Grandaddy Purple Strain Autoflower SeedsThe grape-scented California purple in a compact autoflower
5.00 out of 5 · 11 reviewsThe Grandaddy Purple strain in autoflower form puts the grape-scented, deep purple indica that Ken Estes popularized in California into a compact plant that finishes about 8 to 11 weeks from seed. These feminized autoflower seeds grow female plants that bloom on their own, with no change in light schedule, and usually stay around 60–100 cm (2–3 ft) tall. Seed banks list THC at roughly 16–24%.
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What is the Grandaddy Purple strain?
Grandaddy Purple Auto is the autoflowering version of Granddaddy Purple (GDP), the grape-scented indica Ken Estes popularized in California around 2003, bred with ruderalis genetics so the plant blooms once it is old enough, whatever the light schedule. It needs roughly 8 to 11 weeks from sprouting to harvest, usually stays 60–100 cm tall and is listed at about 16–24% THC. Expect the familiar grape-berry aroma, a relaxing, heavy effect and, on many plants, purple-tinged buds.
Ratio from a GDP autoflower seed listing; AllBud gives the photoperiod GDP the same 70/30 split. The ruderalis share isn't published.
GDP is one of the best-known purple strains, and its auto version keeps the grape-candy smell in a plant small enough for a closet.
Grandaddy Purple strain specs
The autoflower figures below come from seed banks that sell GDP Auto, while the background facts (breeder, parents, effects) come from AllBud, Leafly and PAX's history of the photoperiod GDP. Auto lines differ between sellers, so each number is a reported range.
| Type | Indica-dominant autoflower, about 70% indica |
|---|---|
| Genetics | Granddaddy Purple (Purple Urkle × Big Bud) × ruderalis |
| Bred by | Original GDP: Ken Estes, California, around 2003; auto versions by several seed banks |
| THC | About 16–24% on auto listings; photoperiod GDP 20–27% on AllBud |
| CBD | Low; most listings under 1% |
| Main terpenes | Myrcene, caryophyllene, pinene, linalool |
| Aroma & flavor | Grape, berry, sweet, earthy, floral |
| Reported effects | Relaxed, euphoric, happy, sleepy, hungry |
| Seed type | Autoflower feminized (female plants) |
|---|---|
| Seed to harvest | 8–11 weeks (most listings say 8–10) |
| Outdoor harvest | Ready roughly 2–2.5 months after an outdoor sowing between late spring and midsummer |
| Height | 60–100 cm (2–3.3 ft) indoors; up to about 1.4 m (4.5 ft) outdoors |
| Yield | 200–400 g/m² (0.7–1.3 oz/ft²) indoors; 100–150 g (3.5–5 oz) per plant outdoors |
| Difficulty | Easy to moderate |
| Best methods | LST, Sea of Green, final pots from day one |
| Climate | Indoors, or temperate to warm gardens; several runs per season |
Where does the Grandaddy Purple strain come from?
Grandaddy Purple traces back to Ken Estes, a California grower who popularized it in the San Francisco Bay Area around 2003; strain databases such as AllBud and Leafly list it as Purple Urkle × Big Bud. Estes himself has told a different story, describing his original purple plant as a gift from Native American growers in Northern California and a daughter of a Skunk #1 backcross, so the exact pedigree is still debated. Either way, GDP became one of California's signature purple indicas.
The autoflower version is a seed-bank creation rather than Estes's own work: breeders crossed GDP with ruderalis, a hardy cannabis type that blooms based on age rather than daylight hours, then selected for purple, grape-scented plants. Sellers don't all use the same recipe. One lists Purple Urkle × Big Bud × ruderalis, another adds Hindu Kush, and a third uses a different auto partner, so plants can vary a little between brands.
Why does Grandaddy Purple turn purple?
Grandaddy Purple turns purple because its genetics produce anthocyanins, the same pigments that color grapes and blueberries, in its leaves and calyxes. The trait comes from its purple ancestry, which most databases trace to Purple Urkle, and cooler nights late in bloom tend to deepen it. In autoflower versions the color can vary more from plant to plant, since each seed bank used a different auto partner.
Color isn't potency. A deep purple GDP Auto is not necessarily stronger than a green one; judge ripeness by the trichomes, not by leaf or bud color.
What does Grandaddy Purple taste like, and how does it feel?
Aroma and flavor
Grandaddy Purple tastes like sweet grape and mixed berries over an earthy, herbal base, with a slightly sharp, pungent finish. Some auto lines add a floral, violet-like note.
- Grape
- Berry
- Sweet
- Earthy
- Floral
- Herbal
Terpenes
- Myrcene
- Musky ripe fruit; PAX calls it GDP's leading terpene
- Caryophyllene
- Peppery warmth
- Pinene
- Fresh pine edge
- Linalool
- Soft, lavender-like floral note
Terpene ratios vary between GDP autoflower lines and with growing conditions.
Reported effects
Grandaddy Purple is best known for calm, heavy relaxation that starts with a happy, euphoric lift and often ends in sleepiness. AllBud and seed-bank listings describe euphoria, hunger and deep body relaxation, which is why most people save GDP for the evening.
- Relaxed
- Euphoric
- Happy
- Sleepy
- Hungry
Grandaddy Purple's commonly reported downsides are cottonmouth, dry eyes and, for some people, dizziness or grogginess after a heavy session.
These Grandaddy Purple effect notes summarize AllBud and Leafly user reports and seed-bank descriptions. Responses vary between people, and no part of this is medical advice.
