This guide is included with your GrowMaster license.
If you already bought the app, enter the key from your checkout email. If you already unlocked GrowMaster in this browser, you are in.
If you have not bought yet, you do not need this page. You can still try the free app. The guide comes with the paid unlock.
Open a section, follow the steps. Use Simple if you just want to know what to tap. Use Technical if you want the numbers behind it.
The left menu is the whole app. Mission Briefing gives you three steps. Do them in this order.
If a button says PRO, the rest of the app still works. You can grow with Main Deck, Germination Bay, Strain Vault, Training, Harvest Bay, and three free Med Bay scans.
Gear Locker sets tent, light, medium, and feed for the current session. Those four values update the sidebar, Main Deck LED height, Nutrient Lab Cal-Mag / pH mode, Feeding watering card, Med Bay prescriptions, and Cost wattage. They are written to the browser only if Pro is active.
On a phone, tap the menu icon (☰) to open the same sidebar.
License key from the purchase email goes in Activate License. After that, Pro tags turn into check marks and Gear Locker saving unlocks.
If you remember only one thing: autos do not get a second chance to recover. Gentle and early is the whole game.
Pro is a one-time unlock. No subscription. No account. After you buy, enter the key from the email.
Nothing is sent to a server. What actually stays in the browser: the Pro license flag, Med Bay scan count (3 free), and Gear Locker fields if you are Pro. Journal entries, DWC pH/EC logs, and checkboxes are session-only — they vanish on refresh unless you exported the journal.
This is the welcome screen. It tells you who the app is for and the three setup steps. Tap Initialize System or Skip to get into the lab. You can open it again anytime from the menu.
Overlay stored as growmaster_intro_seen. Exact audience line: licensed medical cannabis patients, veterans suffering from PTSD, legal caregivers and legal small tent growers. Disclaimer: educational only; follow local law. Same overlay as first launch.
Your daily home screen. Five cards:
Cycle lengths: 56 / 63 (default, labeled 9 Weeks Standard) / 70 / 77 / 84 days. Projected harvest = start date + that many days. T-minus is whole days from today. Future = T-MINUS N DAYS. Zero = HARVEST DAY (orange). Negative = N DAYS OVERDUE (red).
VPD treats air temperature as leaf temperature (no offset). °C = 5 × (°F − 32) / 9. SVP = 0.6108 × e^(17.27 × °C / (°C + 237.3)). VPD (kPa) = SVP − SVP × (RH / 100). Labels: 0.8–1.2 Optimal, below 0.8 Too Humid, above 1.2 Too Dry. Footer also prints seedlings 0.4–0.8 and flower 1.0–1.5. Those extra ranges are notes only — they do not change the Optimal / Too Humid / Too Dry label.
LED heights from Gear Locker wattage — 250W: seedling 24–30", veg 18–24", bloom 12–18" (2×2 to 2×4). 400W: 30–36 / 24–30 / 18–24 (2×4 to 3×3). 600W: 36–42 / 30–36 / 24–30 (3×3 to 4×4, dimmer for seedlings). 1000W: 42"+ dim to 50% / 36–42 / 30–36 (4×4+, must dim seedlings). Tip: taco leaves = too close; stretchy stems = too far.
Quick-reference timeline on this page is fixed: germ day 1–7, seedling 7–14, veg 14–28, flower 28–70+. Daily checklist boxes do not save.
How to pop the seed without killing the auto.
Paper towel is the long walkthrough. When the taproot is about ¼–½ inch, plant it root-down, ¼ inch deep. Do not pinch the white tip.
Paper towel method card: 90–95% success, check every 12 hours, 24–72 hours typical. The long walkthrough also says check every 12–24 hours. Direct soil card: 80–90% success, ¼–½ inch hole, no later transplant.
Timeline is fixed from the plant date — there is no cycle picker on this screen. Sprout expected at +3 days (text says day 2–5). Seedling through day 14. No nutrients until day 14. Veg / LST window day 14–28. Flower start day 28. Early harvest day 70. Late harvest day 85.
Enter start date and Expected Flower Duration (8–12 weeks). Tap Generate Schedule. You get a week-by-week calendar, flush dates, and a watering card that follows Gear Locker (soil, coco, or hydro).
The flush card on the page says start 10–14 days before harvest. Organic / living soil: no bottled flush — stop amendments about two weeks out and keep the microbes going.
Harvest date = start + selected duration + 14 days. Flush start = harvest − 14 days (so flush begins when the selected duration ends). Overview also prints a watering card from Gear Locker: soil every 3–5 days, coco daily, hydro constant / change every 7–10 days, plus “half-strength for autos.”
Calendar shows up to 12 weeks. Weeks 1–2: seedling, water only. Weeks 3–4: early veg. Week 5: mid veg. Weeks 6–7: late veg. Week 8+: flower, then flush / water only once that week’s date hits flush start. Dose still comes from the bottle / Nutrient Lab — this calendar is timing, not milliliters.
