How to Test Moisture with the Soil Finger Test

Knowing when to water your plants is a constant struggle for plant owners, particularly first-time indoor plant owners.

The good news is, with a simple soil finger test, you can kiss all those problems goodbye. On top of that, you will begin to understand your plants’ requirements, how quickly they drink the water and how they respond to different temperatures.

soil finger test

Today at the Garden Bench Top, we are going to be introducing you to the finger test to measure your soils’ moisture levels.

It is a quick and easy test that anyone can do. And if you are a regular reader of our plant guides, you will know it is one of our top recommended ways of caring for your plants.

In this article, you can expect to learn:

  • a few different versions of the finger test for soil moisture,
  • when to use the soil finger test,
  • and some frequently asked questions about using the finger soil test.

So take off your gardening gloves and get ready to get your hands (or fingers) dirty.

What is the Soil Finger Test? How to Know if Your Plants Need Water

Put simply, the Soil Finger Test involves using your fingers to determine if your plant needs a top-up of water.

We can already see some readers’ cringe at the thought – yes – this will mean you will have to get your hands (or fingers) dirty.

the finger soil test involves using your fingers to see if your plant requires more water…

But, let us remind you, by purchasing your plants, you committed yourself to the responsibility of caring for them – for better or worse. And a little dirt here and there never amounted to any harm.

What are the benefits of checking your soils’ moisture levels?

If we were to sum up the biggest benefit of checking your soil moisture levels, it would be that your journey as a plant owner would be that much smoother and more rewarding.

By familiarizing yourself with your plant and the moisture levels of the soil, you will form an intimate understanding of your plant.

You will understand how much water it requires – and therefore, how often you need to water it.

You will see how your plants water needs change through each season. In particular, in the growing season, plants require more water, when compared to their dormant seasons.

You will be able to detect any issues/problems with your plant before it advances beyond repair.

All in all, you will become a responsible plant parent, and your plant will reward you with strong healthy growth.

How to Perform the Finger Soil Test

Now that you understand why the finger test for soil moisture is one of the best techniques to keep in your gardening tool belt, let’s take a look at how to accurately carry out your first test.

The Finger Soil Test (for Large Planters or Outdoor Plants)

Step 1 – Find an easily accessible spot in the soil where you can test (this should be close to the bottom of the plant, so you can test the soil immediately surrounding the roots)

soil finger test

Step 2 – Plunge your index finger deep into the soil, at least halfway down your finger. It should be easy to push your finger into the soil. If it is difficult, then the soil is likely too dry and compacted. This means you will need to water the area for consecutive days to ensure it has enough water.

Step 3 – Gently lift your finger out of the soil and examine the amount of soil that is stuck to it.

Step 4 (a) – If your finger has a lot of soil stuck to it, there is sufficient water in the soil, and you miss watering for the day. Here is an example of results showing moist soil.

soil finger test wet results

Step 4 (b) – If your finger is relatively clean, then the soil is dry and requires watering. Here is an example of results indicating the soil is dry.

soil finger test dry results

The Pinch Test (for Small Planters)

We usually opt for the pinch test (over the finger test) when we are testing the soil of indoor plants in small pots or containers. You can see in the photos of the planter we were testing, that if we plunged our finger deep into the soil, we could potentially damage the roots of the plant, as well as breaking or bending some leaves.

Damaging the plants leaves or roots makes the plant more susceptible to disease or rot, which can be detrimental to your plants’ health.

The steps in using the pinch test are:

Step 1 – Pinch some topsoil from the small pot between your thumb and index finger.

the pinch test

Step 2 – You should be able to feel if the soil is wet or dry.

Step 3 – The rest is really common sense. If it feels dry, it is time for a small top up of water. Alternatively, if you feel some moisture, leave watering for another day.

pinch test results

The reason why we say to top up only a small amount of water is because we are only testing the top layer of the soil. The soil further down could still be moist. Plus, the plant is in a small container, so it will only require a small volume of water to fully replenish the soil.

Soil Finger Test Additional Notes

Be sure to cover the hole created by your finger once you are finished. This helps to aerate the soil and prevent it from becoming compacted. Not to mention, a planter with dozens of holes in the soil is just plain unsightly.

We recommend getting into the habit of checking your plant’s soil on a regular basis. Simply build a regime of checking in on your plants in the morning (or every second morning) and test the soil with your finger. It is generally best practice to water in the mornings, so the plants do not sit in wet soil overnight.

Here is a short video by Healthy Planet US showing how to check the soil for outdoor plants and how to provide water to your plants.

Frequently Asked Questions (FAQ)

In this section we tackle the odd questions that may crop up while you are performing the finger test.

On a side note – if we don’t answer your question below please reach out to us via our contact page and we;’ll be sure to respond as soon as we can. We’ll even feature your question in this FAQ section so other fellow gardeners can benefit.

How far should you stick your finger into the soil when checking for moisture?

This answer depends on whether you are testing the soil for indoor plants or outdoor plants. As well as the size of your planter container (if you are checking indoor plants).

If your plants are housed in a small pot, we would recommend using the pinch test (above), since digging a finger deep into the soil may damage the root system.

On the other hand, if you are testing ground soil for outdoor plants, or indoor plants that are in larger planters, then the finger soil test will be your go-to moisture test.

How Often Should I Water My Plants?

We wish we could give you a hard and fast rule like once every week or every 4 days. However, the reality is every plant will have different watering requirements. Some prefer moist, humid conditions, whereas some plants like their soil to completely dry out in between each watering. Plants watering requirements also change depending on the season, and if it is their growing season or not.

We recommend employing the soil finger test to determine when your plants require watering. It is one of the tried and tested methods that has guided us through our years of experience. And it hasn’t failed us (yet)!

How do you Measure Soil Moisture?

If you are averse to getting your hands dirty (we know there are some of you out there), there are other gadgets that you can use to test the moisture levels in your soil. You can use Soil Moisture Meters to give you a guide to when your plants need some water. They are simple to use and easy to read. The only thing is you will most likely need a few of them around the garden.