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Granddaddy Purple Auto: Week-by-Week Grow Report
Key Takeaways
- This Granddaddy Purple Auto grow report follows a full 77-day cycle, from a difficult seedling stage to harvest, using real week-by-week data from the tent.
- Despite a slow and uneven start, the plant recovered well, stayed compact at 53cm, and developed dense, resinous flowers during an extended autoflowering run.
- Granddaddy Purple Auto produced 81g of dried bud from one small indoor plant, showing strong yield potential for compact grow spaces.
- Her indica-dominant genetics deliver fruity berry, herbal, and pine flavors alongside deeply relaxing, happy, and sleepy effects.
Contents:
- Granddaddy purple auto grow report: equipment list
- Granddaddy purple auto grow report: seedling stage (week 1)
- Granddaddy purple auto week-by-week grow guide: vegetative stage (weeks 2 to 4)
- Granddaddy purple auto grow report: flowering stage (weeks 5 to 11)
- Granddaddy purple auto grow report: harvest
- Granddaddy purple auto characteristics
Three autoflowers went into the tent on the same day, and this is the story of one of them. Alongside Pink Mist Auto and the old favorite Royal Cookies Auto, I planted a single Granddaddy Purple Auto from Royal Queen Seeds, and she turned out to be the one worth writing about at length.
This Granddaddy Purple Auto grow report pulls the whole cycle from GrowDiaries together in one place: the rocky first week, the unusually long stretch before flowering, the watering can, and the numbers I logged every step of the way. If you want to see what running this autoflower actually involves before you buy a pack, here is the real thing, week by week, finished off with the genetics, flavor and effects.
Granddaddy Purple Auto Grow Report: Equipment List
I kept the setup simple and let the genetics carry the run. Everything below stayed the same from seed to chop, so this doubles as the kit checklist for anyone using this Granddaddy Purple Auto grow guide to plan their own tent.
- Grow tent: Secret Jardin DS120W (120 x 60 x 178 cm), a 0.72 m² footprint
- Light: MIGRO ARAY 4, 240 W LED
- Extraction: TT Silent-M 100 fan with a Primaklima PK 100/125 carbon filter
- Circulation: an oscillating Koala fan
- Substrate: BioBizz Light-Mix
- Pots: 11 L fabric pots
- Seeds: Granddaddy Purple Auto by Royal Queen Seeds
- Nutrients: the RQS Organic range to start (Easy Boost Organic Nutrition, Easy Roots Mycorrhiza Mix, Seaweed), then CalMg with BioBizz Bio-Grow and Bio-Bloom, and Plagron Lemon Kick to manage pH
Granddaddy Purple Auto Grow Report: Seedling Stage (Week 1)
I dropped the seed straight into pre-mixed BioBizz Light-Mix in its final 11 L fabric pot. Autoflowers resent transplanting, so they go into their forever home from day one to spare the roots any setback. To wake up the soil life I charged the substrate with the RQS Organic range: 50 ml of Easy Boost Organic Nutrition, 5 ml of Easy Roots Mycorrhiza Mix to colonise the young roots, and 10 ml of Seaweed as a gentle tonic.
Within a few days the cotyledons were up and open, and the Granddaddy Purple Auto grow diary was properly under way. The first week ran at 18 hours of light, the lamp 35 cm above the canopy, days around 26 °C, nights at 23 °C, humidity at 50% and water at pH 6.0, with just 0.25 L per plant.
She looked strange to begin with. One side was stunted, so she sprouted leaves from three sides and sat distinctly lopsided. Day one was miserable to look at, yet by the seventh day she had perked up and measured around 4 cm. I gambled that the wonkiness would even out once she gained height, so I left her alone and let her sort herself out.
Granddaddy Purple Auto Week-by-Week Grow Guide: Vegetative Stage (Weeks 2 to 4)
This is where she tested my patience. Most autoflowers race into bloom, but this plant took nearly four weeks before showing her first flowers, and she came good after that wobbly start. Following Granddaddy Purple Auto week by week, the conditions held steady: 18 hours of light, the lamp 35 cm above the canopy, days around 26 to 27 °C, nights at 23 °C, humidity at 50%, and every feed dialled to pH 6.0.
Week 2
The second week turned things around. She did not stretch much, but she stacked new leaves and pushed out branches, and that stunted look was gone. The older growth was a deep dark green, the new growth a lighter shade. Watering settled to once every four or five days, with 5 L mixed for all three plants plus CalMg and Bio-Grow.
_1.webp "Granddaddy Purple Auto Week 2: Early Vegetative Growth")
Week 3
Steady progress. My autoflowers usually start showing pistils by now, but Granddaddy was still firmly in growth mode, building a full, even crown of healthy fan leaves with the early lopsidedness long forgotten. As the plants drank more, I lifted the watering to match.
.webp "Granddaddy Purple Auto Week 3: Vegetative Growth")
Week 4
A run this long before flowering is unusual for an auto, but this plant clearly needed it. She finally showed her first pistils, marking where the flowers would form, and put on 8 cm with a thick crown of dark green leaves and no sign of deficiency. Sitting shorter than her roommates, she went up on a stand to get closer to the light. Watering moved to every three days, roughly 9 L mixed for the three of them.