How do you grow Grandaddy Purple seeds?
Grandaddy Purple autoflower seeds are easy to grow if you respect the clock: sow them straight into their final pots, keep a long-day schedule (18/6 or 20/4) the whole time, bend branches rather than topping late, and pick the buds roughly 8 to 11 weeks after sprouting.
- GerminateDays 1–7
Sow each GDP Auto seed directly in its final container, around 11–20 L (3–5 gal), because autoflowers lose time recovering from transplants.
- Early growthWeeks 2–4
Keep the lights on 18–20 hours a day and start low-stress training early; the vegetative window is short, only a few weeks, before buds start forming unprompted.
- FlowerWeeks 4–9
Pistils appear without any change to the light schedule. Cooler nights in the last weeks can deepen the purple color.
- HarvestWeeks 8–11 from seed
Pick when the trichome heads look mostly milky with a scattering of amber, usually 8 to 11 weeks after germination.
Grow tips for Grandaddy Purple
- Skip transplanting. A GDP Auto lives only about 2 to 2.5 months, so plant it where it will finish and avoid disturbing the roots.
- Bend, don't cut. Low-stress training spreads the short frame and opens the center; heavy topping or defoliation late in early growth can stunt an autoflower.
- Keep the lights long. Grandaddy Purple Auto doesn't need 12/12 to flower; most growers run 18/6 or 20/4 from seed to harvest.
- Feed lightly. Seed listings rate GDP Auto as a moderate feeder, so start nutrients at about half strength and raise them only if the lower leaves pale.
- Use cool nights for color. A night drop of around 5 °C (9 °F) late in bloom can bring out stronger purple, but keep nights above about 15 °C (59 °F).
- Plan several outdoor runs. Because Grandaddy Purple Auto finishes in under three months from seed, you can sow it outdoors from late spring and fit more than one harvest into a warm season.
Is Grandaddy Purple the right strain for you?
Great pick if you
- Want a short, fast plant for a small tent, closet or balcony
- Love grape and berry flavors and purple buds
- Prefer a relaxing evening strain
- Want a harvest roughly 2 to 2.5 months after sowing
- Are a beginner looking for a forgiving first auto
Think twice if you
- Want big yields from a long vegetative phase
- Hope to take cuttings, since auto clones start flowering almost at once
- Prefer an energetic daytime high
- Want the higher THC reported for top photoperiod GDP
Grandaddy Purple strain FAQ
Is Grandaddy Purple indica or sativa?
Grandaddy Purple is an indica-dominant strain. AllBud lists the photoperiod GDP at 70% indica and 30% sativa, and autoflower listings use the same 70/30 split, with ruderalis genetics added so the plant flowers automatically.
Is it Grandaddy Purple or Granddaddy Purple?
Both spellings refer to the same strain. Most strain databases write Granddaddy Purple with a double d, and it is also called GDP, Grand Daddy Purple or Granddaddy Purps. Grandaddy Purple is a common shop spelling of the same name.
How fast does Grandaddy Purple Auto finish?
Most autoflower listings give 8 to 10 weeks from germination to harvest, and some allow up to 11 weeks. Flowering starts on its own after a few weeks of growth, with no change to the light schedule.
How much THC does Grandaddy Purple Auto have?
Seed banks list Grandaddy Purple Auto at roughly 16–24% THC, with low CBD. AllBud rates the photoperiod GDP a little higher, at 20–27%. Results depend on the seed line, light intensity and harvest timing.
How tall does Grandaddy Purple Auto grow?
GDP autoflowers usually reach 60–100 cm (2–3.3 ft) indoors. Outdoors in full sun some plants grow to about 1.4 m (4.5 ft), which still keeps them manageable on a balcony or in a small greenhouse.
How much does Grandaddy Purple Auto yield?
Seed listings give 200–400 g/m² (0.7–1.3 oz/ft²) indoors and about 100–150 g (3.5–5 oz) per plant outdoors. That is less than photoperiod GDP, which trades a longer grow for bigger plants.
Who created Grandaddy Purple?
Ken Estes is credited with popularizing Granddaddy Purple in California's Bay Area around 2003. Strain databases list it as Purple Urkle × Big Bud, though Estes has described a different origin. The autoflower versions came later, from seed banks crossing GDP with ruderalis.
Do Grandaddy Purple Auto buds turn purple?
Many do. GDP carries strong purple genetics, and cool nights late in flowering often deepen the color. Because each seed bank's auto line is different, some plants stay mostly green with only purple tips.
How is Grandaddy Purple Auto different from photoperiod GDP?
Photoperiod Granddaddy Purple needs long nights (a 12/12 schedule) to bloom and is usually vegged for several weeks first, so it grows bigger and yields more. The autoflower blooms on its own and completes its whole life in about 8 to 11 weeks on a smaller plant.
Grandaddy Purple reviews
5.00 out of 5 from 11 reviews
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11 reviews for Grandaddy Purple Strain Autoflowering Feminized Marijuana Seeds
Grandaddy Purple's relatives and similar strains
Granddaddy Purple Feminized
Purple Urkle Feminized
Big Bud Feminized
Purple Kush Autoflowering FeminizedBeaver Seeds sells cannabis seeds for collection and genetic preservation where permitted. Check the laws in your state, province or country before germinating seeds. Effects are user-reported and are not medical claims.
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Bella –
classic purple calm with deep body melt. easy autoflower option. nighttime go-to.