Français Granddaddy Purple is a mostly indica strain from Purple Urkel crossed with Big Bud, testing at 25% THC, with a berry and grape flavour and a heavy, relaxing body effect. It flowers in 65 to 70 days and finishes outdoors in October. Its reputation is for being easy to grow, which is unusual among purple strains, and that is the main reason it has stayed in catalogues for twenty years.
Granddaddy Purple at a glance
| Granddaddy Purple | |
| Genetics | Purple Urkel × Big Bud |
| Type | Mostly indica |
| THC | 25% |
| Flowering time | 65 to 70 days |
| Outdoor harvest | October |
| Yield | 450 to 500 g/m² indoors, 600 to 700 g per plant outdoors |
| Flavour | Berry, grape, fruity |
| Grow difficulty | Easy, indoor or outdoor |
| Seeds | Feminized |
A note on the numbers in this article: harvest dates, flowering times and yields are ranges, not promises. They vary depending on growing conditions: the grower, the method and the season's weather. "Mold resistant" means mold tolerant: less prone to mold and slower to be affected. No strain is 100% mold resistant. How we set these numbers →
What the genetics tell you
The two parents each contribute something you can see in the plant. Purple Urkel brings the colour and the grape note — it is the reason Granddaddy Purple goes purple rather than the reason it yields. Big Bud brings exactly what the name says: dense, heavy flowers and the structure to carry them.
That combination is why GDP is forgiving. A lot of deep-purple cultivars are temperamental and low-yielding, because the traits that produce anthocyanin pigment often come packaged with finicky genetics. Crossing into Big Bud gave this one commercial-scale flowers and a tolerant constitution, so the purple comes without the usual penalty.
Effects and flavour
The effect is a body effect. At 25% THC it is not a mild strain, and the indica weighting means it settles into the limbs rather than the head. Most people describe it as relaxing and heavy, which is why it is typically an evening strain rather than a daytime one. Plan accordingly if you are new to this potency band.
On flavour, berry and grape dominate, with a general sweetness underneath. The grape note is the signature and it carries through from the Purple Urkel side.
Growing Granddaddy Purple
Indoors
Sixty-five to seventy days of flowering puts GDP in the normal range rather than the fast one, so budget roughly ten weeks of bloom on top of your vegetative time. The Big Bud influence means the flowers get heavy, and heavy flowers on an indica frame want support: stake or net before you need to, because a branch that folds in week eight does not recover.
Density is also a humidity problem. Tight indica buds hold moisture in the core, which is where botrytis starts. Keep air moving through the canopy, strip the growth that will never see light, and bring relative humidity down through the last fortnight.
Outdoors
An October finish is late for a northern Canadian season. In the warmer pockets of southern Ontario, the Montréal area or the BC interior it will ripen in a normal year, but it is competing with the first hard frost and with autumn rain arriving on dense flowers. If your season is shorter than that, or you do not have a sheltered spot, pick a September finisher instead. We group our outdoor cannabis seeds by harvest month so you can filter rather than guess.
About the purple
Colour in cannabis is anthocyanin expression, and it is partly genetic and partly environmental. GDP carries the genetics; cool nights late in flower are what bring the colour out. Growers chasing the deepest purple usually let night temperatures drop in the final two or three weeks. Worth knowing that the colour is cosmetic — it tracks pigment, not potency.
Frequently asked questions
What is Granddaddy Purple?
A mostly indica cannabis strain created by crossing Purple Urkel with Big Bud. It is known for deep purple flowers, a berry and grape flavour, 25% THC and a heavy relaxing effect.
Is Granddaddy Purple indica or sativa?
Mostly indica. The effect is physical and relaxing rather than cerebral, which is why it is generally used in the evening.
How strong is Granddaddy Purple?
Our seeds produce plants testing around 25% THC. That is high, though not at the top of the modern range. The indica weighting makes it feel heavier than the number alone suggests.
What does Granddaddy Purple taste like?
Berry and grape, with a general sweetness. The grape note comes from the Purple Urkel parent and is the strain's signature.
What are the parents of Granddaddy Purple?
Purple Urkel and Big Bud. Purple Urkel contributes the colour and the grape flavour; Big Bud contributes the dense, heavy flowers.
How long does Granddaddy Purple take to flower?
Sixty-five to seventy days indoors. Outdoors it finishes in October.
Is Granddaddy Purple easy to grow?
Yes, which is the unusual part. Many deep-purple cultivars are temperamental, but the Big Bud cross gave this one a tolerant constitution. The one thing it does need is support for the weight of the flowers, and good airflow because they are dense.
Why is Granddaddy Purple purple?
Anthocyanin pigment, inherited from Purple Urkel and brought out by cool night temperatures late in flower. It is a cosmetic trait and does not indicate potency.
Is Granddaddy Purple good for sleep?
Many people use it that way, because the effect is physical and sedating rather than stimulating. We are not making a medical claim; if you are considering cannabis for a health reason, talk to a clinician.
Can you grow Granddaddy Purple outdoors in Canada?
In the warmer regions, yes, but an October finish leaves little margin against frost and autumn rain. In a shorter season choose a September-finishing strain. Note also that home cultivation is prohibited in Quebec, though legal in most other provinces.
Is Granddaddy Purple the same as Grandaddy Purp or GDP?
Yes. Grandaddy Purp, Granddaddy Purps and GDP all refer to the same strain; the spelling varies by seller.
Granddaddy Purple seeds from Quebec
Our Granddaddy Purple feminized seeds are $52 for a pack of 5, $95 for 10 and $185 for 20, and they are feminized, so every viable seed produces a flowering female and there are no males to identify and remove.
They ship from Quebec, usually the same day or within 24 hours of payment, Monday to Friday. Canada takes 3 to 7 days by standard post or 2 to 3 days by Express; the USA is 1 to 2 business days by Express, and shipping is free over $200. Every pack carries our 80% germination guarantee and a delivery guarantee, in plain unbranded packaging with no signature required.
If you want the purple colour with a shorter flowering time, we also carry Granddaddy Purple in an autoflowering version, which flowers on age rather than daylight and finishes in roughly ten to twelve weeks from seed.
