Calculators for home mushroom cultivation
Substrate recipes, spawn ratios, fruiting chamber climate, Martha tent sizing. Everything a monotub grower or small-batch cultivator needs to stop guessing and start producing — calibrated for common cultivated species, free forever.
Every stage, every tool that helps
Mushroom cultivation breaks cleanly into five stages. Each stage has its own set of decisions — these tools handle the math behind each one.
1. Substrate Prep
Pick your recipe, calculate ingredient amounts, hydrate grain to field capacity, and sterilize at the right time and pressure.
- → Mushroom Substrate Calculator — recipe + container + spawn ratio
- → Grain Hydration Calculator — field capacity for rye, WBS, oat, millet
- → Sterilization Time & Pressure Calculator — PSI, duration, step-by-step
2. Spawn & Culture Work
Determine how much grain spawn you need, make liquid culture and agar, and sterilize everything before inoculation.
- → Grain Spawn Calculator — spawn-to-substrate ratios
- → Liquid Culture & Agar Recipe Calculator — honey LC, DME LC, MEA, PDA
- → Sterilization Calculator — LC jars, agar, grain bags
3. Colonization
Incubation in the dark at species-appropriate temperature. No FAE needed — CO₂ helps during colonization. Cross-crop tools apply here.
- → VPD Calculator — set species selector to mushroom
- → Substrate Calculator — includes colonization time estimates
4. Fruiting
Fruiting chamber sizing, fresh air exchange schedule, humidity management. The stage most home growers underprepare for — three dedicated tools now cover it fully.
- → Fruiting Chamber Calculator — SGFC, Martha tent, monotub sizing
- → FAE Fan Timing Calculator — fan on-time, ACH, timer settings
- → Fruiting Humidifier Sizer — mL/hr output for 85–95% RH
- → VPD Calculator — fruiting targets 0.5–1.0 kPa
5. Harvest & Post-Harvest
Flush timing, drying schedules, and storage. Multi-flush harvests from a single tub require timing decisions most first-time growers don't anticipate.
- Flush Timing Calculator — in development
- Drying Weight Estimator — in development
- Storage Planner — in development
The full list
Also useful for mushrooms
Mushroom cultivator questions
Which tool does a first-time mushroom grower need most?
The Substrate Calculator. Most first-grow failures trace back to substrate prep: wrong hydration, wrong spawn ratio, wrong container volume for the recipe. Nail those three and colonization usually takes care of itself. The calculator takes your container, recipe, and ratio and gives you exact weights, volumes, and prep instructions so there's nothing left to guess.
What species do these tools support?
The tools are calibrated for common cultivated culinary and functional species — oyster varieties (pearl, blue, pink, yellow, king), shiitake, lion's mane, reishi, turkey tail, maitake, and pioppino. Coprophilous species (those requiring manure-based substrates) and exotic species with unusual requirements fall outside the defaults. The Substrate Calculator's recipe selector covers the most common substrate needs across these species. If you're growing something unusual, Grōbot can guide you on where the defaults apply and where to adjust.
Why does VPD matter for mushrooms? Isn't it a plant thing?
VPD matters anywhere water evaporation affects an organism. For mushrooms, it's the difference between pinning, fruiting, and drying out. Fruiting bodies want low VPD (roughly 0.5–1.0 kPa depending on species) because higher VPD pulls moisture from caps and stems faster than the substrate can replenish. Use the VPD Calculator with the mushroom crop setting — stage targets differ significantly from the cannabis defaults.
Can I use these tools for monotub grows specifically?
Yes — the Substrate Calculator has explicit support for common monotub sizes (6qt shoebox, 32qt, 54qt, 66qt). It calculates substrate depth, total volume, spawn ratio, and shopping list for the exact container you're using. VPD still applies when you transition to fruiting, though most monotub growers don't run active fruiting chambers; the substrate itself and tub humidity usually dominate.
Are these tools OK for commercial or semi-commercial scale?
The math works at any scale, but the defaults assume home cultivation — monotub to Martha tent size. At commercial scale (dedicated fruiting rooms, multiple tubs per batch, continuous production), the tools are a starting point for recipe and ratio work, but you'll want to layer on HVAC sizing, automation, and contamination control that go beyond what the calculators cover. The Fruiting Chamber Calculator (in development) will include more scale-sensitive options.
What's the difference between pasteurization and sterilization, and how does that affect the calculator?
Pasteurization kills most competitor organisms but leaves beneficial bacteria alive, which gives your spawn a competitive edge on bulk substrates (CVG, straw, manure). Sterilization kills everything, required for nutrient-rich substrates like Master's Mix that contamination would otherwise dominate. The Substrate Calculator's recipe selector knows which prep method each recipe requires and tells you the temperature and time in the output — pasteurize 165°F for 1 hour for CVG, sterilize at 15 psi for 2.5 hours for Master's Mix, and so on.