How to choose the best pH meter for your garden?
Growing plants can be challenging if your garden soil isn’t the best. Do you live in a clay-filled area or does your backyard come with a sandy soil?
Different plants react to changes in the soil and some varieties just won’t grow at all if the nutrients and minerals are not right for them.
But have you ever checked the pH level of your soil? Knowing this magic number can help you look after your plants better or transform your blooms from wilting to wondrous.
If you’ve ever wondered how to measure the pH level of your garden soil then you might have tried shopping for a pH meter.
But with so many to choose from, which is the best? We’ve put together a great buyer’s guide so you can make sure to get the right meter for your garden.
What is pH level?
The pH scale measures the acidity or alkaline concentration of a substance. It ranges from 0 which is the most alkaline to 14 which is the highest acidity. A perfect, neutral pH level is 7.
Pure water is pH neutral but don’t be fooled into thinking the water that comes from a tap at home is perfectly neutral. There are all sorts of factors including the material in your pipes and the container you catch the water in which can affect pH levels.
You may be surprised by some acidic or alkaline substances. Milk and citrus fruit are both classed as acidic whereas eggs and ammonia are in the alkaline category.
Substances at the two extremes of the pH scale, either very alkaline or extremely acidic, are harmful and corrosive. Sulfuric and hydrochloric acid are both harmful acidic substances and caustic soda is an extreme example of an alkaline substance.
Why do plants need certain pH levels?
The majority of plants like soil to be slightly acidic rather than neutral. The most common pH level is about 6.5 to suit most plants.
Some plants, like azalea, rhododendron or blueberries need a very acidic pH level.
If you plant your shrubs or flowers in soil without the right pH level, you will see your plant start to wilt or fail. Some gardeners misunderstand this as a lack of fertiliser or water and pile this on to no avail.
Plants need a set pH level to grow properly and absorb nutrients from the ground. Although most plants want a slightly acidic soil, you can tolerate a pH neutral soil or even slightly alkaline as long as it doesn’t drop below 5.
In soil which is too acidic, your plant can get aluminium, hydrogen or manganese toxicity while at the same time not absorbing enough calcium or magnesium.
If your garden is too alkaline, then your plant won’t have enough manganese, phosphorous, zinc, copper or cobalt. A reduction in these chemicals means your plant won’t be growing as fast or as strongly as it should.
What does a pH meter do?
A pH meter gives a very accurate reading of how acidic or alkaline a soil is. It shows the pH level to 0.01 of a unit.
It shows on a scale of colours through red for very acidic to blue for very alkaline.
The instrument shows the “power of hydrogen” which is what pH stands for and measures the difference in electricity.
In acids, there are more positively charged hydrogen ions than in alkaline solutions. A pH meter measures how much electrical current this solution could provide. It tests the voltage of the solution and then compares it to a base level.
It is using this comparison that the pH meter works out the difference in pH level.
A pH meter is made from two main parts – the dial or meter which shows the result and a probe which you place into the substance you want to test.
You might think this is a modern invention but the first pH meter was created by a German chemist called Fritz Haber in 1909 with his student Zygmunt Klemensiewicz. They started becoming mass produced and released to the average scientist or gardener in 1934 when Arnold Beckman developed the idea.
The best way to use a pH meter
A pH meter is easy to use. The first thing to do when you get a new pH meter is to calibrate it and ensure it is working accurately.
Clean the probes thoroughly and then test them put dipping them into a substance you know the pH level of beforehand such as clean, distilled water.
pH meters are also affected by temperature changes so unless the device also has a built in thermometer and the ability to change the readings relating to the temperature then you need to take this into account.
You should make sure to take your readings at roughly the same temperature to get the best and most accurate results.
How to change the pH level of your soil
If you think the pH level of your soil could be why your plants are failing or producing small, bitter crops, then you need to test its level.
