# Grow journal 101: what to log and why

> A grow journal is a dated record of what you did and what the plant did: daily climate and watering, weekly photos, pH, EC and height, and every event (germination, transplant, topping, flip, first pistils, problems, harvest weights). Log both days since flip and days of flower. On GenetixBay, a journal tied to a GB-ID links your harvest back to the seed pack, and herm reports and results feed the open record other growers rely on.

- Canonical: https://genetixbay.com/knowledge/guides/grow-journal-101.html
- Category: Start here · Level: Beginner
- Evidence: Grower practice · Status: Draft: awaiting expert review
- Stage: Any stage · Systems: Any system
- Updated: 2026-10-31 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Questions and answers

**What should I write in a grow journal?** A grow journal should log, every day, the date, lights-on and lights-off temperature and [RH](https://genetixbay.com/knowledge/glossary/relative-humidity.md), and any watering or feeding with volume, [pH](https://genetixbay.com/knowledge/glossary/ph.md) and [EC](https://genetixbay.com/knowledge/glossary/ec.md); every week, [photos](https://genetixbay.com/knowledge/glossary/photoperiod.md) from the same angle, plant height and [runoff](https://genetixbay.com/knowledge/glossary/runoff.md) readings; and every event: [germination](https://genetixbay.com/knowledge/glossary/germination.md), transplant, training, the flip, first [pistils](https://genetixbay.com/knowledge/glossary/pistil.md), any problem and fix, harvest, wet and dry weight, and cure notes. Always write down the seed source and batch.

**Why should I keep a grow journal?** Keep a grow journal because it is the only way to learn from a grow: when a problem shows up, the log tells you what changed three to five days earlier. It also lets you repeat what worked, predict harvest dates for a cultivar, and prove what a line did. On GenetixBay, journals link harvests to seed packs and turn individual grows into open, shared evidence.

**Why log both days since flip and days of flower?** Log both because the flip isn't day 1 of flower. After switching to 12/12 there is a transition of about 10–14 days before the first pistil clusters appear, and breeder flowering times usually count from those pistils. Logging the flip date and the first-pistil date shows your cultivar's real transition and makes harvest dates predictable.

**How often should I take grow photos?** Take photos at least once a week from the same angle, distance and light, and also at every event: before and after training, at the flip, at first pistils, whenever something looks wrong and at harvest. Switch coloured grow lights to white or off for photos so leaf colour is true. Close-ups of a problem should show both old and new growth.

**What is a [GB-ID](https://genetixbay.com/knowledge/glossary/gb-id.md) in a grow journal?** A GB-ID is GenetixBay's permanent identifier for a line, [seed batch](https://genetixbay.com/knowledge/glossary/seed-run.md), plant, grow or harvest. Tying a journal to the GB-ID of the seed batch links the harvest, photos, problems and any herm report back to the exact seed pack, so the record never gets lost or renamed and other growers can see how that batch really performed.

**Should I report a hermaphrodite in my journal?** Yes. Log any intersex flower with the date, days since flip, where on the plant it appeared, how many flowers, and the conditions that week (light leaks, heat). On GenetixBay these herm reports count towards the [herm threshold](https://genetixbay.com/knowledge/glossary/herm-threshold.md): a line showing more than 2 % intersex plants in tester grows cannot join [Bay Lines](https://genetixbay.com/knowledge/glossary/bay-lines.md), [the Seed Club](https://genetixbay.com/knowledge/glossary/seed-club.md) or be featured.

**Short answer.** A [grow journal](https://genetixbay.com/knowledge/glossary/grow-journal.md) is a dated record of what you did and what the plant did. Log **daily** climate and any watering or feeding (volume, pH, EC), **weekly** photos, height and runoff, and **every event**: germination, transplant, training, the flip, first pistils, problems, [harvest weights](https://genetixbay.com/knowledge/glossary/yield.md) and cure notes. Log both **days since flip** and **days of flower**. On GenetixBay a journal tied to a [GB-ID](https://genetixbay.com/knowledge/glossary/gb-id.md) links your harvest back to the seed pack.

## Why keep a grow journal at all?

Keep a journal because it is the only reliable way to learn from a grow. Plants answer slowly: a change in watering or feed shows on new growth 3–5 days later, and memory blurs in that time. A dated log turns "something went wrong in week 6" into "I raised the EC on day 38 and the tips burned on day 41". It is also the base of a clean diagnosis: the [diagnosis order](https://genetixbay.com/knowledge/diagnosis/how-to-diagnose-any-problem.md) starts with what changed.

