Key Lime Pie Strain History: From Clone-Only Cut to Sin City Seeds’ Lime Genetics Dynasty

One GSC phenotype with an unmistakable lime terpene profile became the foundation for the most complete single-strain breeding program in cannabis. This is the full Key Lime Pie story.

Most cannabis strains exist as a single variety. A breeder creates a cross, names it, releases it, and moves on. Key Lime Pie is different. What started as one exceptional phenotype of Girl Scout Cookies turned into an entire genetics dynasty, with Sin City Seeds building a complete lime family tree from a single mother plant.

There are now 8+ distinct varieties tracing their lineage directly to the original KLP cut. No other phenotype in cannabis has been explored this thoroughly through breeding. The lime line includes selfed reproductions, double backcrosses, and crosses with everything from Blue Power to Zkittlez to Purple Urkle, all anchored by that unmistakable lime terpene signature.

This is the full story: where Key Lime Pie came from, what makes its genetics special, and a complete guide to every lime variety Sin City Seeds created from it.

Where Did Key Lime Pie Come From?

Key Lime Pie emerged as a phenotype of Girl Scout Cookies during the early 2010s GSC boom. GSC itself was one of the most significant strains of the decade, a cross typically attributed to the combination of OG Kush and Durban Poison (with some lineages including Cherry Pie influence). As GSC packs circulated among growers, certain phenotypes stood out for particular characteristics. The Forum Cut became the gold standard for cookie flavor. The Thin Mint phenotype was prized for its potency. And Key Lime Pie became famous for something entirely different: a sharp, bright lime-citrus terpene profile that didn’t smell like cookies at all.

The KLP phenotype was selected by a grower who recognized that this particular plant’s terpene expression was unique within the GSC family. Where other GSC phenotypes leaned toward sweet, doughy, earthy aromas, KLP hit you with lime zest the second you cracked a jar. It was immediately identifiable and immediately popular.

Like many elite phenotypes of the era, KLP existed as a clone-only cut. You couldn’t buy seeds that would reliably produce the Key Lime Pie terpene profile. You had to know someone who had the clone, and those clone networks were limited and regional. This exclusivity drove demand and created the conditions for someone to eventually capture those genetics in reproducible seed form.

That someone was Sin City Seeds.

What Are Key Lime Pie’s Genetics?

Key Lime Pie carries GSC genetics, meaning its foundation is OG Kush crossed with Durban Poison. The specific phenotype expression that produces the lime terpene profile is driven by an elevated ratio of limonene and terpinolene relative to other GSC phenotypes. These terpenes combine to create the sharp citrus aroma that makes KLP immediately distinguishable from its cookie siblings.

Terpene Profile

The limonene dominance is what sets KLP apart. Most GSC phenotypes show myrcene or caryophyllene as the primary terpene. KLP flips the script with limonene at the top of the profile, creating that bright citrus punch that no other cookie phenotype delivers. The terpinolene contributes an herbal complexity that prevents the lime from reading as one-dimensional, while the caryophyllene provides the peppery warmth that grounds the experience.

The effects match the terpene profile. KLP produces a euphoric, uplifting onset that gradually settles into full-body relaxation. It’s creative and social in the early phase, then progressively sedative as the high develops. THC levels in properly grown KLP run 20-25%, placing it firmly in the potent category without being overwhelming.

How Did Sin City Build a Lime Dynasty?

Most breeders would have stopped at making an S1 of Key Lime Pie and calling it a day. Sin City Seeds took a fundamentally different approach. They recognized that the KLP terpene profile was so distinctive and so commercially desirable that it deserved to be explored through every breeding technique available.

The program started with the Key Lime Pie S1, a straightforward selfed reproduction of the original clone. This gave growers their first opportunity to access KLP genetics in seed form. But S1 production was just the beginning.

Sin City then created Key Lime BX2, a double backcross to the original KLP mother. Where S1 seeds can show some variation as recessive traits express, a BX2 concentrates approximately 87.5% of the parent genetics, producing offspring that express the lime profile more consistently. For growers who want the closest possible approximation of the original clone in seed form, Key Lime BX2 is the answer. (If the terminology here is unfamiliar, our seed terminology guide explains S1 and BX designations in plain language.)

From there, the program expanded into crosses that combined KLP’s lime terpenes with other desirable genetic contributions. Each cross was designed to answer a specific question: what happens when you pair lime with berry? With cream? With tropical fruit? With grape?

