Ask a Question forum: Soil Moisture Meter

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Hays Kansas
pentree68
May 7, 2018 2:53 PM CST
Hello. I purchased 2 soil moisture meters (name brand was Dr Meter). I don't know what i'm doing wrong. I put the probe down into the soil after a few days and it says my plants are still at "wet" levels. i can put my hand down the same distance and its barely moist? i think it needs water but the meter says its still wet?
i thought it was a bad meter so i took the other meter out of its package and it reads the same thing! i didn't pay much for them. don't know what's going on. any suggestions from a professional gardener on soil moistue meters? i like the idea of checking before watering but this brand I'm scratching my head.
Name: Will Creed
NYC
Profess plant consultant & educator
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WillC
May 7, 2018 5:31 PM CST
Your own sense of touch and common sense are more consistently reliable than the moisture meters. They don't actually measure water content in the soil. They measure conductivity under the theory that water is an excellent conductor of electricity. That is true, but the conductivity is also affected by the soil, including its compaction and the presence of mineral salts. Thus, it can be different for different types of soil - accurate sometimes, but not others.

The worst thing about the meters is that they appear to be so scientific that they cause people to overlook their own sense of moisture and rely on the meters often with unfortunate consequences.

I suggest you return the meters and get your money back, if possible
Will Creed
Horticultural Help, NYC
www.HorticulturalHelp.com
Contact me directly at [email protected]
I now have a book available on indoor plant care
Hays Kansas
pentree68
May 8, 2018 7:05 AM CST
Will:
thanks so much for the reply. yeah-these soil moisture meters are probably too good to be true. i'll chalk it up for experience. didn't spend a lot of money on these 2 meters. and they won't take them back since they were used. thanks again.
pentree68
Name: Carol
Santa Ana, ca
Sunset zone 22, USDA zone 10 A.
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ctcarol
May 8, 2018 7:36 PM CST
Not all moisture meters are alike. I know Will doesn't have any faith in them, but I have used the same one for several years , and it works well for anything but chunky orchid mix...in spite of it being made in China. I have tried another that was supposed to measure PH as well, and it was useless. A freshly sharpened pencil or chopstick will also work if it's long enough.
Hays Kansas
pentree68
May 9, 2018 7:15 AM CST
dear CT:
what is the name brand of the moisture meter you've had luck with?
thanks
pentree68
Name: Will Creed
NYC
Profess plant consultant & educator
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WillC
May 9, 2018 1:49 PM CST
I don't doubt your positive experience, Carol. However, brand name shouldn't make any difference as long as they are all based on conductivity, which is affected by many factors other than water.

I believe there are some very expensive moisture meters that some professional growers use that may be more accurate. However, they are far too expensive for houseplant use. That said, below is some information provided by the manufacturer of an expensive ($400) moisture meter that suggests some of the problems with meters in general.

Instructions
1. Remove any obstruction to the soil that requires testing, such as surface soil, grass, leaves, pebbles, etc. If the soil is dry or contains too much fertilizer, sprinkle some water onto the soil and leave for 25-30 minutes before testing.
2. Before using the tester, be sure to thoroughly clean its metallic surface with a piece of whetting cloth. When using a brand-new tester, we advise you to insert it into the soil a few times before taking your reading. This is in order to remove any oily impurities from its metallic surface that may affect the accuracy of your soil pH or moisture reading.
3. Insert the meter directly into the soil that requires testing, embedding its metallic surface completely and tamping down the surrounding soil so that it adheres closely to the meter's metallic electrode surface.
About ten minutes after inserting the meter in the soil, the pointer will indicate the correct value of pH or moisture.
The meter may sometimes register different values depending on the soil condition, adhesion to the meter's metallic surface, moisture content, etc. Therefore it is advised you take an average of several measurements.
4. Press the white/green button and the pointer will indicate the correct moisture value.
5. After use, wipe the plates clean of soil or moisture.