Look at trichomes with a 30× loupe. Pick what you see:
Same page has flush notes plus dry and cure: slow dry 7–14 days at 60°F (15–16°C) / 60% RH, dark, stems snap not bend. Jar 75% full. Burp days 1–3: 3× daily, 10 min. Days 4–7: 2× daily, 5 min. Week 2: once daily. Week 3+: every 2–3 days. Week 4+: store sealed. App says 2–4 weeks minimum, 2+ months for premium.
This is the setup that drives the rest of the lab. Four dropdowns:
The notes box then writes pH, Cal-Mag, watering style, and hydro warnings for that combo. Sidebar at the bottom updates to match.
Coco: pH 5.8 (5.5–6.0), Cal-Mag every feed, water daily or drip, fabric pots OK. Soil: pH 6.5 (6.0–7.0), water when the top inch is dry, organics/microbes. DWC: 5.8 pH, 65–68°F water, air stones, change 7–14 days. Ebb & flow: 5.8 pH, flood 3–4× veg / 4–6× flower, hydroton or coco cubes. Hand / drip / wick / hydro each append a short feeding note. Changing these fields also refreshes Main Deck LED height, Nutrient Lab mode, Feeding watering card, Med Bay medium, and Cost wattage. Tent size is not copied into the Vent Calculator boxes. localStorage write happens only if Pro — Free can set the session, then it snaps back to last saved (or 2×4 / 250W / Coco / Hand) on reload.
Pick brand, stage, and gallons. It prints the mix in milliliters (or teaspoons for Fox Farm) already at half-strength for autos. Do not cut it in half again.
Brands in the app: Botanicare (CNS17 + Cal-Mag + Karma), General Hydroponics Flora Series, Fox Farm trio. Stages: seedling, veg, bloom.
pH targets on the same page: coco / DWC 5.8, soil 6.5, runoff within about 0.2 of input. Cal-Mag is required every feed in coco/DWC; optional in good soil.
Doses scale linearly with gallons. Hydro/coco mode is on when Gear Locker medium is Coco, DWC, or EbbFlow (pH target 5.8). Soil uses pH 6.5 and the lower Cal-Mag column. Do not halve these numbers again — they are already half-strength.
Per 1 gallon — Botanicare (ml): Seedling CNS17 Grow 0, Bloom 0, Karma 1, Cal-Mag 1 hydro / 0.5 soil. Veg Grow 5, Bloom 0, Karma 2, Cal-Mag 3 / 1. Bloom Grow 0, Bloom 6, Karma 2, Cal-Mag 3 / 1.
Per 1 gallon — General Hydroponics (ml): Seedling Micro 0.5, Gro 0.5, Bloom 0.5, Cal-Mag 1 / 0.5. Veg 2 / 4 / 2 (1-2-1), Cal-Mag 3 / 1. Bloom 2 / 1 / 4 (1-1-2), Cal-Mag 3 / 1.
Per 1 gallon — Fox Farm: nutes in teaspoons, Cal-Mag still in ml. Seedling Grow Big 0, Tiger 0, Big Bloom 0.5 tsp, Cal-Mag 1 / 0.5 ml. Veg Grow Big 1 tsp, Tiger 0, Big Bloom 1.5 tsp, Cal-Mag 4 / 1 ml. Bloom Grow Big 0, Tiger Bloom 1.5 tsp, Big Bloom 2 tsp, Cal-Mag 4 / 1 ml.
The filter is labeled All Strains (50). Filter first, then pick a name.
Each card shows lineage, THC, yield, flower time, difficulty, height, effect, terpenes, and a short grower note. Use this before you spend a seed.
The filter label says ALL STRAINS (50). The built-in list currently has 52 named cards — use the label on screen, not a head count. A strain can sit in more than one filter (Northern Lights Auto is beginner + medicinal). Some cards have no category and only show under All. This is a reference library, not a seed shop. Flower weeks on a card are a hint; Main Deck and Feeding Schedule use the cycle you type, not the card.
How to train an auto without wrecking it.
Claimed LST yield bump in the app is about 10–30% from even light. Topping risk called out: lost veg, stall, herm risk. Exception line is for experienced growers on fast-vegging cultivars only — default advice is still do not top.
Something looks wrong. Pick the symptom. The right card writes a diagnosis and the fix. It uses the medium from Gear Locker, so coco advice and soil advice are not the same.
Symptoms: overall yellow, lower yellow, new-growth yellow, brown/rust spots, clawing, tacoing, purple stems, brown slimy roots, stunted, burnt tips, droop.
Under that is preventive maintenance for coco/hydro, soil, and all systems.