The result is the most thorough single-phenotype breeding program in the industry. Eight distinct varieties, each carrying the KLP lime signature but expressing it through a different genetic lens. No other strain has been worked this comprehensively by a single breeder.

What Do Each of the Lime Varieties Offer?

Each lime cross combines KLP’s citrus terpenes with a different genetic partner, creating distinct flavor profiles and effects while maintaining the lime foundation. Here’s what separates them.

Key Lime Pie S1 is the purest representation of the original clone. Every seed carries only KLP genetics, and most plants will closely resemble the mother. This is where to start if you want to experience the original Key Lime Pie terpene profile exactly as it was selected. Expect sharp lime zest, pie crust sweetness, and the classic KLP effect progression from euphoria to relaxation.

Key Lime BX2 is the more refined version. Two generations of backcrossing have locked in the lime expression more tightly than the S1, reducing the variation across a pack. If consistency is your priority and you want every plant to scream lime, BX2 is the pick.

Blue Lime Pie crosses KLP with Sin City’s signature Blue Power male (The White x Blue Moonshine). The result adds Blue Power’s berry undertones and exceptional frost production to the lime base. Think lime sherbet with a blueberry swirl. The Blue Power influence also contributes heavy trichome coverage and a more indica-leaning body effect.

Deep Space Lime pushes the lime profile into heavier territory. This cross produces deeply relaxing effects while maintaining the citrus terpene character. Dense bud structure, heavy resin production, and a lime flavor that gets richer and more complex during the cure.

Key Lime Kahlua introduces coffee and cream notes to the lime base. The name is accurate: this variety genuinely smells like a lime-coffee cocktail. It’s one of the more unique terpene combinations in the catalog and demonstrates how lime terpenes can complement unexpected flavor partners.

Z Lime Pie combines KLP with Zkittlez genetics, blending lime citrus with the candy-fruit sweetness that made Zkittlez a cultural phenomenon. The tropical influence softens the sharp lime edge into something more like a lime candy or citrus gummy. Effects lean balanced, with creative onset and gentle physical relaxation.

Lime Urkle pairs KLP with Purple Urkle, creating a lime-grape fusion that doesn’t exist anywhere else in cannabis. Purple Urkle contributes grape candy terpenes, purple coloration, and indica-dominant effects. The lime and grape combination produces an unusual but genuinely compelling flavor profile.

Blue Lime Runtz is a second-generation lime cross, combining Blue Lime Pie with Runtz genetics. This layering approach takes the lime-berry profile from Blue Lime Pie and adds Runtz’s candy creaminess and bag appeal. It’s the most complex entry in the lime line, carrying influence from KLP, Blue Power, and Runtz in a single variety.

The Complete Lime Family Tree

Two additional Sin City varieties carry KLP influence without being strictly part of the lime line. Pie After Dark and Honey Peach Pie both use KLP or its derivatives as parent genetics, pushing the lime influence into new combinations with dessert and stone fruit terpene partners.

How Should You Grow Key Lime Pie Seeds?

KLP genetics grow like typical GSC varieties: medium-height plants with dense branching and heavy resin production. They respond well to topping and LST (low-stress training) to open up the canopy and improve light penetration to lower bud sites.

Flowering time sits in the 56-63 day range (8-9 weeks), which is manageable for most indoor growers. The plants tend to stack weight in the final two weeks, so resist the urge to harvest early. The lime terpene profile also develops and intensifies during the last 10-14 days of flower, so patience is rewarded with stronger aroma and flavor.

One growing note specific to KLP genetics: the lime terpene expression is sensitive to dry and cure conditions. A slow dry (60°F, 60% humidity, 10-14 days) followed by a minimum 2-week jar cure will preserve and develop the lime zest aroma. Rushed drying or hot temperatures will degrade the terpinolene and limonene that define the KLP profile, leaving you with a less distinct final product.

Humidity management during flower is also important. The dense bud structure inherited from the GSC lineage can trap moisture, creating conditions for bud rot if humidity runs too high in the late flowering period. Keep flower-room humidity below 50% in the final three weeks and maintain good airflow through the canopy.

For the complete story on Sin City Seeds and their broader catalog beyond the lime line, read our Sin City Seeds breeder profile. And browse the full Dark Coast Seed Co. catalog for additional lime varieties and Sin City releases.