Caution
1. Do not leave the metal part of the tester in the soil for too long (no longer than one hour) or it will damage the metallic surface.
2. Make sure the metallic surface is clean and dry before storing.
3. Do not use the tester near magnetic objects, and keep it away from other metallic objects.
4. Do not measure liquid. This tester is not designed for measuring liquid.
5. Do not hold the tester with fingers on the metallic surface. Fingerprints are greasy and reduce the flow of current.
Will Creed
Horticultural Help, NYC
www.HorticulturalHelp.com
Contact me directly at [email protected]
I now have a book available on indoor plant care
Name: Baja
Baja California (Zone 11b)
Cactus and Succulents Seed Starter Foliage Fan Xeriscape Container Gardener Hummingbirder
Native Plants and Wildflowers Garden Photography Region: Mexico Plant Identifier Forum moderator Plant Database Moderator
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Baja_Costero
May 9, 2018 2:40 PM CST
I bought the cheapest one I saw, like $10-15 if I remember right. I was very happy with it. Avoid the cheap combo meters that also measure pH, because that second part is never going to be accurate enough to be useful. The moisture meter is based on conductivity which is an excellent way to judge how much water is in the soil. It's not so much useful to compare a pot with one soil type to another pot with a different soil type (those differences definitely affect the reading). But for comparing the soil in one pot to itself (on different days, as a time course) the cheapest meter can be quite useful. This was how I used it. I can't say why your meter is stuck on moist but maybe it's defective.

You have to calibrate the meter's readings with something else (like your finger, for example) so that you know what "moist" and "dry" mean. Exactly like you did. The moisture in the soil is not necessarily what you imagined in your head. The meter will tell you how wet things are, in a relative sense (comparing one pot or one soil type to itself) and you can set up a pot with soil that has no plant in it if you want to see what happens over time. Do a little experiment and you will find out in short order what the useful range of your meter might be.

I like to water when the soil is dry (growing mostly succulents) and I used to use a moisture meter every once in a while to get a sense of when that would be. Then I stopped, because I no longer needed it. The meter rendered itself redundant in a sense. Plus I don't think it's all that great for the roots to be jabbed with a metal probe every week if you can avoid it. Smiling

I think some people give up on useful tools before they learn to appreciate and overcome their limitations. Try a different meter maybe but I wouldn't spend a fortune on it.
[Last edited by Baja_Costero - May 9, 2018 2:41 PM (+)]
Give a thumbs up | Quote | Post #1704317 (7)
Name: Will Creed
NYC
Profess plant consultant & educator
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WillC
May 9, 2018 3:02 PM CST
The problem with the meters is that they are very seductive in making it appear that they will take the guesswork out of watering. Most users are not going to do the necessary comparisons to be able to deal with the inconsistencies. Learn to trust your fingers and eyesight.
Will Creed
Horticultural Help, NYC
www.HorticulturalHelp.com
Contact me directly at [email protected]
I now have a book available on indoor plant care
Name: Carol
Santa Ana, ca
Sunset zone 22, USDA zone 10 A.
Charter ATP Member Bookworm Hummingbirder Lover of wildlife (Black bear badge) Orchids Region: California
Plant Identifier
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ctcarol
May 9, 2018 7:37 PM CST
Like Baja, this is a very inexpensive meter. I don't have a brand name, but it's been working for me for years...both in pots and in the ground. Since most of my plants are perennials, I need to know how deep the moisture is before I decide to water, so the finger method doesn't work . I do tend to stick with the same brand of potting soil, so that might make a difference with the pots, but the in ground is variable. It still tells me how deep the soil is moist so I know when to water what. The one I have doesn't have any buttons to push. You just poke it in the soil and it says dry, moist , or wet. As I said , it won't work on very porous/ chunky mediums like orchid bark, but it works well enough on the rest.
Name: Will Creed
NYC
Profess plant consultant & educator
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WillC
May 10, 2018 5:19 AM CST
Soil probes (www.soilsleuth.com) are very basic, indestructible and inexpensive. They allow you to sample soil at depths up to 12 inches deep. Great for plants where you need to know soil moisture deeper than your finger can probe.
Will Creed
Horticultural Help, NYC
www.HorticulturalHelp.com
Contact me directly at [email protected]
I now have a book available on indoor plant care
Name: Baja
Baja California (Zone 11b)
Cactus and Succulents Seed Starter Foliage Fan Xeriscape Container Gardener Hummingbirder
Native Plants and Wildflowers Garden Photography Region: Mexico Plant Identifier Forum moderator Plant Database Moderator
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Baja_Costero
May 10, 2018 9:43 AM CST
WillC said:Most users are not going to do the necessary comparisons to be able to deal with the inconsistencies. Learn to trust your fingers and eyesight.


