Library · Substrate & soil

Substrate Lifecycle.

By · Free, in your browser

What this is
Calculator
Domain
Substrate & soil
Cost
Free — no account
Use
In the browser, or embed

Substrate Lifecycle Calculator

Cost-over-time comparison of single-use vs reusable substrates. The economic case for living soil, the practical case for rockwool.

Compare across N cycles

~6-8 cycles per year for cannabis; 24+ for lettuce

Per-pot costs (one-time setup)

Per slab; single-use typical
Per 5-gal pot; 2-4 reuses possible
15-25 gal pot; high upfront, indefinite reuse
Per 5-gal pot; single-use typical

Reuse cycles per substrate

Typically indefinite with top-dressing

Per-cycle ongoing costs

Compost, amendments, kelp etc.

Total cost over — cycles

When each substrate wins

SubstrateWins for
Rockwool single-useCommercial precision growers; predictable EC/pH; easy disposal mid-cycle if needed
Coco coirMid-budget hydroponic-like; good drainage; OMRI options
Living soil (no-till)Long-term operations; quality-focused growers; regenerative; lowest per-cycle cost after year 2
ProMix / engineered blendsBeginners; one-off cycles; transplant-friendly
Hydroton (clay pebbles)Recirculating hydroponic; many reuses; ebb-flow systems
Outdoor field soilField-scale; lowest cost; substrate cost effectively zero

Hidden costs to remember

  • Disposal — rockwool isn't biodegradable; some jurisdictions restrict landfilling. Coco/peat compost. Living soil never leaves the bed.
  • Sterilization labor — reusing rockwool requires steam-sterilization; significant labor cost for small operations
  • Pest carryover — reused substrate can carry pests/disease; cleanup process matters
  • Water cost differences — hydroponic substrates use less water than soil; living soil holds water longest
  • Setup labor — living soil requires significant initial mixing labor; rockwool just opens a pre-cut slab
  • Storage — reusable substrates need storage between cycles; single-use means no storage need

Break-even analysis (cannabis 5-gal context, typical numbers)

For 20× 5-gal pots, $0.13/kWh, 56-day flower cycles:

  • Cycle 1: Rockwool $240; Coco $120; ProMix $200; Living soil $1,600 + topdress $160 = $1,760
  • Cycles 1-6 (6 cycles): Rockwool $1,440; Coco $480; ProMix $1,200; Living soil $1,600 + 6× $160 = $2,560
  • Cycles 1-12 (~2 years): Rockwool $2,880; Coco $1,440; ProMix $2,400; Living soil $1,600 + 12× $160 = $3,520 (still $2,560 if 12 reuses fit)
  • Living soil break-even vs rockwool: roughly cycle 8-10. After that, living soil saves money cumulatively.
  • Living soil break-even vs coco: never per pure substrate cost — but living soil quality + biology benefits aren't priced into substrate alone.

Related widgets

Free under CC BY 4.0. Cite as "OAT Substrate Lifecycle Calculator (openagriculturetechnology.com)".