FoxFarm Ocean Forest Soil Review: Lab Results

Last updated: November 2, 2026

Quick answer: I sent a cup of FoxFarm Ocean Forest to the University of Delaware for a greenhouse-media lab test. My home slurry measured pH 6.26 and 400 PPM. The lab’s saturated-media extract measured pH 5.9 and soluble salts of 1.42 mmhos/cm (the same numeric unit as mS/cm).

My Ocean Forest comparison. English captions are available from the CC menu.

Video chapters: Ocean Forest home test vs. lab test

0:00 — Why send the soil to a lab?
0:10 — Home slurry: pH 6.26 and 400 PPM
0:28 — University lab report
0:30 — Lab pH: 5.9
0:44 — Bag analysis versus extract data
1:19 — Nitrate and calcium discussion
1:34 — Remaining nutrient results
1:49 — My amendment advice
2:02 — Fungus-gnat experience

Selecting a timestamp opens the video at that moment without moving you away from this section.

What I tested

The sample went through the University of Delaware’s GH-1 SME Media Analysis. SME means saturated media extract. The package measures pH, electrical conductivity and extractable P, K, Ca, Mg, Mn, Zn, Cu, Fe, B, S, Na, Al, nitrate-N and ammonium-N. That is the right kind of service for a container medium.

The University describes this as a greenhouse-media analysis, and its current program still lists the same core measurements. See the University of Delaware soil-testing program and GH-1 package.

University of Delaware saturated media extract report showing FoxFarm Ocean Forest pH 5.9 and soluble salts 1.42 — My sample measured pH 5.9 and soluble salts of 1.42 mmhos/cm.

Ocean Forest lab results

pH	5.9 — lab interpretation: optimum
Soluble salts / EC	1.42 mmhos/cm — lab note: low fertility unless applied with every watering; suitable for seedlings, newly rooted cuttings and salt-sensitive plants
Nitrate-N	0.6 ppm — low
Phosphorus	5.1 ppm — acceptable
Potassium	101.9 ppm — acceptable
Calcium	91.9 ppm — acceptable
Magnesium	71.1 ppm — optimum
Manganese	0.02 ppm — low
Zinc	0.06 ppm — low
Copper	0.10 ppm — low
Iron	0.12 ppm — low
Sodium	32.70 ppm — high
Boron	0.11 ppm — optimum
Sulfur	194.1 ppm — high
Aluminum	0.27 ppm — not rated

Low, acceptable, optimum and high are the lab’s own interpretation ranges. They are not a cannabis-specific recipe, so I would not pour anything into a planted pot based on them alone.

FoxFarm Ocean Forest saturated media extract nutrient results for nitrate phosphorus potassium calcium magnesium and trace elements — The saturated-media extract reports soluble or extractable concentrations in ppm. It is not the same thing as the guaranteed-analysis percentages printed on the bag.

Why the home and lab numbers differ

I got pH 6.26 at home and the lab got 5.9. A slurry result changes with the soil-to-water ratio, water chemistry, contact time, temperature, meter calibration, filtering and sampling. The lab used a standardized saturated-media extract. A home test is a helpful trend check when you repeat the same method every time.

The same goes for my 400 PPM. Consumer meters convert EC to PPM with a 500, 640 or 700 scale, and I did not name mine in the video. The lab’s 1.42 mmhos/cm came from a different preparation, so I do not compare those two numbers. Use the repeatable soil slurry method for home trending and the pH, EC, PPM and runoff guide to keep the units straight.

Do not compare the bag’s NPK directly with this table

In the video I read the bag analysis as 3-4.5-0.5, but I moved the decimal. The label reads 0.30-0.45-0.05. Those percentages are nutrient content by weight, and the lab table reports concentrations in the saturated extract.

The low nitrate result means little nitrate-N was in that extract at that moment. Organic nitrogen can mineralize over time through the wider microbial community.

Does Ocean Forest need fertilizer right away?

Not automatically. FoxFarm’s current Ocean Forest page calls the mix ready to use and specifically says there is no need for nitrogen fertilizer at first. It suggests feeding later during growth and bloom. The manufacturer currently lists aged forest products, sphagnum peat moss, earthworm castings, bat guano, fish emulsion and crab meal in the blend. Check the current Ocean Forest ingredients and directions.