Pentree is doing exactly the comparison that is required. It's not rocket science. What is so complicated about using your finger to see what a moisture meter reading means? If you trust your finger, why not trust it to tell you what the moisture meter is saying? My advice would be to learn to use tools that make your life easier. What is the old adage about blaming the tool?

The worst thing about the meters is that they appear to be so scientific that they cause people to overlook their own sense of moisture and rely on the meters often with unfortunate consequences.


This is not a problem with the meter, it's a problem with the approach.

The problem with the meters is that they are very seductive in making it appear that they will take the guesswork out of watering.


They can and they do in many cases, once you figure out what the reading means. This is a problem with expectation, not performance. To be perfectly clear: spending $400 dollars on a moisture meter is spending about $380 too much, for most home use.
[Last edited by Baja_Costero - May 10, 2018 12:31 PM (+)]
Give a thumbs up | Quote | Post #1704932 (11)
Name: Philip Becker
Fresno California (Zone 8a)
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Philipwonel
May 10, 2018 12:33 PM CST
Today's big sofictacated farmers have water meters set up, in different areas of there farm, meters send information to central computer, telling farmer, what areas need water. Some computers will even turn water on automatically to a specific area.

Homeowners, can buy smart water sprinkler timers, that won't turn on, if ground is to wet.

Go figure ???

Anything i say, could be misrepresented, or wrong.

jbl2835
May 11, 2018 5:40 AM CST
hello Pentree 68. I bought a pkg of 2 this year same brand. Mine read the opposite that was the hand didn't move at all. cleaned them stuck them in a full glass of water same thing. paid less than $10.00. I had bought 2 at walmart 12 years ago and they worked perfectly until this year.
Name: Arlene
Southold, Long Island, NY (Zone 7a)
I was one of the first 300 contributors to the plant database! Tomato Heads Dahlias Houseplants Garden Ideas: Level 1 Photo Contest Winner: 2014
Celebrating Gardening: 2015 Plant Identifier Million Pollinator Garden Challenge
pirl
May 11, 2018 6:22 AM CST
I have two, both inexpensive, and they work quite well. Here they're both in a container of coffee grounds to show they aren't acidic.
Thumb of 2018-05-11/pirl/4ae94c

Name: greene
Savannah, GA (Sunset 28) (Zone 8b)
I have no use for internet bullies!
Avid Green Pages Reviewer Keeper of Poultry Vegetable Grower Rabbit Keeper Frugal Gardener Garden Ideas: Master Level
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greene
May 11, 2018 6:44 AM CST
I was given one of the meters but with all the care and cleaning...not for me.

So now I just use a disposable wooden chopstick to check at various depths. Close enough for my needs and it keeps my fingers clean. Thumbs up
Sunset Zone 28, AHS Heat Zone 9, USDA zone 8b~"Leaf of Faith"
Name: Arlene
Southold, Long Island, NY (Zone 7a)
I was one of the first 300 contributors to the plant database! Tomato Heads Dahlias Houseplants Garden Ideas: Level 1 Photo Contest Winner: 2014
Celebrating Gardening: 2015 Plant Identifier Million Pollinator Garden Challenge
pirl
May 11, 2018 7:14 AM CST
All the care? Wipe it off. Let it dry.
Name: Will Creed
NYC
Profess plant consultant & educator
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WillC
May 12, 2018 7:39 AM CST
If you are experienced and have had success using a moisture meter, then stay with it. Otherwise, be aware of their limitations.
Will Creed
Horticultural Help, NYC
www.HorticulturalHelp.com
Contact me directly at [email protected]
I now have a book available on indoor plant care

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