How to Test Your Soil For PH
Putting soil testing kits… to the test
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Have you ever wondered why plants grown at nurseries and garden centres produce an abundance of flowers yet, once planted in your garden, they fade and rarely thrive?
Every plant, whether it’s a bedding plant, a shrub or a climber, will grow optimally if planted in soil within a specific pH range and with sufficient nutrient content.
Sure, your plants may survive if grown in less optimal soil conditions, but to truly thrive, you’ll need to follow these simple steps:
- Research the plant online and note the ideal soil conditions for it.
- Test your soil with a pH testing kit, powder nutrient kit or off-site service.
- Mix additives/fertilisers to your soil to change the pH level and nutrient content.
- Consider relocating plants when the soil can’t be amended.
On this page we’ll look at your four options:
- pH test strips.
- Soil nutrient kits.
- Off-site analysis.
- Electronic soil testers
1) Garden Tutor’s Soil Testing Strips
I tested these pH soil testing strips in June 2022, and they are very similar to products sold by competitors:
Watch my short video review here:
The box I purchased contained:
- 100 test strips.
- A booklet with instructions.
- A colour chart for determining the results.
I found that using the test strips couldn’t be easier:
- I mixed water and soil in a clean cup.
- Left the mixture for a few hours.
- I then dipped the test strip into the mixture.
- The three squares at the tip of the strip changed colour.
- I then compared the results to the colour chart with gave an approximate reading.
What I Like and Dislikes About These Test Strips
Likes: They are cheap and easy to use; I also got the results quickly. The booklet advises one to wait 8 hours before dipping the test strip into the mixture but also claims you will get accurate results after just one hour. I also liked the number of strips in the bottle – 100, which is plenty.
Dislikes: I found it somewhat difficult to compare the three coloured squares to the colour chart. The booklet stated that I should find the “closest match” but while I could easily see the results for each individual square, I couldn’t find a corresponding match for all three together. I had to calculate an average number from all three which is a little bit of hassle and not 100% accurate.
2) Luster Leaf Soil Test
Luster Leaf produces several soil testing kits, from single pH tests to more complete systems.
These test kits I purchased when I lived at my previous property and I used them to check the pH, Nitrogen, Phosphorous and Potash levels. If you’ve ever purchased fertiliser, you’ll know that these are represented by letters (NPK) and numbers on the product label.
The results from the Luster Leaf test kits helped me as I could then adjust the fertiliser I used in my garden.
In the pack, I found four plastic square boxes with colour charts printed on the front of the pack.
Getting results was easy and quick, I just mixed the soil and water together and poured them into each square box.
Next, I added the powder from the capsule and shook the box until the powder dissolved.
After a short while, the water changed colour, and I could compare this to the colour chart.
There are ten capsules per box (double check you’ve purchased product #1601 as cheaper products have fewer capsules), so I could conduct ten tests per box, 40 in total.
What I Like and Dislike About This Test Kit
Likes: I was able to test for Nitrogen, Phosphorous and Potash in addition to the pH, so the results really helped me decide which fertiliser I should use, rather than just buying a general one and guessing what the plants need. I like the boxes, which made it easier to carry out the tests, and this kit feels more professional than the standard litmus test strips.
Dislikes: I would prefer more capsules as it only came with ten for each test, and I split one by mistake. I feel the kit is expensive and costs nearly as much as a single lab analysis test.
Note: Pack #1601 contains 4 x 10 capsules, while pack #1602 is cheaper but only contains 4 x 5 capsules.
3) Off-Site Soil Analysis
If you don’t want to test the soil yourself, you can send off soil samples to a laboratory, and you’ll get a detailed report within a couple of weeks.
I’ve used the Royal Horticultural Society’s soil analysis service in the past, and I highly recommend them.
I sent off a sample a few years ago, and they tested it for pH level, organic matter and amounts of Nitrogen, Potash and Phosphorous. Also, the report they sent back contains suggestions for improving the soil for vegetables, fruits, lawns and ornamental plants.
I just checked their website and they currently charge £40 per sample with a discount to £33 for members.
Waiting times vary throughout the year, but I’ve seen them report delays of up to three weeks to get the results during the busy spring and early summer months.
4) Electronic Soil Testers
There are two types of electronic soil tester worth considering; moisture testers and all-in-one testers.
I used moisture testers years ago, and I always found them to be very reliable and handy if you are worried about watering sensitive plants too much or too little.
My experience with all-in-one testers has been mixed; they work well at detecting light and moisture but when I compared them to chemical testers, I found they weren’t that accurate.
My advice: I suggest you use powder kits and litmus strip testers for determining pH, N, P and K levels and only use electronic testers for moisture and light levels in the soil.
3-1 Soil Tester
This tester will reveal the light and moisture levels in the soil accurately. I’ve used this device to gauge how much water I should use on plants or to test the ground soil – some plants thrive in wet, boggy soil while others hate it.
The manufacturers also claim that this testing device will reveal the soil’s pH levels but I found the results to be vague and inconsistent.
