Soil testing
A laboratory result, not a guess.
Post a sample to an independent laboratory and the report comes back into your garden, zone by zone, in plain English — with how much to add and why.
Soil testing
£39.99 / £49.99 inc VAT
LOAM £39.99 · LOAM Plus £49.99 · one box covers up to six zones
Kit posted to UK addresses · full refund until your sample reaches the lab · UK only for now
What the lab measures
Five figures, plainly explained.
The laboratory measures soil pH, the phosphorus, potassium and magnesium levels, and organic matter as a percentage. That is the whole of it.
- pHLOAM
- Acidity or alkalinity, on the 1–14 scale. It decides what roots can take up, and it is the figure lime or sulphur moves. This is the one a gardener changes on purpose.
- PhosphorusLOAM
- Reported as a figure in mg/l and as an index. Roots, flowers and fruit set depend on it — and it is easy to overdo, which is why the advice can be to add nothing.
- PotassiumLOAM
- mg/l and an index. It carries fruit quality and how well a plant stands up to cold and drought.
- MagnesiumLOAM
- Plant-available magnesium, in mg/l and as an index. Leaf colour, and how well a plant turns sunlight into growth.
- Organic matterLOAM Plus
- A percentage. The part of the soil that holds water, feeds soil life and buffers everything else. Only LOAM Plus has it — it is the one figure the upper tier adds.
How the analysis is done
The laboratory uses Olsen's phosphorus with UK Soils Methods. Phosphorus, potassium and magnesium are reported both in mg/l and as an index, and the index is derived from the mg/l figures alone, to the published standard — it takes no account of crop or field. Results are interpreted against published index systems, and where our advice departs from published guidance we say so on the advice itself, and say why.
Posting a sample
Five steps, and nothing physical passes through us.
The kit comes from the laboratory, the sample goes back to the laboratory, and we receive the report and put it in your app.
01
The laboratory posts your box
One sample bag for each zone you chose, up to six zones per box. The box comes with instructions and a prepaid envelope for sending your samples in.
02
Take three small samples per zone
For each zone, take a handful of soil from each of three evenly spaced spots, about 2–3 cm down (an inch or so), and mix them together in that zone's bag. Three spots describe the zone; one hole only describes the hole.
03
Write the plot reference on the bag
Each zone has its own reference number. The app generates it, the bags carry it, and the laboratory reports against it — not against your name.
04
Post the box back
In the prepaid envelope, straight to the laboratory. The analysis is carried out by an independent laboratory; we arrange it and interpret the results.
05
We check, then release the result
Every result is checked before it reaches you — a reading outside the plausible range, a blank pH, a plot reference matching no zone, or the laboratory's index contradicting its own figure each hold the result back.
Changing your mind
You can cancel and get all your money back at any time until your soil reaches the laboratory: cancel yourself in your account before your kit is posted, or email hello@growproltd.com after that and we will do it for you. A kit already posted is yours to keep — there is nothing to send back and nothing to pay for it. Once your soil reaches the laboratory we cannot refund you, because they charge us the full price for the analysis whether you want the report or not.
The two tiers
LOAM or LOAM Plus.
Both tiers measure the same four figures. LOAM Plus adds organic matter. One box covers up to six zones either way, whatever the tier.
| What is measured | LOAM£39.99 inc VAT | LOAM Plus£49.99 inc VAT |
|---|---|---|
| Soil pH | Included | Included |
| Phosphorus (mg/l and index) | Included | Included |
| Potassium (mg/l and index) | Included | Included |
| Magnesium (mg/l and index) | Included | Included |
| Organic matter (percentage) | — | Included |
| Sample bags per box | Six, one per zone | Six, one per zone |
| Zones per box | Up to six | Up to six |
The laboratory posts the kit directly, so your name and address go to them for that one purpose. Nothing physical passes through us at any point.
The report back
One report, everything explained.
Every figure arrives against the zone it came from, with the laboratory measurement kept separate from our advice.
Every dose floors its rounding, because overdosing lime damages soil. Where the app suggests nothing, the suggestion is nothing.
Zone 3 · Plot reference: GP-4K7P
Illustrative excerpt — not a customer result. The values are examples of the shape of a report, not a measurement of your soil.
- pH
- 6.4Slightly acid — comfortable for most vegetables and for the plan’s plants.
- Phosphorus
- Index 2 · 24 mg/lAdequate. No phosphate feed suggested this season.
- Potassium
- Index 2 · 183 mg/lAdequate. Top up with wood ash only if you crop heavily.
- Magnesium
- Index 3 · 121 mg/lWell supplied. Epsom salts would be wasted here.
- Organic matter
- 4.1%On the low side — compost is the place to spend effort.
What we would suggest
Nothing to add before spring. Keep the soil mulched over winter and add compost in February; the pH needs no lime this year.
After the results
The figures are yours. The advice is ours.
We show you what the laboratory measured and what we think you should do about it. The measurements are simply facts about your soil.
- The result lands in that zone’s soil panel in your garden, so the dose and the zone stay together.
- Soil texture and free chalk are not laboratory tests. You tell us those with the hand test and the vinegar test in the app, and we combine them with what the laboratory sends back — always saying which figure came from where.
- If a sample arrives damaged or cannot be analysed, the laboratory sends a replacement kit and asks for another sample. There is no charge to you.
- Most reports reach you within two weeks of the day you post your sample back. Four weeks from that day is the agreed period: if it has not arrived, tell us and we will give you a date — and if we miss that date too, you can end the contract and get a full refund.
The clock starts when you post
The time a kit waits on your hallway table is yours and does not count. The four weeks run from the day your sample goes back in the post.
What the test does not cover
Contamination such as lead, arsenic or cadmium is a separate screen you would have to order specifically. Soil-borne pests and diseases, and composts, manures or container growing media, are not covered either. If you think your site may be contaminated, because of what was there before or what is next door, say so before you order and we will tell you what to ask for.
Soil testing FAQs
The questions we get before an order.
What does the soil test include?
The laboratory measures soil pH, phosphorus, potassium and magnesium — reported in mg/l and as an index — and, in LOAM Plus, organic matter as a percentage. Both tiers cover up to six zones per box, with one sample bag per zone. LOAM is £39.99 and LOAM Plus is £49.99.
How do I take the sample?
For each zone, take a handful of soil from each of three evenly spaced spots, about 2–3 cm down (an inch or so), and mix them together in that zone’s bag. Three spots describe the zone; one hole only describes the hole. One box covers up to six zones, with one sample bag per zone, and comes with a prepaid envelope for sending it back.
When do the results come back?
Most reports reach you within two weeks of the day you post your sample back to the laboratory. Four weeks from that day is the period we agree with you: if your report has not arrived by then, tell us and we will give you a date — and if we miss that date too, you can end the contract and get a full refund. The time a kit waits on your table does not count.
Can I cancel a soil test?
Yes — and get all of your money back, any time until your soil reaches the laboratory. Cancel from your account before the kit is posted, or email hello@growproltd.com after that. A kit already posted is yours to keep: there is nothing to send back and nothing to pay for it.
Can I order a soil test in Germany?
Not yet. The soil test is a UK service for now, because the laboratory is a UK laboratory. German gardeners can use everything else.
Test the soil when you are ready.
Everything in the app is free. The soil test is the one thing you pay for, and it goes to a real laboratory.