_6.webp "Granddaddy Purple Auto Week 4: First Pistils")
Granddaddy Purple Auto Grow Report: Flowering Stage (Weeks 5 to 11)
After that long start she flipped into bloom and stayed compact, pouring her energy into resinous flowers rather than height. The tent held the same numbers right through flowering: 18 hours of light, lamp at 35 cm, days at 27 °C, nights at 23 °C, humidity at 50%. The rest of this Granddaddy Purple Auto grow journal tracks her bloom one week at a time, and keeping honest grow reporting here meant weighing the watering can and measuring height every single week.
Week 5
She entered flowering at last, the longest pre-bloom stretch I have ever run on an auto. I put it down to that early deformation, but she now looked like a different plant, with flowers forming along the branches and foliage so thick the stem disappeared. CalMg, Bio-Grow and Lemon Kick continued as before.
Week 6
Still shorter than her roommates, so back up on the stand. By now she was a proper bush, leaves and branches too dense to see inside. I stripped the lowest leaves and branches at the base to make watering easier and keep air moving, and the canopy stayed a healthy dark green.
Week 7
Under 10 cm of growth this week, which was about right for her now. She had settled into a small, tightly packed bush. I pulled the odd leaf with yellow spots, mostly down low, but she looked healthy and the flowers were filling in nicely.
Week 8
Four weeks into bloom and the flowers were turning solid. At 53 cm she had topped out, a full 30 cm shorter than the Pink Mist beside her, so she stayed on the stand near the light. She held a chubby shape with the main stem buried under thick foliage, and the healthy green told me she wanted for nothing.
Week 9
The flowers firmed up and started to glisten with trichomes, the thick branches reading like a bouquet. The leaves lightened a touch, the first sign of approaching maturity. This is where I cut the nutrients and ran plain pH-balanced water for the final stretch.
Week 10
Ten weeks from sprouting. My plants are usually done by now, but Granddaddy wanted longer. She had filled in nicely, the buds giving off a clear fruity scent, with some leaves taking on a yellow fall tone. One more week, I reckoned. Pink Mist and Royal Cookies came down on day 70.
Week 11
The final week of bloom. The flowers were small but rock hard, caked in trichomes and giving off a full fruity smell, and the leaves had turned a deep fall yellow. After a last set of waterings on plain pH-6.0 water at days 72 and 75, she was ready for the chop.
Granddaddy Purple Auto Grow Report: Harvest
On day 77 she was ready, so I cut her at the base and hung her whole in the grow box to dry slowly before trimming and a proper cure. From seed to chop she ran roughly 11 weeks: a long seedling and vegetative stretch, then seven weeks of flowering.
The numbers tell the story. She never grew tall at 53 cm, but the branches were packed with flower, and a single plant gave me 81 g of dried bud from a 0.72 m² tent, a genuinely strong return for something this small. Over the cycle she took CalMg almost throughout, Bio-Grow in veg and Bio-Bloom in flower, then plain water for the last fortnight.
She knocked me out of my shoes. There were no real changes to my usual routine, yet she came out above average, and as an indica-dominant plant a short, flower-heavy build was exactly what I was after. That is the Granddaddy Purple Auto week-by-week run logged in full, from a wonky seedling to an easy 81 g and a 10/10 from me.
Granddaddy Purple Auto Characteristics
With the grow on record, here is what sits behind the genetics and what to expect in the jar.
Genetic Attributes of Granddaddy Purple Auto
Granddaddy Purple Auto is the autoflowering take on the iconic Granddaddy Purple. Royal Queen Seeds built her by crossing the original Granddaddy Purple with Big Bud Auto, and the lineage runs back through Purple Urkle (Afghan x Skunk) and a Mendocino Purps phenotype. The result is indica-dominant at roughly 75% indica, 20% sativa and 5% ruderalis, with THC reaching around 19% and low CBD, a profile that lands the full-bodied effects she is known for.
Growing Characteristics of Granddaddy Purple Auto
She is compact and forgiving, which is exactly why she suited a small tent, handing over 81 g from a single plant in well under a square metre. On paper, expect 70 to 120 cm indoors with yields of 375 to 450 g/m², or 80 to 140 cm outdoors returning 110 to 160 g per plant in a good summer. From germination to harvest runs roughly 70 to 85 days, with flowering around 55 to 60 days, though as my run showed a slow starter can stretch that out. Rated an easy grow, she likes warmth and a stable environment, and stays bushy and dense rather than stretchy, which makes her a sound pick for a newer grower.
Effects and Flavor of Granddaddy Purple Auto
On the smoke, she is deeply relaxing and tends to leave you feeling relaxed and happy, with a soothing, sleepy weight that sits at the indica end, though a gentle uplifting lift rounds it out. Plenty of growers keep an indica like her for the evening, when the aim is simply to switch off and settle.
The terpene profile is built on berry, fruit and herbal notes. Juicy blueberry leads, backed by ripe fruit and undercut with herbal tones and a touch of pine, and it was that fruity scent that filled the tent in the final weeks.
Granddaddy Purple Auto
|
Granddaddy Purple x Big Bud Auto |
|
13 to 16 oz/m² |
|
2 to 4 feet |
|
55 - 60 days |
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Up to 19% |
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Sativa 20%, Indica 75%, Ruderalis 5% |
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4 to 5 oz/plant |
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3 to 5 feet |
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Physically Relaxing, Sleepy, Uplifting |
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Low |
|
70 - 85 days after germination |
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