Soil pH Pen by Bluelab — Direct-Reading Soil & Media pH Meter
BL-MTR-PHPEN-SOIL
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Pairs well with
The Bluelab Soil pH Pen reads pH and temperature directly in soil, coco, potting mix and other growing media — push the probe into the root zone and read the number, no slurry mixing required. The integrated storage cap doubles as a dibber that makes a safe pathway for the glass probe, and the pen is fully waterproof with automatic temperature compensation. It measures nutrient solutions too, making it the one pH tool a soil grower actually needs.
Specifications
- Always twist the storage cap loose before pulling it off or pushing it on — pulling it straight off breaks the glass probe. Check for the gap between cap and dibber first, every time.
- If it dries, it dies. Keep the probe tip covered in KCl storage solution inside the cap at all times, and check the level monthly in long-term storage. A dried-out probe needs a 24-hour KCl re-soak and may already be permanently damaged.
- Never store, soak or rinse the probe in RO, distilled or deionised water — pure water changes the reference chemistry and kills the probe.
- Clean the glassware monthly and before every calibration with Bluelab pH Probe Cleaner or mild detergent and a soft toothbrush — a dirty probe won't calibrate accurately.
How to Use — First Use Setup
Pairs Well With
pH 7.0 and 4.0 sachets plus KCl storage solution — the pen needs both to stay accurate and hydrated.
Organic GardeningLiving-soil inputs, organic fertilisers and amendments — dial in the root zone the pen is reading.
More From BluelabProbes, monitors and meters from the New Zealand brand growers have relied on for over 30 years.
FAQ
Does it measure soil pH directly, without a slurry?
Yes. The probe reads pH and temperature directly in moist soil, coco and other media — use the cap/dibber to make the pathway first. It can also measure a prepared soil slurry or nutrient solution when you want a bench-style reading.
Can it measure nutrient solutions as well as soil?
Yes. It works in nutrient solutions, reservoirs and soil solutions as well as directly in media, so it covers both the pot and the res.
Do I need to soak the probe before first use?
Yes — check it first. The tip ships stored in KCl solution inside the cap; if the tip isn't covered, top up the KCl and stand the pen upright for 24 hours before calibrating. A dehydrated probe drifts, reads stuck near pH 7 and can be permanently damaged. Never use RO, distilled or deionised water.
Can I use it in dry soil?
No — the sample needs moisture for a reliable reading. For dry samples, Bluelab recommends moistening with RO or distilled water and ideally waiting 24 hours before measuring (tap water shifts the reading with its own pH). Note that's for the soil sample only — never put RO or distilled water on the probe itself.
What pH should my soil be?
Bluelab's recommended range for soil-grown crops is 6.2 – 7.2 pH (plant specific), versus 5.5 – 6.3 for solution growing. Outside the right range, nutrients lock up and plants can't access them no matter how well you feed.
Is the probe replaceable?
No. The Soil pH Pen has a fixed probe — when the glassware ages beyond calibration, the unit is replaced. Good care stretches its life considerably: keep the tip wet in KCl, clean monthly, use the dibber every time and never force the cap.
How often should I calibrate it?
The pen tracks it for you — the calibration check mark disappears 30 days after your last successful calibration. Also recalibrate after every clean, after a battery change, or whenever a reading looks off. Always pH 7.0 first, then 4.0 or 10.0.
Know Your Root Zone.
Soil pH straight from the pot, no slurry required — shipped fast Australia-wide.