By Danny Woodley. Originally posted in the Gardener’s Corner of the Job Prices website. Updated: 1st May 2022.
Have you ever wondered why plants grown in professionally created gardens appear brighter, healthier and have more flowers on them than the same plants grown in your garden?
There’s a good chance that you’ve been growing plants in soil which they aren’t suited to.
Sure, alkaline-sensitive plants such as Heathers and Rhododendrons can be planted in alkaline soil but their growth will be limited and the plant will never reach its full potential.
Place the same plants in acidic soil and you’ll soon have a carpet of bee-friendly Heather and Rhododendron flowers to be proud of.
Choosing plants that are best suited to your existing soil or making changes to your soil so your plants can thrive will make a huge difference to your garden.
In fact, it’s the most important thing you can do.
Testing Kit Options
Step one of any new gardening project is to check the pH level of the soil so you can make informed choices about the plants you’ll be using, rather than relying on luck.
There are several different testing kits and meters you can choose from.
When making your decision, do consider that getting things right early on in your project will save you money in the long term.
Spend a little extra on a good testing kit/meter and you won’t spend the next few years fighting an uphill battle against plants that hate the soil you’ve planted them in.
Here are your options:
- Disposable chemical soil testing kits for pH levels, Nitrogen, Phosphorous and Potash (the cheapest option but you can use each capsule only once)
- Basic electronic meters to detect the pH levels in the soil (more costly but can be used as many times as you need)
- Meters at the more expensive end of the range can also detect moisture levels, soil temperature and also light levels at different depths, (this can reveal how compact the soil is).
For most gardeners, one of these products will be sufficient. Professional gardeners often use both meters and chemical testing kits.
The Best Soil Testing Kits
My advice is to purchase a single testing kit for pH, Nitrogen, Phosphorous and Potash and one electronic pH meter that you can use periodically to keep an eye on the pH levels.
The two products should be more than enough for the average gardener.
Below are the two products I recommend:
Luster Leaf Rapitest Kit
The Rapitest soil testing kit by Luster Leaf contains 40 tests, 10 each for Nitrogen, Potash, Phosperous and soil pH levels.
The kit is incredibly easy to use – simply mix the soil with water and drop in a capsule, the water’s colour will change and you can compare the results on the colour comparison chart.
The results are accurate, fast and you need no prior experience or training to use this soil testing kit.
Use this kit on day one of your project to get a unique understanding of your garden. Follow up periodically as you introduce plants and compost to ensure your soil content stays optimal.
VDROL 3 in 1 Soil Meter
The VDROL soil meter has three functions; testing soil pH acidity levels, moisture content and light levels.
Use this meter indoors or outside, it’s suitable for flower beds, plant pots, lawns, fruit gardens and more.
Just select one of the three options and insert the probe 2-4 inches into the soil.
Within 10 minutes you’ll have an accurate reading.
The VDROL soil testing meter is perfect for those on a low budget and no batteries are required.
The readings are accurate enough for most budding amateur gardeners.
Other Options
Below are two other testing kits worth considering.
Don’t forget; you can test your soil at any time of the year:
The All-In-One Professional Soiling Testing Kit
This all-in-one professional tester’s kit contains over 350 tests – 87 each of Nitrogen, Phosphorus, Potash and pH acidity.
In addition, the kit also comes with a battery-powered meter for pH testing in soil and water so is perfect for lawns, flower beds and ponds.
The meter has an impressive pH range of 1 – 14 with an accuracy of 0.1pH.
This kit is ideal for professionals or those with large or varied gardens.
Use this professional soil testing kit to get accurate readings of the key nutrients at any time of the year and ensure your plants are grown in ideal ground conditions.
Water Testing Strips
If you use water from a tap on your pot or garden plants, be aware that water with a high acidity level can stunt the growth of plants that are sensitive to acids.
The solution?
Test your water supply with these super cheap pH strips, you’ll quickly see exactly what the pH level of your drinking water is and whether it’s suitable for your sensitive plants.
You can then filter your water as required or consider installing rain barrels to collect rainwater from your roof gutters.
If you truly want to maximise the growth and colour of your plants, water testing is just as important as soil testing.
Professional Lab Testing
If you would rather leave the soil testing to the professionals, then there’s good news for you:
The Royal Horticultural Society offers a soil analysis service for around £35 with discounts for members.
Their detailed report includes a full analysis of your garden soil and fertilizer recommendations.
With this detailed report, you can then make adjustments to your soil so your plants will flourish.
Visit the RHS soil testing page here.
Understanding The Soil Test Results
Whether you choose to test the soil yourself with one of the recommended products or you send a sample to a professional lab, use this table as a guide to the results and your next steps:
| pH Level: | Meaning: | Action: |
|---|---|---|
| pH 3-5 | This soil is extremely acidic for plants. Bacteria will struggle to decay and rot organic material at this pH level | Add gardening lime and organic matter to raise the pH level to above pH 5.0 |
| pH 5-6 | Great for lime hating plants but all other plants may grow at a rate below their potential. | Add small amounts of lime and organic matter and retest the soil. |
| pH 6-7 | This is a slightly acidic soil and is perfect for most plants. pH ranges between 6-7 are commonly found in most UK gardens. | Nothing. |
| pH 7-8+ | This soil contains too much alkaline and although plants may grow, they are unlikely to thrive. | Add Sulphur, Aluminium Sulphate or Sulphate of Iron to increase the soil acidity by lowering the pH level. Most garden centres will stock Sulphate of Iron as either a lawn conditioner or soil acidifier |
How to Change Your Soil pH (In a Nutshell)
Choosing plants that best suit your soil’s pH level is the easiest option but you can alter the soil’s pH by:
1) Adding lime to the soil to increase the pH level by reducing the acidity. Learn more about gardening lime here.
2) Adding Sulphur, Aluminium Sulphate or Sulphate of Iron to increase the soil acidity by lowering the pH level. Most garden centres will stock Sulphate of Iron as either a lawn conditioner or soil acidifier, try this product on sale at Amazon.
FAQs
What is the best pH range for my soil?
The optimal range is between 5.5 and 7.5 but if you can, aim for between 6 and 7 pH for most garden plants.
How reliable are home soil testing kits?
For revealing the soil’s pH level, most home testing kits are very reliable.
What happens if the soil pH is too high or too low?
The soil will lack certain nutrients at each end of the scale, which will negatively affect plant growth. With the sweet spot for most plants being between 6-7 pH – slightly acidic.
The graph below shows which nutrients are found in soils of differing pH levels:
This guide to the best soil testing kits was written by Danny Woodley and was last updated in May 2022.
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