I used to call Grow Big a “perfect complement,” start around 150 PPM, add calcium and use four tablespoons of Bio-Fish per five-gallon pot. These days I let the plant and the numbers decide. Calcium was acceptable in this report, and adding any fertilizer changes more than one nutrient at a time.

If an established plant, your source water and repeatable root-zone measurements point to a real need, choose a complete program and measure the final mixture. The FoxFarm Grow Big pH and EC test shows what that bottle did in my water sample; the nutrient-deficiency guide helps separate symptoms before you add more.

Ocean Forest workflow

Record the bag and lot. Soil products vary. Photograph the label and keep the lot code before opening.
Inspect before planting. Look for odor, pests and uneven moisture. I have had repeated fungus-gnat problems from past bags, so check every one.
Use it as a starting medium. Plant, water thoroughly and allow the root zone to establish before assuming the fresh soil needs a corrective fertilizer.
Trend with one method. If you run a home slurry, keep the ratio, water, timing, temperature and your calibrated pH and EC meter consistent.
Read your local water report. Search your ZIP code plus “water report”. Alkalinity and dissolved minerals can change the behavior of both pH and supplements.
Diagnose before amending. Combine plant symptoms with input EC/pH, runoff or slurry trends, water data and stage. Do not chase one number.
Change one variable at a time. Follow the current product label, start conservatively and measure the response before adding a second correction.

Recommended Ocean Forest testing and amendment supplies

FoxFarm Ocean Forest Potting Soil with 2 Plant Tags, 1.5 cu ft – Light, Aerated Texture – for All Container Plants

FoxFarm Ocean Forest soilThe exact product tested. Compare the online price with a local garden store because shipping soil can be expensive.View product

Digital pH Tester for Water, pH Meter for Hydroponic Water

pH and EC meter kitFor repeatable slurry, source-water and feed checks. Calibrate the probes and record the PPM scale when EC is unavailable.View product

Mosquito BitsA Bti-based option for fungus-gnat larvae when the current label permits the intended use. Follow the label rather than applying it automatically.View product

Calcium-magnesium supplementThe legacy calcium link, retained as an option only when water, medium and plant evidence identifies a real calcium or magnesium need.View product

Down To Earth All Natural Fertilizers Organic Bio-Fish - 7-7-2, 25 lb

Bio-Fish 7-7-2 fertilizerThe legacy organic amendment link. Do not copy the old blanket dose; follow the current label and adjust only from measured need.View product

Affiliate disclosure: HWGrow may earn a commission from qualifying purchases at no additional cost to you. Product destinations may be replaced with equivalent items; verify the exact product, current label and fit for your grow before use.

Next in your grow

Before this step: How to Light Cannabis and Choosing LED Grow Lights

Next step: Best Way to Germinate Cannabis Seeds: 7 Methods Tested

Go deeper (supporter membership required): These advanced guides are for HWGrow supporters: HWG’s Organic Super Soil – 7 Ingredients with Amazing Results – Optimized Recipe · How to Recycle Soil Organically: Re-Amend Used Potting Soil. Become a supporter.

Want help reading your own soil data?

The Grow With Me Masterclass connects water, feeding and root-zone measurements inside a guided workflow without reproducing protected lesson content here. If your numbers or symptoms do not match this sample, ask HWGrow a question and include the soil brand and lot, plant stage, water report, meter calibration, exact test method, pH, EC or named PPM scale and clear plant photos.

FoxFarm Ocean Forest FAQ

What pH did Ocean Forest test at?

My home slurry measured pH 6.26, and the University of Delaware saturated-media extract measured pH 5.9. Different preparation methods can give different results.

What EC did the lab report?

The report listed soluble salts of 1.42 mmhos/cm, numerically equivalent to 1.42 mS/cm. I do not compare that directly with my 400-PPM home reading.

Does fresh Ocean Forest need Grow Big or Cal-Mag?

Not automatically. FoxFarm currently describes Ocean Forest as ready to use and says no nitrogen fertilizer is needed at first. My lab sample rated calcium acceptable. Add nutrients when the plant, water and root-zone numbers call for it.

Why does the bag analysis not match the lab ppm?

The bag’s 0.30-0.45-0.05 guaranteed analysis is nutrient content by weight. The laboratory ppm values are concentrations in a saturated-media extract. They are different measurements.

Does Ocean Forest always contain fungus gnats?

I cannot speak for every bag, but I have had repeated fungus-gnat problems. Inspect each bag, quarantine when practical and use label-directed integrated pest management if pests are present.