Think!

Top Myths on Watering Houseplants

Watering Houseplants While Away on Vacation

If you don’t get watering quite right, it can result in a variety of symptoms. Here are two super-helpful blog posts that will help you troubleshoot your plant problems that are related to improper watering:

Are Your Plant Leaves Turning Brown and Crispy? Top 6 Reasons Why!

Why Are My Houseplant Leaves Turning Yellow – Tips to Fix!

Please do me a favor and share this post to social media because it will help me spread the Ohio Tropics houseplant care tips to the masses! Also, check out my shop on Amazon for all your houseplant care needs:

OHIO TROPICS PLANT CARE STOREFRONT

Amy

Wednesday 11th of August 2021

I just stumbled on this article while searching for the best soil meter. I’m so glad I did! You saved me 15 bucks! I am currently battling fungus gnats and as a last resort, I’ve put a layer of gravel on top of the soil in all my plants. But now I don’t have visual or finger access to the soil which is driving me nuts. Will the chopstick method alone be sufficient? With some of my plants I am able to tell by their weight but some I can’t pick up because they are too heavy. It seems like every solution I try for the fungus gnats leads to another problem!

Raffaele

Friday 13th of August 2021

You're very welcome Amy! I'll refer you to my fungus gnat blog post for treatment: https://www.ohiotropics.com/2021/01/31/killing-fungus-gnats-houseplants/

Virginia

Monday 28th of June 2021

I am new to all of this and after purchasing a Musa dwarf cavendish and 2 x Calathea plants yesterday, I ordered a moisture meter in an attempt at watering them as they need, but after reading your blog, I have since canceled the order. After reading the comments, I hope my plants will adjust nicely to the conditions in my living room (and not die). I have kept them all in their nursery pots whilst I figure out which decorative pots I can put them in that will keep them happy but also look nice. Feeling both very nervous and excited about owning living plants (i usually opt for artificial). I hope I will learn quickly how to make these plant babies thrive. Thank you for your informative and very helpful blog.

Raffaele

Monday 28th of June 2021

Hi Virginia! I'm glad you enjoyed this post, and you did the right thing by canceling that order! Good luck with your plants :-). I would also recommend getting some less finicky plants as well. There are a lot...ZZ Plant, Pothos, various Philodendron, Sansevieria (now reclassified as Dracaena). Don't be afraid to explore :-)

John

Monday 10th of May 2021

I recently planted some azaleas and rhododendrons outside, and the soil that they came with were pretty compact, near impossible to stick my fingers into. Normally the solution would be to loosen the soil, but rhodos in general grow near the top of the soil, meaning it is very dangerous to do so. What do you recommend I do in order to properly test how moist the plants are?

So far, I did plant them in a space that's significantly wider than the pots themselves, which means that I can indeed my finger into the surrounding vicinity, but not the original potted soil mix itself. Would two inches deep in the surrounding soil be a good enough measure?

I regularly water once a day, or twice if it's visibly dry (because of the sun evaporating all the water). Thanks, and an e-mail would be helpful as I don't actively check.

Raffaele

Thursday 13th of May 2021

I just sent you an email John.

Renae

Wednesday 7th of April 2021

Hi, so happy this came up in my google search on moisture meters! My question about the chopsticks is, would it work still if i left a chopstick in the soil at all times? And just pulled it out to check? Our should I stick to 10-15mins before checking? Im short on time sometimes (read awlays) and know im likely to forget :) thanks!!

Raffaele

Wednesday 7th of April 2021

Glad you enjoyed the post Renae :-). I probably wouldn't leave it in there all the time otherwise it may give you misleading results. Honestly, I would just use your finger. It's quicker and easier and you'll get a better feel (literally) for it, and over time you'll learn to be able to tell very easily.

Lisa

Saturday 13th of February 2021

Raffaele, I have ditched my moisture meter! Thank you for the wonderful advice! I am new to your blog and love your approach to gardening! Your kindness warms my heart and that means so much during these difficult times.

Raffaele

Saturday 13th of February 2021

Hi Lisa! I'm so happy that you're enjoying my blog! Thank you for your support!