Before you place new plants in your garden, use this device to test the soil for moisture content. Some gardens naturally drain well while others hold more moisture, this isn’t always obvious at ground level.
With the results, you can choose the appropriate plants for your soil or add organic matter and fertilisers to change your soil’s makeup. I’ve found testers like this to be very accurate.
I Analysed Hundreds of Online Reviews: This Is What I Found
While I’ve used soil testing strips, powder kits and the RHS’s service before, I decided to analyse as many online reviews as I could find.
This is what I found:
RHS Testing Service: Reviews for the RHS testing service are hard to come by, but my experience was outstanding; the results were easy to read, and the advice helpful. My only complaint is the time it took to get the results back; 3 weeks is a long time to wait.
Powder Test Kits: Most negative reviews for the powder chemical testing kits were focused on the amount of chemicals in each vial/capsule. Many of the reviewers stated that the products worked well and they were pleased with the results, but there wasn’t enough powder to repeat the tests as many times as they would like.
Litmus pH Test Strips: Reviews of the litmus test strips were mixed with quite a few stating that they couldn’t get an accurate reading by comparing the three squares to the colour chart.
Moisture Meter: There were very few negative reviews for the electronic moisture meter, and I know from experience that these devices and the light detectors are generally accurate.
Electronic pH Meter: The electronic pH meter is a different matter altogether, reviews were generally very poor, and many claimed that the pH reader was inaccurate or broken. If you’re buying this product solely for the pH reader, then I think you might be disappointed.
Based on my experience with soil testing strips, kits and off-site analysis I believe the powder test kits offer the best value for money as you can repeat the tests several times and while they cost more than the somewhat basic pH strip tests, they are cheaper than off-site analysis which only gives you results for one test.
The pH test strips provide the user with a guideline range to the soil’s pH but beyond that, I didn’t find them helpful beyond that.
The off-site analysis could be beneficial to anyone who wants to invest thousands of pounds in new trees, shrubs and plants for their garden but for the average gardener, it’s probably overkill, and you’ll have to wait for the results.
(Postscript: I’ve since published a more in-depth review of the pH strips here)
What is the Best pH Level For Garden Soil?
Most plants thrive in soil with a pH level of between 6 and 7, that’s slightly on the acidic side of neutral.
Some plants will prefer slightly more alkaline or more acidic soil.
For example; many heathers prefer soil around 5pH while mint, ginger and thyme thrive in soil with pH of up to 8.
pH is measured on a scale of 1 – 14.
1 is very acidic such as gastric acid.
7 is neutral, ie pure distilled water.
14 is very alkaline, for example; bleach.
Soil Testing FAQs
How Accurate Are Litmus pH Test Strips?
You can use pH testing strips to measure the acidity levels of the soil and I’ve found the results to be adequate. You’ll need to mix the soil with distilled water first to get the most accurate results.
Do Electronic Soil Testing Devices Work?
I’ve found that electronic devices sold online and in garden centres work very well at measuring the moisture and light levels in the soil. However, the readings provided for pH levels are often inconsistent and don’t match the more reliable chemical powder test kits.
What is the Ideal pH Level for Soil?
Plants all require different pH levels so you’ll need to research the needs of the plants you intend to plant in your garden. Most plants thrive in soil that has a pH of between 6 and 7, although some plants prefer more acidic or slightly more alkaline soil.
What Happens if I Grow Plants in Soil That's Too Acidic or Alkaline?
A slightly acidic soil is just right for most plants. However, if the pH level is too high, the plants lose their ability to absorb nutrients. With poor nutrient uptake, leaves and stems may turn yellow, and growth is stunted.
I have witnessed this first-hand as I tried to grow plants under the pine trees in my garden, and they struggled. It was only after I tested the soil, did I realise how acidic the soil was, and I now grow appropriate plants under those pine trees.
Do I Really Need to Know My Soil's Nitrogen, Phosphorus and Potash (NPK) Content?
If you don’t know how much Nitrogen, Phosphorus and Potash (NPK) are in your soil then you can only guess how much fertiliser to use.
Get it wrong and your plants may grow tall and leggy with few blooms or short and stunted.
A soil test kit will provide you with results that allow you to adjust your feed accordingly, rather than just guessing.
Author: Daniel Woodley
Daniel has over 18 years of experience in the construction, home improvement, and landscape garden industries.
He previously worked as a project manager and has experience in managing teams of tradespeople and landscape gardeners on both small and medium sized projects.
Daniel is also a keen gardener and enjoys growing unusual plants and tending to his lawn.
Why Trust Us? Our Experience & Testing
The team here at DIY Gardening carries out thorough testing and analysis of every product we feature on this website.
When we examined soil testing kits, we looked for:
- The price and how much it costs compared to the competition.
- How easy the kit was to use.
- How accurate and easy to understand the results were.
- Reviews and ratings online and any complaints or compliments other buyers had mentioned.
- How useful the product was and whether it was worth the cost and effort.
Daniel Woodley published this review. Claims and important statements were fact-checked by horticulturist Elizabeth Smith prior to publication.
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