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 around 60% RH and 15–18°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 calculates grams per plant and the days to harvest when you enter harvest data, and grams per watt in the Pro analytics; grams per square meter is quick to work out yourself:

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 date you record. Compare across varieties 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 variety 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: 15–18°C (60–65°F). Lower temperatures preserve terpenes.
  • Humidity: 55–65% RH. Too dry (below 50%) causes buds to dry too fast, trapping chlorophyll and leaving a harsh taste. 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 terpenes.
Do not rush drying. Fast-drying in 3–4 days (by raising temperature or lowering humidity) destroys terpenes and produces harsh, grassy-tasting buds. The slow dry is where quality is made.

Recording in the App: Mark as Harvested

The fastest way to log a harvest in GrowVPD Pro is Mark as harvested on the grow’s diary page. Tap it and the Harvest form opens — 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.
  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 and a harvest summary card appears on the grow, calculated from your existing grow data: cycle time, total yield, yield per plant, and the wet/dry ratio.

Cycle time calculation

The app computes cycle time as (harvest date) − (grow start date), in days.

Yield per plant + wet/dry ratio

Yield per plant divides the harvest weight (the dry weight once you have entered it) by the plant count recorded on your grow. The wet/dry ratio is calculated automatically; as a rule of thumb:

  • 4:1 to 5:1 — healthy ratio, well-dried.
  • Around 3:1 or 6:1 — possibly under- or over-dried.
  • Below 3:1 or above 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, find the harvest summary card, tap Edit harvest, and the same form 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 marks the grow as Harvested on the stage timeline at the top of the grow. The timeline gives you an at-a-glance lifecycle view: created → stage changes → harvested.

PDF export with lifecycle + harvest summary

Open the grow’s diary and choose Export PDF (the PDF icon above the entries on Android). The exported PDF includes:

  • A header with the grow name, start date, variety, medium, pot size, and plant count.
  • Lifecycle timeline showing every stage event with its date.
  • A table of your diary entries with temperature, humidity, VPD, pH, EC, PPFD, water, and height.
  • Harvest summary: wet/dry weights, cycle time, yield per plant, and the wet/dry ratio.
  • Nutrients, training techniques, and your photos.

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.