Use someone elses finger to calibrate your moisture meter. Ideally someone who understands what the word "moist" means in a gardening context. I have no idea what units those testers read out in, and I wouldn't trust those units anyway. The cheap ones just read arbitrary units -- 1-10, and you have to figure out what number is what you want.

those moisture meters aren't all that great from my experience, same with the ph meter/probes.. especially for the looser type potting soil. the one i had would go from zero/dry to wet simply by moving it around an inch or two.

how about using a straw? stick a straw in the soil and when you pull it out it should have a core of soil, squeeze it out of the straw and visually look at how dry or wet the the soil is.

A moisture meter will not compensate for the wrong containers and growing medium.

Never found a moisture meter that was worth much for accuracy. In fact most I have tried over the years seem to encourage over-watering. And each brand seems to be calibrated differently - no universal applies-to-all meter readings.

If the fingers don't work well then try the wooden dowel trick - stick it in for a minute and pull it out. If darkened or appears damp then no water is needed. Better yet learn to water by the feel/weight of the container or tray full of containers or by the plant appearance - the turgidity of the leaves and stems.

Dave

Using container weights to determine irrigation needs: a simple method

Addition: Moisture Meters probably work by measuring EC of the mix. So salt content will vary your readings.

Yes, that's the best reason why moisture meters don't work well. They depend on the soil conductivity, and LOTS of chemical constituents can affect that. That's the reason why those meters don't display a real measurement of moisture, but just some relative more-moist or less-moist reading. Again, to the extent your soil chemistry is pretty constant, and you really want to rely on these meters, get a finger (or dowel, or whatever) to calibrate it.

Now, container weights are a pretty solid measure, but you have to go around picking up all your containers to do the measurement. Ouch.

They only use one Rack of containers for each group of species for weight reference.

Tree Nursery Video
https://www.youtube.com/watch?v=sMNoAq9iJ80

https://www.youtube.com/watch?v=fG7e07Dk7uo

Once you get a time period between weights or test with the finger at irrigation target points. You can can get a reference without weighing in the future. Some Racks are very small with 100 to 200 cone containers per rack. In the tree nurseries they use a hardening phase with more drought stress ( Low weight Target), and low nutrients. This causes the seedlings to set buds, and enter dormancy. This is were the accurate water status comes into play, not so much for home gardens.

Oh, I get it. So if you have 100 identical containers, you just pick up one and weigh it. That tells you what to do for all of them. Of course, if your containers aren't identical, life gets hard.

After a while, you will get a feel for it and come up with a schedule.

OTOH, if your media has good drainage and the container is tall, a little more watering should not hurt. The 5-1-1 mix is the one I make and use.

If interested , go to "Container Gardening" and get info on it. Al (tapla) is the man who has developed the recipe'.