START WITH YOUR SOIL · 7 MIN READ
How to test
your soil’s pH
Before you add something to your soil, find out what it needs. A careful sample is the first step toward a useful result.
Start with the sample ↓
01 / THE BASICS
What does soil pH tell you?
pH describes how acidic or alkaline your soil is. Below 7 is acidic, 7 is neutral, and above 7 is alkaline. It affects how available nutrients are to plants.
A pH around 6.5 suits many garden plants. But there is no single target for everything: blueberries and other acid-loving plants have different needs. RHS: understanding soil pH.
02 / PICK YOUR APPROACH
Which test should you use?
A soil testing lab
Choose this when planning a new garden, investigating a persistent problem, or deciding how much amendment to apply. Ask for pH and recommendations for your intended plants.
A home colour kit
A practical first check. Use a kit intended for soil, with its own reagent and colour chart. Follow its quantities and reading time carefully.
A suitable pH meter
Useful for repeated measurements, provided it is calibrated and used correctly. Check whether your model tests prepared soil mixtures or is designed for direct soil insertion.
Method guidance: UMN Soil Testing Laboratory and Hanna Instruments: soil pH testing.
03 / A GOOD SAMPLE
Collect soil that represents the whole area.
One scoop from one corner may miss what is happening elsewhere. Test different beds, lawns and problem patches separately.
Gather these first
- A clean trowel or soil sampler
- A clean plastic bucket
- A labelled bag or container
- Your kit or laboratory’s sampling instructions
Choose one consistent area.
Keep places with different soil, planting history or treatments in separate samples. Label each area before you start.
Clear the surface.
Move loose leaves and mulch aside. Collect soil from the depth specified by your laboratory for the type of planting.
Take several equal portions.
For example, UMN recommends 4–6 subsamples for a garden. Take them from different spots at a consistent depth. Your chosen lab’s instructions take priority.
Combine and label.
Mix the portions thoroughly in the clean bucket. Take the required amount from that mixture. Follow the lab’s drying, packaging and submission directions.
Sampling reference: UMN: step-by-step soil sampling.
04 / AT-HOME TESTING
Let your test’s instructions set the recipe.
There is no universal soil-to-water ratio for every test. Changing the preparation method can change the result. Use the quantities, water or preparation solution, and waiting time specified for your equipment.
Using a colour kit
- Measure the prepared soil into the test container.
- Add the specified water and reagent.
- Mix and wait for the stated time.
- Compare with the supplied chart in good light. Record the closest reading without inventing extra decimal places.
Using a meter
- Calibrate with the buffers specified in its manual.
- Prepare the sample using the manufacturer’s soil-testing procedure.
- Position the probe as directed and wait for a stable reading.
- Record the value, then clean and store the probe as instructed.
Do not push a water-testing glass electrode into soil unless it is designed for that use. A direct-soil probe and a meter used in a prepared mixture may need different procedures. Hanna: testing methods; example direct-soil meter manual.
05 / WHAT NEXT?
A result is a starting point—not a shopping list.
Within your plant’s range?
You may not need to adjust pH. Check other growing conditions if the plant is struggling.
Lower than the target?
Lime can raise soil pH. Get a soil-test recommendation before choosing a type or amount.
Higher than the target?
Lowering pH can be difficult in some soils. Seek advice about whether changing the soil or choosing a better-suited plant is practical.
Confirm an unexpected home result before treating an entire bed. Amendment decisions depend on the soil and the plant—not just the number on the display. RHS: interpreting soil pH.
A few common questions
Can I use this guide for coco coir or potting mix?
The sampling principles help, but soil-less growing media need an appropriate testing method. Ask the laboratory or meter manufacturer for instructions for that specific medium.
Does testing my watering water tell me the soil pH?
No. Label the two measurements separately. A water reading is not a measurement of the soil around your roots.
Should I test before adding lime?
Yes. A laboratory recommendation gives you a better basis for choosing the amount than a pH reading alone.
Keep the result. Build from there.
Save your test report with the name of the bed and what you plan to grow. If you need help understanding the next step, share that information with us.
Ask us a growing questionBack to Growing Tips →Written by LinxGrow using the linked horticultural and equipment references. Reviewed September 9, 2026. Photography: Pexels. Sampling and pH illustrations: LinxGrow.