A journal is also evidence. Strain names alone are unreliable guides to what is in the pack, and genetic studies have found plants sold under one name that don't match each other [4]. A record of what a seed batch actually did, by many growers, is worth more than any description.

## What do you need to keep a journal?

You need a place to write and a few instruments you already own for the grow.

- [ ] A notebook, a spreadsheet or a GenetixBay journal (pick one and stick to it)
- [ ] A phone or camera for photos, and a plain white or neutral light for true colour
- [ ] A thermo-hygrometer with min/max memory (a logging sensor is even better)
- [ ] Your pH and EC meters, calibrated ([pH made simple](https://genetixbay.com/knowledge/guides/ph-made-simple.md))
- [ ] A measuring jug and a tape measure
- [ ] A kitchen scale in grams for pot weight and harvest weight
- [ ] Plant labels with a short ID per plant (P1, P2…) and the seed batch

## What should you log, and how often?

Log a small, fixed set of readings on a fixed rhythm. Consistency beats volume: the same five numbers every day are worth more than a long note once a fortnight.

| When | What to log | Example |
|---|---|---|
| **Once, at the start** | Seed source, cultivar name as sold, batch or GB-ID, seed type ([feminised](https://genetixbay.com/knowledge/glossary/feminised-seed.md), regular, auto), number sown, medium, [pot size](https://genetixbay.com/knowledge/glossary/pot-size.md), light model class and wattage, tent size | "Batch GB-…; feminised photo; 3 sown; 15 L fabric pots; coco/perlite 70/30; 240 W [LED](https://genetixbay.com/knowledge/glossary/led.md); 80 x 80 cm" |
| **Daily** | Date, day count (from germination; from flip after the flip), lights-on and lights-off temperature and RH (or min/max), anything you did | "Day 23. 26.1 / 21.4 °C, 62 / 70 %. Watered 1.2 L, pH 6.0, EC 1.2, runoff 15 %" |
| **Each watering or feed** | Volume in, pH in, EC in, runoff %, runoff pH and EC if measured, pot weight before | "1.5 L in, pH 6.1, EC 1.4; runoff 200 mL, EC 1.9" |
| **Weekly** | Photos from the same angle, height in cm, node count or canopy notes, PPFD at canopy if you can measure it, pest check result | "Week 5: 38 cm, 7 nodes, no pests on 10 leaves" |
| **Events** | Germination, transplant, topping, LST start, defoliation or tucking, light changes, the flip, first pistil clusters, sex confirmed, any intersex flower, problems and the fix, harvest | "Flip: day 42. First pistils: day 12 since flip" |
| **Harvest** | Date, days since flip and days of flower, trichome mix, wet weight per plant, dry weight, drying days and room averages | "Day 67 since flip / day 55 of flower; 1 clear / 7 cloudy / 2 amber; 412 g wet, 96 g dry, 11 days at 18 °C / 58 %" |
| **Cure** | Jar date, equilibrated jar readings, burp schedule, smell and smoke notes at 2, 4 and 8 weeks | "Week 2: 60 %, sweet and sharp" |

## How do you start a journal, step by step?

Set the journal up before the seeds go in, so day 0 is recorded too.

1. **Pick one format:** a paper notebook, a spreadsheet with the columns above, or a GenetixBay journal.
2. **Record the setup:** tent size, light and its height, fan, pot size, medium and nutrient.
3. **Record the genetics:** where the seed came from, the name as sold, the batch or GB-ID, the seed type and how many you sow. Photograph the pack.
4. **Run the empty room for 48 h** and log day and night temperature and RH. That's your baseline ([climate basics](https://genetixbay.com/knowledge/guides/climate-basics-vpd-cheat-sheet.md)).
5. **Label every plant** (P1, P2…) and keep the label with the plant all the way to the jar.
6. **Log daily** in under two minutes: climate, what you did, one line on how the plants look. The [daily five-minute check](https://genetixbay.com/knowledge/guides/daily-five-minute-check.md) is a good moment.
7. **Photograph weekly** from the same spot, under white light.
8. **At the flip, start a second day counter.** Then note the date of the first pistil clusters at the tops: that's day 1 of flower.
9. **Log every problem** as symptom, location (old or new growth), date, suspected cause, the one change you made, and the result 3–5 days later.
10. **Close the journal** with harvest, dry and cure data and a short verdict: would you grow this batch again, and what will you change?