Examples of medium split: overall yellow in coco/hydro is treated as pH lockout; in soil as nitrogen. Brown spots in coco/hydro = Cal-Mag (3–4 ml/gal in the prescription); in soil = potassium or pH. Purple stems can be genetics or phosphorus. Clawing and tip burn both say half-strength. Tacoing = light/heat (raise light, stay under 85°F). Droop asks wet vs dry before you add water. Med Bay’s coco/hydro maintenance card says water 65–72°F; the DWC Manager card says 65–68°F optimal and 72°F+ danger — both lines are in the app.
Free tier: 3 scans stored as growmaster_med_scans. After that, Activate License or buy Pro.
Type tent length, width, height. Say if you have a carbon filter and how many duct bends. Tap Calculate. You get minimum CFM and a fan size (4", 6", or 8").
Rule of thumb in the app: 4" for 2×2 / 2×4, 6" for 3×3 / 4×4, 8" for 5×5. Buy one size up and run it on a speed controller if you can.
What Calculate actually runs: CFM = (L × W × H) × air exchanges, then × 1.25 if the filter dropdown is YES, then a bend multiplier from the dropdown: 0 bends ×1.0, 1–2 bends ×1.2, 3–4 ×1.3, 5+ ×1.4. Exchange choices: 0.5 / 1 (default) / 2 / 3. Defaults on the form: 4 × 2 × 6 ft, 1 exchange, filter yes, 1–2 bends. Gear Locker tent size is not copied into these boxes.
Fan pick from that CFM: ≤200 → 4" (~190). ≤450 → 6" (~400). ≤800 → 8" (~700). Above that → 8"+ / multiple fans. Result also prints tent volume in cu ft.
The Ventilation Guide card on the same page says “each 90° bend +10%” and “long duct +5% per 10 ft.” That paragraph is not what the button uses. The button never adds a duct-length term. Trust the dropdown math above.
For buckets / reservoirs only. Enter gallons, plant count, and last water change. Tap Update Reservoir. Next change is set 7 days later. You also get gallons per plant and a daily top-off estimate (about 0.5 gal per plant).
Log pH and EC when you measure. Targets on the page: water 65–68°F, danger 72°F+, pH 5.8, EC 0.8–1.5 (half-strength auto). Full change every 7–14 days. Top off with plain water — do not add nutes to the top-off.
Status math: next change = last change + 7 days (the maintenance card still says 7–14). Gallons per plant = reservoir ÷ plant count. Daily top-off estimate = ceil(0.5 × plants). pH/EC log keeps the last 10 readings in this tab only — refresh clears it. Maintenance card: full drain 7–14 days, top off with plain water, 10% bleach clean then rinse, air stones every 2–4 weeks / replace ~6 months, optional Hydroguard / Voodoo Juice / Great White after a change.
Write what happened. Date, optional plant name, type (observation, feeding, training, issue, milestone), and notes. Check off milestones from germination through cure. Export to a text file when the run is done.
Entries live in this browser tab only. They are not written to localStorage. Refresh or close the tab and the log is gone unless you already hit Export. File name is grow-journal.txt. Header: “GROWMASTER UNIVERSAL - PLANT JOURNAL EXPORT”. Milestone checkboxes also reset on refresh. Export before you leave if you need a paper trail.
What the light actually costs. Pick wattage, hours per day (24/0, 20/4, or 18/6), and your electric rate in cents per kWh. You get daily, weekly, monthly, and a per-grow number. That per-grow figure is a 90-day estimate, not your Main Deck countdown.
Daily $ = (watts / 1000) × hours/day × (cents per kWh / 100). Weekly = daily × 7. Monthly = daily × 30. Per grow = daily × 90. That 90-day window is fixed in the calculator — it does not read the Main Deck cycle (56–84 days). Defaults: 12¢/kWh, 20 hours, 250W unless Gear Locker already set wattage. Comparison table is 250 / 400 / 600 / 1000W at the same hours and rate, monthly only. Light power only — not HVAC, fans, or nutrients.
Optional shopping list, not a checkout inside the app. Nutrient brands, the “magic mix” (70% coco / 20% vermiculite / 10% worm castings), tents/lights, and starter-kit size notes (2×2, 2×4, 4×4).
Some links are affiliate links. The app says that on the page. You do not need this screen to run a grow.
Brands listed: Botanicare, General Hydroponics, Fox Farm, Wiggle Worm, Vivosun, Spider Farmer, AC Infinity, Mars Hydro. Treat prices on that page as ballpark, not a live catalog.
Left menu → Activate License. Paste the key from the purchase email. You should see Pro License Active at the top of the menu.
Gold PRO on the button means that tool is part of the one-time unlock. Free still has Main Deck, germ, vault, training, harvest, and three Med Bay scans.
Yes. Use the menu button. Add it to your home screen if you want; it is built to work offline after you open it once.
Pinch the screen and pull your fingers apart to zoom in on any part of the app. Pinch back in to zoom out. That makes the text bigger wherever you need it.
No account. Grow data is not sent to us. The journal is session-only — hit Export if you want a file you can keep. Pro Gear Locker settings and your license stay in this browser until you clear site data.