How to grow Grandmommy Purple Auto
- Breeder: Herbies
- Genetics: Mostly Indica
- THC: up to 25%
- Type: Autoflower
- Difficulty: moderate
- Seed to harvest: about 9 to 10 weeks
- Flavors: sweet, berry
Grandmommy Purple Auto by Herbies Seeds is a 75% Indica autoflower with 25% THC and sweet berry flavors, delivering deeply relaxing, sleepy effects ideal for evening or medical use.
What is specific about Grandmommy Purple Auto
- Autoflower, avoid transplanting and heavy training; it can't recover lost veg time, so stress sets it back.
Indoor calendar for Grandmommy Purple Auto
| Stage | When | Note |
|---|---|---|
| Germination | week 1 | Seed in its final pot; autoflowers dislike transplanting. |
| Seedling and growth | weeks 2 to 4 | Light on 18 hours a day for the whole grow; no switch to 12/12 needed. |
| Flowering | from about week 4 to week 10 | Flowering starts by age, not by light. |
| Harvest | week 9 to 10 | Judge by trichomes, not the calendar. |
| Dry and cure | weeks 10 to 14 | One to two weeks drying, then at least two weeks curing in jars. |
About 12 to 14 weeks from seed to cured buds.
Week by week
Germination: Days 1–7
Pop the seed.
- Soak in a moist paper towel or plant 1cm deep in light, airy soil.
- Keep warm (22–25°C), humid and dark until the sprout appears.
- Moist, never soggy.
Seedling: Weeks 2–3
First true leaves.
- Gentle light on 18/6, high humidity (~65%).
- Tiny waterings near the stem; let the top dry between.
- Quarter-strength nutrients at most.
Vegetative: Weeks 4–6 (auto)
Build the plant.
- Autoflowers veg briefly then flower on their own, start in the final pot, don't transplant late.
- Feed grow (high-N) nutrients; train (LST/topping) for an even canopy.
- Indica-leaning: bushier/compact, keep airflow between colas.
Flowering: ~5–6 weeks of bloom
Buds bulk up.
- Stays on 18/6 to harvest.
- Switch to bloom (high-P/K) nutrients; lower humidity (~45%) to prevent bud rot.
- Watch trichomes: mostly cloudy with some amber = peak ripeness.
Flush & harvest: Final 1–2 weeks
Finish clean.
- Plain water (no nutrients) the last 1–2 weeks for a smoother smoke.
- Harvest, wet-trim, dry slowly (~60°F / 60% RH, 7–14 days).
- Cure in jars 2+ weeks, burping daily at first.
~9–10 weeks seed to harvest.
Growing Grandmommy Purple Auto outdoors
Sown outdoors in mid May, after the last frost, Grandmommy Purple Auto should be ready in mid to late July. That leaves time for a second run: a seed sown by early July finishes around early to mid September.
Drying and curing
Its sweet and berry notes come from the most volatile terpenes, the first to go in a warm, fast dry. Dry slowly around 18 °C and 60% humidity for 10 to 14 days and cure in jars to keep them.
How Grandmommy Purple Auto compares
At 9 to 10 weeks it finishes faster than 72% of the 72 autoflowers in our guides (typical: 10.5 weeks).
Its THC, up to 25%, is above the typical 20% for these autoflowers.
Bred by Herbies, one of 50 Herbies strains with a grow guide here.
| Similar strain | Seed to harvest | THC | Breeder |
|---|---|---|---|
| Keepers OG Autoflower | 8 to 10 weeks | 32% | Herbies |
| Lemon Jack Autoflower | 9 weeks | 19% | Herbies |
| Auto Ultimate | 10 to 11 weeks | 25% | Herbies |
| Auto Blueberry | 8 to 10 weeks | 15% | Dutch Passion |
Effects
relaxing, euphoric, focus
Grower verdict: 3 reviews, average 5/5.
Questions
Is Grandmommy Purple Auto easy to grow?
Grandmommy Purple Auto is considered moderate to grow and flowers automatically without a light schedule change. This read draws on 3 grower reviews.
When is Grandmommy Purple Auto ready outdoors?
Sown outdoors in mid May, after the last frost, Grandmommy Purple Auto should be ready in mid to late July. That leaves time for a second run: a seed sown by early July finishes around early to mid September.
How strong is Grandmommy Purple Auto?
The breeder lists up to 25% THC. Real results depend on light, feeding and harvest timing.
Does Grandmommy Purple Auto need a light change to flower?
No. Grandmommy Purple Auto is an autoflower: it flowers by age and goes from seed to harvest in about 9 to 10 weeks on 18 hours of light a day.
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