Grow Diary Granddaddy Purple

Granddaddy Purple – Week #4 of Flower (Mid Flower)

Week #4 marked the first week of mid flower for both GDP plants. Vertical growth fully ceased last week, and energy is now directed toward bud bulking and resin production. Bud mass increased noticeably this week, with tighter stacking across the main colas and secondary branches. Several branches are beginning to lean under weight gain, signaling the start of structural loading earlier than expected.

Light intensity across the canopy is holding steady at 950–975 PPFD with a DLI of 42. UV-A exposure was increased to 2 hours per day, coinciding with a visible uptick in trichome density on sugar leaves and upper bracts. Aroma intensified dramatically this week, progressing to a strong skunky-citrus profile that has begun overpowering the carbon filter and filling the lung room.

Environmental conditions stayed well controlled despite external weather challenges. Daytime temperatures averaged ~75°F with nighttime lows around 66°F, maintaining an average VPD of ~1.3 (range 1.2–1.4). A winter storm earlier this week caused outdoor temperatures to drop below zero, and while tent air temperatures remained stable, part of the root zone of each plant nearest the bottom vents dropped into the mid-50s. No stress responses were observed - water uptake remained strong, leaves stayed turgid, and growth continued uninterrupted.

Feeding continued at 1–1.25 gallons per plant every other day, using strictly mid-bloom nutrients at a medium GH concentration (~900 ppm). pH remained stable at 6.1, with 5 ml/gal Cal-Mag and 1 ml/gal silica applied once weekly. Nutrient response remains clean with no signs of deficiency or imbalance.

Defoliation was minimal this week, limited to a small number of leaves removed only where contact or airflow restriction occurred. Nearly all canopy cleanup was completed prior to mid flower, leaving an open, well-ventilated structure that continues to support even light distribution and healthy bud development.

By the end of Week #4, both GDP plants are firmly established in mid flower: buds stacking and swelling, resin production accelerating, aroma intensifying, and overall plant health remaining excellent despite brief root-zone temperature fluctuations.