Grow Diary: From Seed to Harvest — Complete Guide

A grow diary is the single most valuable tool for improving your results over time. Every harvest teaches you something — but only if you recorded what happened along the way. GrowVPD Pro's diary tracks climate, nutrients, photos, and harvest data across your entire grow cycle, then lets you compare grows side by side to see what actually made a difference.

Why Track Your Grow?

If you have ever wondered why one grow turned out better than another, the answer is usually hidden in the daily details. Growers who keep diaries consistently report better yields because they can:

• Identify what works — correlate specific nutrient schedules, VPD ranges, or training techniques with better outcomes
• Spot problems early — a sudden drop in pH or a week of high VPD shows up clearly in your data history
• Predict harvest timing — by comparing the current grow to past grows of the same variety, you can estimate how many weeks remain
• Share meaningful results — instead of guessing, you can show exact conditions that led to a particular yield
• Build a personal database — over several grows, you develop variety-specific knowledge that no generic guide can provide

Creating a New Grow

Open the Diary tab and tap the + button. The grow setup asks for the basic information about your plant:

• Name — give your grow a descriptive name (e.g., "Cherry Tomatoes #3 - Summer 2026")
• Variety — the specific variety you are growing
• Type — photoperiod or autoflower (this affects stage suggestions and light schedule recommendations)
• Medium — soil, coco coir, DWC, NFT, rockwool, perlite, or custom substrate
• Pot size — in liters or gallons
• Plant count — how many plants in this grow
• Water type — tap, RO, distilled, rain, spring, or filtered

Using Grow Templates

GrowVPD Pro includes pre-built templates with weekly VPD, temperature, humidity, and light targets for different growing styles. When you create a new grow, you can optionally select a template. The template provides week-by-week guidance: recommended VPD range, PPFD levels, nutrient strength, and more. You are free to deviate from the template — it serves as a starting reference, not a rigid schedule.

Assigning to a Tent

If you have set up a tent in the Automation tab, you can link your grow to it with Assign Grow in the tent's settings (a grow whose tent name matches the tent is linked automatically). This connects the grow to that tent's devices: if the tent has sensors, new diary entries are pre-filled from them.

Adding Daily Entries

The heart of the diary is the daily entry. You do not need to fill in every field every time — record what matters to you and what you have time for. Over time, even partial entries build a valuable history.

Climate Data

• Temperature — current air temperature (°C or °F)
• Night temperature — temperature during lights-off (important for the day/night differential)
• Humidity — relative humidity percentage
• VPD — automatically calculated from temperature and humidity; you do not need to enter this manually

Tip: If your grow is linked to a tent with smart sensors (for example Tuya or Bluetooth sensors), the app can auto-fill climate data from the last sensor reading. This saves time and ensures accuracy — no more squinting at a hygrometer across the tent.

Light Data

• PPFD — light intensity at canopy level in μmol/m²/s
• Light hours — photoperiod (e.g., 18/6, 20/4, or 12/12)
• Light distance — distance from light to canopy in cm or inches
• Light power — dimmer percentage if applicable

Water and Nutrients

• Water amount — total ml or liters given
• Water temperature — important for hydro setups (ideal: 18–22°C)
• pH — input pH of your feed water
• EC / PPM — nutrient concentration (two separate fields: fill in whichever your meter shows)
• Nutrients — pick products from the built-in database of 287 nutrient products from 18 brands. Each product is added with the manufacturer's recommended dose per litre, which you can adjust; the nutrient calculator in the Calculator tab works out the amounts for your whole tank.

Plant Data

• Height — plant height in cm (tracking the stretch during flowering is particularly useful)
• Technique — record training methods applied: topping, FIMming, LST, supercropping, defoliation, lollipopping, mainlining, ScrOG

Photos and Videos

Add photos directly from your camera or gallery. The diary builds a visual timeline of your grow, which is invaluable for tracking plant health and development. You can also add short video clips (Pro). All media is stored locally on your device — nothing is uploaded to any server; photos are only copied to your own devices if you pair them for sync.

Privacy feature: GrowVPD Pro (with the Pro upgrade) can hide grow photos from your device's gallery. Photos are stored in the app's private directory and do not appear in Google Photos or any other gallery app. There is also a stealth mode that hides notifications and the app preview in the task switcher, and a disguised icon option that makes the app look like a calculator.

Notes

Free-form text for anything else: observations about leaf color, pest sightings, environmental changes, equipment adjustments, or reminders for next time. Notes are searchable, so write whatever comes to mind.

Growth Stages

Each entry is tagged with a growth stage. GrowVPD Pro uses seven stages:

1. Germination — from sowing until the seedling breaks through the surface
2. Seedling — from germination until the first true leaves develop (typically 1–2 weeks)
3. Vegetative — active foliage growth under long light hours (18/6 or 20/4)
4. Pre-flower — the first 1–2 weeks after flipping to 12/12 (the "stretch" period)
5. Flower — bud development and maturation
6. Late flower — the final weeks including flush and ripening
7. Harvest — chop day and drying/curing period

The stage affects VPD recommendations (seedlings need higher humidity), template targets, and automation rule filters. You can change the stage at any time as your plant progresses.

Harvest Tracking

When you reach harvest, GrowVPD Pro provides a dedicated harvest entry with fields for:

• Wet weight — total weight immediately after chop (per plant or total)
• Dry weight — weight after drying (the number that matters)
• Trim method — wet or dry trim
• Flush days — how many days you flushed before harvest
• Trichome state — clear, cloudy, amber, or mixed at harvest

The app automatically calculates efficiency metrics from your harvest data:

• Grams per watt — dry weight divided by light wattage (the standard efficiency benchmark; part of the Pro analytics, shown when the app knows your light's wattage)
• Grams per plant — average yield per plant
• Total yield — combined dry weight
• Drying ratio — wet-to-dry weight ratio (typically 3:1 to 5:1)

Comparing Grows

Once you have completed two or more grows, the Compare Grows feature lets you view them side by side. Select two to eight grows and compare them week by week and stage by stage: temperature, humidity, VPD, nutrients, height, and yield. This is the fastest way to understand what changed between a good grow and a great one.

The comparison view marks the better value for metrics such as yield and efficiency, and if one grow had consistently higher VPD during weeks 4–6 of flowering, the chart makes that obvious at a glance.

Week Navigator

For long grows, the week navigator lets you jump to any week quickly. It shows a horizontal row of week buttons, color-coded by stage. Tap any week to scroll directly to those entries. This is especially useful during flowering when you want to check back on what happened two weeks ago.

Smart Sensor Integration

If you have connected smart devices in the Automation tab, your diary benefits automatically:

• Auto-fill climate data — when creating a new entry, the app pre-fills temperature, humidity, and VPD from the most recent sensor reading for your tent
• PPFD from smart sensors — if a sensor in the tent reports light intensity (PPFD), that value is pre-filled too
• Camera snapshots — Tuya cameras can automatically capture daily photos and save them to your diary
• Grow-to-tent linking — when your grow is assigned to a tent, sensor data is automatically associated with the correct grow

Exporting Your Diary

GrowVPD Pro offers two export formats (Pro feature):

• PDF report — a formatted document with all entries, nutrients, photos, and the harvest summary. Ideal for sharing or archiving.
• JSON data export — raw data in JSON format for growers who want to analyze their data in spreadsheets or custom tools.

Tip: Export a PDF after every completed grow and save it to your cloud storage. Even if you switch phones, you will always have a record of your grow history. The PDF includes all photos at reduced resolution to keep the file size manageable.