## Why log days since flip and days of flower?

Log both because the flip isn't day 1 of flower. In controlled studies the first real flowering at the top of the plant came about 8–14 days after short days began, around 13–14 days on average and up to three weeks in slow cultivars [2]. Breeder flowering times usually count from those first pistils. That's the GenetixBay house position, and journals and Jardin track both counters. Over a few runs your journal will show your cultivar's real transition and make harvest predictable ([the flip-to-flower transition](https://genetixbay.com/knowledge/environment/flip-to-flower-transition.md), [photoperiod grow calendar](https://genetixbay.com/knowledge/guides/photoperiod-grow-calendar.md)).

## How do GenetixBay journals use your records?

GenetixBay journals turn single grows into shared, open evidence. Three things matter for a beginner:

- **GB-ID links the harvest to the seed pack.** Tie the journal to the seed batch's GB-ID and your photos, problems and results stay attached to that exact batch, so names and renames can't lose the record [1]. See [documenting lineage evidence](https://genetixbay.com/knowledge/breeding/documenting-lineage-evidence.md).
- **Herm reports feed the herm threshold.** Log any intersex flower with date, days since flip, location and conditions. Hermaphroditism has real consequences for seed and progeny [3], and GenetixBay holds lines to a [herm threshold](https://genetixbay.com/knowledge/glossary/herm-threshold.md) of 2 % in tester grows for Bay Lines, the Seed Club and featuring. See [telling sex and spotting herms](https://genetixbay.com/knowledge/guides/telling-sex-and-spotting-herms.md).
- **Side-by-side records feed open research.** [Bay Trials](https://genetixbay.com/knowledge/glossary/bay-trials.md) are member-run controlled comparisons that settle grow myths with data. A clean journal with one variable changed between two plants is the seed of a trial. See [Mythbusters](https://genetixbay.com/knowledge/mythbusters.md).

## How will you know it's working?

You'll know your journal is working when:

- You can answer "what changed three days before this problem?" in under a minute.
- Your second run of a cultivar hits harvest within a few days of the date your first run predicted.
- Weekly photos show a clear story when scrolled in order.
- You stop repeating the same mistake twice.

## What mistakes do beginners make with journals?

Beginners mostly stop logging when things go well, or log too much and burn out.

- **Logging only when there's a problem,** so there's no baseline to compare against.
- **No seed source or batch recorded,** so the result can't be traced to the pack.
- **Counting the flip as day 1 of flower.**
- **Photos under purple light** or from a different angle each time.
- **Changing several things at once** and logging them as one event.
- **Writing "fed" instead of volume, pH and EC.**
- **Not recording harvest weights and drying conditions,** the data that links method to result.
- **Renaming a cultivar** in your notes; keep the name as sold plus the batch ID ([record-keeping and naming ethics](https://genetixbay.com/knowledge/breeding/record-keeping-naming-ethics.md)).

## Evidence

- Strain names are unreliable without records: *Supported* by genetic studies [4].
- Naming and record conventions for cultivated plants: *Established* code [5].
- The 10–14 day transition after the flip: *Supported* [2]; house position.
- Hermaphroditism affects seed and progeny: *Supported* [3]; GenetixBay's 2 % herm threshold is house policy.
- GB-ID provenance model: GenetixBay documentation [1].
- What and how often to log: *Grower practice*.

## Sources

1. GenetixBay. GB-ID provenance model, 2026. https://genetixbay.com/how-it-works
2. Zhang M, Anderson SL, Brym ZT, Pearson BJ. 2021. Photoperiodic flowering response of essential oil, grain, and fiber hemp (Cannabis sativa L.) cultivars. Frontiers in Plant Science 12:694153. https://doi.org/10.3389/fpls.2021.694153
3. Punja ZK, Holmes JE. 2020. Hermaphroditism in marijuana (Cannabis sativa L.) inflorescences: impact on floral morphology, seed formation, progeny sex ratios, and genetic variation. Frontiers in Plant Science 11:718. https://doi.org/10.3389/fpls.2020.00718
4. Schwabe AL, McGlaughlin ME. 2019. Genetic tools weed out misconceptions of strain reliability in Cannabis sativa: implications for a budding industry. Journal of Cannabis Research 1:3. https://doi.org/10.1186/s42238-019-0001-1
5. Brickell CD, et al. (eds). 2016. International Code of Nomenclature for Cultivated Plants, 9th edition. Scripta Horticulturae 18. ISHS. https://www.ishs.org/scripta-horticulturae/international-code-nomenclature-cultivated-plants-ninth-edition