Why Record Harvest Data?

The harvest is the culmination of weeks or months of work. Without recording the results, you have no way to objectively compare grows, measure the impact of changes, or identify what works best for your setup. "That grow felt better than the last one" is not data. 487g dry from 4 plants under 480W in 63 days of flower — that is data you can learn from.

Recording Harvest in GrowVPD Pro

When you are ready to harvest, change the stage in your diary entry to "Harvest." The app presents harvest-specific data fields:

Wet Weight

Weigh your freshly cut and trimmed buds immediately after harvest, before any drying. This is the wet weight. It gives you an immediate sense of volume, but it is not the final number — roughly 75–80% of wet weight is water.

Dry Weight

After drying (typically 7–14 days at 60% RH and 18–21°C), weigh the buds again. This is your dry weight — the actual yield. This is the number used for all efficiency calculations.

Tip: A healthy wet-to-dry ratio is 4:1 to 5:1. If your dry weight is less than 20% of wet weight, you may have over-dried or had small, airy buds. If it is more than 30%, the buds may not be fully dry and risk mold in storage.

Key Efficiency Metrics

GrowVPD Pro automatically calculates these metrics when you enter harvest data:

Grams per Watt (g/W)

The most common yield efficiency metric. Divide your total dry weight by the wattage of your grow light.

Example: 450g dry / 480W LED = 0.94 g/W

  • Below 0.5 g/W: Room for improvement. Check your VPD, light distance, nutrition, and training.
  • 0.5–1.0 g/W: Good. Most hobby growers land here.
  • 1.0–1.5 g/W: Excellent. Optimized environment and genetics.
  • Above 1.5 g/W: Exceptional. Usually involves CO2 supplementation and perfect environment control.

Grams per Plant (g/plant)

Total dry weight divided by number of plants. Useful for comparing different plant counts in the same tent.

Example: 450g / 4 plants = 112.5 g/plant

This metric is heavily influenced by training method, veg time, and pot size. A single plant grown for 8 weeks in veg with heavy LST can yield as much as 4 plants with 3 weeks of veg.

Grams per Square Meter (g/m2)

Total dry weight divided by the grow area footprint. This normalizes for tent size and lets you compare efficiency across different setups.

Example: 450g / 1.44 m2 (120x120 cm tent) = 312 g/m2

Days to Harvest

Total number of days from seed (or clone) to chop. GrowVPD Pro calculates this automatically from the grow start date to the harvest entry date. Compare across strains to understand which genetics finish faster.

What the Data Tells You

Compare Across Grows

After 3–4 completed grows, patterns emerge. You might discover that:

  • Your yields are always better in winter (lower ambient temp = better late flower conditions)
  • A particular strain consistently outperforms others in your setup
  • Switching from 4 plants to 2 plants with longer veg time produced the same yield with less work
  • Your g/W improved after you started monitoring VPD and maintaining it in the target range

Identify the Impact of Changes

When you change one variable between grows (new light, different substrate, added CO2), the harvest data shows whether the change helped. This only works if you record everything else too — which is why consistent diary entries throughout the grow are essential.

Tip: Use GrowVPD Pro's grow comparison feature to put two grows side by side. The app shows differences in VPD averages, PPFD levels, nutrients, and harvest metrics on a single screen, making it easy to spot what changed.

Drying Tips That Protect Your Yield

Drying is part of the harvest, and doing it wrong can ruin an otherwise excellent grow:

  • Temperature: 18–21°C (64–70°F). Lower temperatures preserve terpenes.
  • Humidity: 55–65% RH. Too dry (below 50%) causes buds to dry too fast, trapping chlorophyll and producing a harsh smoke. Too humid (above 70%) risks mold.
  • Airflow: Gentle, indirect. Do not point fans at the buds. You want air circulation in the room, not a wind tunnel.
  • Duration: 7–14 days. The buds are ready when small stems snap instead of bending, and the outside feels dry but the bud still has slight give when squeezed.
  • Darkness: Dry in a dark room. Light degrades THC and terpenes.
Do not rush drying. Fast-drying in 3–4 days (by raising temperature or lowering humidity) destroys terpenes and produces harsh, grassy-tasting flower. The slow dry is where quality is made.

Recording in the App: HarvestSheet

The fastest way to log a harvest in GrowVPD Pro is the Harvest button on the grow detail screen. Tap it and the HarvestSheet slides up — one screen with every field you need:

  1. Harvest date — defaults to today, but you can backdate if you forgot to log on the actual day.
  2. Wet weight — enter the post-trim weight in grams (or ounces, if you have your unit set to imperial).
  3. Dry weight — leave blank if you are still drying; come back and edit later.
  4. Notes — freeform field for trim impressions, smell, anomalies, anything you want to remember.

Tap Save harvest and the sheet calculates everything from your existing grow data: cycle time, yield per plant, g/W, g/m², and the wet/dry ratio.

Cycle time calculation

The app computes cycle time as (harvest date) − (grow start date), in days. If you have a strain assigned to the grow, the cycle time is also compared to the strain’s expected duration so you can see whether you finished early or late.

Yield per plant + wet/dry ratio

Yield per plant divides dry weight by the plant count recorded on your grow. The wet/dry ratio is calculated automatically and flagged in three colors:

  • Green (4:1 to 5:1) — healthy ratio, well-dried.
  • Amber (3:1 or 6:1) — possibly under- or over-dried.
  • Red (less than 3:1 or more than 6:1) — investigate. Either the wet weight was off, the buds dried too hard, or there’s still moisture trapped inside that risks mold.

Editing an existing harvest

You can edit a harvest at any time. Open the grow detail, scroll to the HarvestStatsCard, tap Edit harvest, and the same HarvestSheet opens with current values pre-filled. Common reasons to edit:

  • Adding the dry weight after the cure (the most common).
  • Correcting a typo in wet weight.
  • Adding a curing-stage entry (separate from harvest) to track how the buds developed during cure.

Status timeline events

Saving a harvest writes a HARVEST event to the GrowStatusEvent timeline visible at the top of the grow detail. When you later mark the grow as cured, that adds a CURED event. The timeline gives you an at-a-glance lifecycle view: created → stage changes → harvested → cured.

PDF export with lifecycle + harvest summary

From the grow detail menu (three-dot top right), tap Export PDF. The exported PDF includes:

  • Cover page with strain, dates, plant count, total cycle days.
  • Lifecycle timeline showing every status event with timestamps.
  • Stage-by-stage summary of average VPD, temperature, humidity, light hours.
  • Harvest summary card: wet/dry weights, all efficiency metrics, wet/dry ratio with verdict.
  • Daily entries with notes, sensor data, and embedded photos.
  • Optional cure notes if filled in.

The PDF is great for sharing with friends, attaching to a forum post, or archiving when you stop running the tent for a season. Long-term diary data also exports to JSON if you prefer raw data.