How to grow Grandmommy Purple
- Breeder: Herbies
- Genetics: Mostly Indica
- THC: up to 30%
- Type: Photoperiod, feminized seeds
- Difficulty: moderate
- Flowering: about 9 weeks
- Flavors: sweet, earthy, berry
Grandmommy Purple is an 80% Indica cross of Big Bud and Purple Urkle with 28-33% THC, delivering ecstatic happiness then deep sleepy relaxation, with sweet wild-berry flavors.
What is specific about Grandmommy Purple
- Very high THC, nutrient-hungry in flower; ramp feeding gradually and watch for tip burn.
Indoor calendar for Grandmommy Purple
| Stage | When | Note |
|---|---|---|
| Germination | week 1 | Warm, humid and dark until the sprout shows. |
| Seedling | weeks 2 to 3 | Gentle light on 18/6. |
| Vegetative | weeks 4 to 7 (you decide) | Three to six weeks on 18/6; longer growth means a bigger plant. |
| Flowering | 9 weeks after the switch to 12/12 | Expect the plant to stretch in the first two to three weeks. |
| Harvest | around week 16 to 18 | Depends on how long you let it grow first. |
| Dry and cure | three to four weeks more | One to two weeks drying, then at least two weeks curing in jars. |
About 19 to 22 weeks from seed to cured buds, with 9 weeks of flowering.
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 4–7 (you control length)
Build the plant.
- Photoperiod: keep 18/6 as long as you want size, then flip to 12/12 to begin flowering.
- Feed grow (high-N) nutrients; train (LST/topping) for an even canopy.
- Indica-leaning: bushier/compact, keep airflow between colas.
Flowering: ~9 weeks of bloom
Buds bulk up.
- Now on 12/12. Expect a 2–3 week stretch early, give headroom.
- 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.
~16–17 weeks (plus veg time).
Growing Grandmommy Purple outdoors
Outdoors in central Europe photoperiod plants start flowering in early to mid August, so Grandmommy Purple, with 9 weeks of flowering, is usually ready in early to mid October. That is late in the season: autumn rain and cold bring bud rot, so it suits a greenhouse, a dry southern spot or an indoor grow better than an open northern garden.
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 compares
At 9 weeks it takes longer than 52% of the 98 photoperiod strains in our guides (typical: 8.5 weeks), so plan the extra time.
Its THC, up to 30%, is above the typical 20% for these photoperiod strains.
Bred by Herbies, one of 50 Herbies strains with a grow guide here.
| Similar strain | Flowering | THC | Breeder |
|---|---|---|---|
| Master Kush | 8 weeks | 20% | Dutch Passion |
| Blueberry | 9 weeks | 20% | Dutch Passion |
| Skunk #1 | 9 weeks | 15% | Dutch Passion |
| Black Lebanon | 8 to 9 weeks | 15% | Dutch Passion |
Effects
sleep, relaxing
Grower verdict: 1 reviews, average 5/5.
Questions
Is Grandmommy Purple easy to grow?
Grandmommy Purple is considered moderate to grow. This read draws on 1 grower reviews.
When is Grandmommy Purple ready outdoors?
Outdoors in central Europe photoperiod plants start flowering in early to mid August, so Grandmommy Purple, with 9 weeks of flowering, is usually ready in early to mid October. That is late in the season: autumn rain and cold bring bud rot, so it suits a greenhouse, a dry southern spot or an indoor grow better than an open northern garden.
How strong is Grandmommy Purple?
The breeder lists up to 30% THC. Real results depend on light, feeding and harvest timing.
When should I switch Grandmommy Purple to 12/12?
When the plant is about half the final height you want: it can double in size during the first weeks of flowering. Flowering then takes about 9 weeks.
Grow Grandmommy Purple with me on Telegram: what to do each week, a weekly check in, photo diagnosis and harvest timing. Free, no account.
Track this grow week by week on WeedYouGrow, free, no login.
Something looks wrong? Find your plant problem.
Need the seeds? Find Grandmommy Purple seeds on SeedYouLike.