Short answer. Living soil is a large volume of compost-rich, amended soil that you reuse without tilling and water with plain, dechlorinated water. Soil microbes and invertebrates mineralise organic matter into plant-available nutrients. Done well, it needs little more than water, mulch and a top-dress between runs. Don't pH-adjust aggressively, don't add salt fertilisers, and don't sanitise it. The evidence base is mostly Grower practice: soil-health principles from agronomy are well established [1], but controlled cannabis comparisons of living soil vs other systems are scarce.
How it works
- Nutrients come from organic amendments (compost, worm castings, seed meals, rock dusts, kelp, bone/fish meal) released by biology. Release speed depends on moisture, temperature and organism activity, so it lags by days to weeks.
- pH is buffered by organic matter and carbonates; plants and microbes work around a near-neutral pH. Jardin leaves living-soil pH uncontrolled at ~6.3–7.0 [4].
- No-till keeps fungal networks and soil structure intact between runs; a mulch layer and optionally a cover crop keep the surface moist and alive (directly echoing NRCS principles: minimise disturbance, keep soil covered, keep living roots, maximise diversity [1]).
Numbers that matter
| Parameter | Target | Notes |
|---|---|---|
| Container volume | ≥ 50–100 L (15–25 US gal) per plant, or beds | Small pots lack buffering; Grower practice |
| Water | Dechlorinated (stand 24 h or carbon filter for chloramine) | pH as-is unless very alkaline |
| Soil moisture | Evenly moist; never dry, never saturated | Jardin uses VWC + soil temperature, dosing disabled [4] |
| Soil temperature | 18–24 °C (64–75 °F) | Biology slows below ~15 °C |
| Mulch | 3–5 cm (1–2 in) straw, leaves or living cover | |
| Top-dress | Between runs and mid-veg; weeks before need | Organic N release is slow |
How to run it
- Build (or buy) a mix of roughly equal parts aeration (pumice/perlite), compost/castings and peat or coco, plus a balanced amendment package. Let it "cook" moist and warm for 2–4 weeks.
- Plant directly; water gently; mulch.
- Water by weight or VWC; living soil wants steady moisture.
- Feed the soil, not the plant: top-dress amendments and water in; compost teas or extracts by hand if you use them.
- Between runs: cut stems at soil level, leave roots, top-dress, re-mulch, replant.
Fixing problems
- Diagnose before amending: in living soil, pH or water problems and cold soil cause most "deficiencies".
- Fast-acting organic inputs (fish hydrolysate, kelp extract, a light foliar) bridge a gap while a top-dress breaks down.
- Pests: fungus gnats love moist mulch; use sticky traps and predatory mites or Bacillus thuringiensis israelensis rather than drying the soil out.
Jardin notes
Jardin medium "Living soil": dosing disabled in software, EC targets hidden; Jardin runs moisture, climate, photos and IPM monitoring. Time-to-harm on pump failure: days. Automation level 3 for water [4].
Common mistakes
- Flushing living soil before harvest. There's nothing to flush, and pre-harvest flushing is a Myth that costs yield and resin. Keep watering normally (see the flush debate).
- Small pots of "living soil" fed like hydro.
- Chlorinated or hydrogen-peroxide water, or sanitisers poured on the bed.
- pH-ing water to 6.0 out of habit.
- Over-amending (hot soil) and burning seedlings.
Evidence
Soil-health principles are Established agronomy [1]. Organic feeding can produce high cannabis yields when N supply is adequate (~389 mg N/L liquid organic feed maximised veg yield in coir-based organic media [2]). Claims specific to living soil (better terpenes, "cleaner" smoke, microbial-driven quality) are Grower practice with no controlled cannabis data we can cite.