You shouldn’t attempt to add chemicals before you know the current pH level of soil because whether your ground is too acidic or too alkaline it will have roughly the same effect on your plants.
You should also know what type of soil you are dealing with as that will give you clues to the pH level even before you test it with a meter. Take a sample with a trowel and examine it closely. Soil can either be sandy, clay based or a mixture.
If you need to make your soil more alkaline, a good thing to add is limestone. This rock is made from pure calcium carbonate which is brilliant at reducing the acidity of your soil. If you have a clay-based soil then you will need to use more limestone because it is not as absorbent as a sandy soil.
Sulfur is used to lower a pH level and this can be spread across your soil quite easily. It isn’t water soluble so it needs to be mixed into the top six inches of your flowerbeds by hand. You can also lay the substances on top of your soil and it will gradually sink down into the ground.
Features to look for the best pH meter
There are lots of different pH meters available so how do you choose the best one? There are different features to choose from and some are better than others.
Some meters have several different functions in one device. They can measure light, moisture and temperature as well as pH levels.
However, this can make them less accurate as they are not focused on one task. If you’re looking at a meter on the cheaper end of the market then the accuracy could be affected by performing different fucntions.
Another feature you want to consider is the length of the probes themselves. Meters need to be able to be completely immersed in the soil to get the best reading so if you’re buying a meter you should make sure the testing prongs are large enough for this.
But you don’t want a meter that sticks out of the ground too far as if you’re trying to test the soil right underneath a thick bush or plant you might find it won’t fit and you will have to put the meter into the soil at an angle which could affect the reading.
You should also look for a meter which works in all types of soil as some only work when they are in moist soil. This means you may have to water the soil and then wait some hours for it to be absorbed before taking a reading which can be time consuming.
The length of time it takes to get a reading is also worth considering. Some meters need longer than other to measure the pH level and if you’re going to be testing frequently this can be frustrating.
Other features to look for is a cleaning pad and a full instruction manual. There is also a benefit to having a warranty as these items are put into outdoor conditions and are exposed to all weathers.
Best pH meter reviews
1. Kelway PHD Soil PH meter (Editor's Choice)
- Includes full instructions
- Used by professional gardeners and nurseries
- Easy to use – just insert into the soil and wait for reading
This professional tool is on most gardener’s wish lists. Although it comes in at a higher price, the accuracy means it is used by nurseries and professional gardeners.
We don't like
- Three in one design
- Small, compact design
- Clear analogue display
This compact meter can be used to measure light, moisture and pH levels around your plant. It can be used in potted plants or placed directly into flowerbeds.
We don't like
- 30-day money back guarantee and 12 month warranty
- Clear and easy to read LCD digital display which has LED for night visability
- Auto power off function
This snazzy-looking piece of gardening kit does four things at once. It can measure moisture levels, pH, and temperature and sunlight intensity. The 200mm probe can be placed in pots, flowerbeds or window boxes.
We don't like
- Operates in temperatures between 5 and 50 degrees C
- Moisture range of 10% to 80%
- Can switch between pH and moisture readings
The XLUX pH meter tester can be used in pot plants, soil and even your lawn. This easy to use meter just plugs straight into the ground you want to test and then you are given a reading after 10 minutes.
We don't like
- Large, easy to read dial
- Cleaning pad included so you can clean off the testing prongs
- Gives you measurements for nitrogen, phosphorous and potash levels
This four way tester measures pH as well as moisture, sunlight and how fertile the soil is. You can use it anywhere and has an instruction manual included in the pack.
We don't like
So after looking at all of these products in detail the clear winner has to be the Kelway PHD Soil PH meter. This product doesn’t need a power source so you won’t have to worry about it not working at a critical time and it comes with full instructions.
It is a compact size and has a short sensor, unlike some of the other models, which means you can tuck it right under even the thickest of garden plants.
While it doesn’t test sunlight or moisture like the other meters, by focusing on one operation it gives a more accurate reading.