G13 Strain — Effects, Genetics, Grow Guide & Where to Buy
G13 is one of the most-searched cannabis strains in the United States, but the data behind the hype is what holds growers' attention. It is a indica-dominant (85% indica / 15% sativa) testing at roughly 20-24% THC, with a flowering window of 8-10 weeks under a 12/12 photoperiod. This guide pulls together the lineage, the effects, the grow data, and the practical answer to "where can I buy G13 seeds in the USA" in one place.
G13 Quick Stats
THC
20-24%
Indica
85%
Sativa
15%
Autoflower
No
Flowering
8-10 weeks
Difficulty
intermediate
Indoor Yield
450-550 g/m²
Outdoor Yield
500-700 g/plant
Plant Height
120-180 cm
G13 Effects & Experience
G13 is best known for relaxed, euphoric, sleepy. The effects come on within the first 10 minutes and settle into a stable plateau that lasts 90 minutes to two hours at typical doses. Growers and users consistently note that the high stays true to its profile rather than drifting — what you feel in the first 20 minutes is what you have for the next 90.
Growing G13
Growing G13 fits indoor growers in compact spaces; indica genetics stay short and bushy without aggressive training. G13 is photoperiod, which means you control when it flowers by switching from 18/6 (vegetative) to 12/12 (flowering). Most indoor growers veg for 4-6 weeks before the flip. Indoor yields land around 450-550 g/m² under quality LED, and outdoor plants given full sun and 5-7 gallon containers reliably produce 500-700 g/plant. Expected plant height is 120-180 cm, with intermediate cultivation difficulty. Practical tips that move the needle: maintain canopy airflow with an oscillating fan moving air through the leaves, not just above them, to prevent powdery mildew; and apply low-stress training in week 2 of veg — bend the main stem horizontally and tie down to expose lower nodes. The most common challenge growers report is calcium and magnesium supplementation under bright LED lighting; cal-mag at 2-3 mL/gal from week 2 prevents the most common deficiency.
G13 Lineage & Genetics
G13 is a Royal King Genetics in-house cross. The parental selection was chosen for compact stature and resin density, then stabilized over multiple generations to lock in phenotype expression. Seeds run true to the description on this page rather than spreading across a wide range of expressions.
Where to Buy G13 Seeds in the USA
G13 seeds ship from Royal King Seeds to all 50 US states with discreet packaging and a 95% germination guarantee. Average delivery is 3-5 business days, with the fastest routes typically reaching Alaska, Arizona, Arkansas, California, Colorado.
G13 FAQ
Is G13 indica or sativa?+
G13 is a indica-dominant with a 85% indica / 15% sativa split. The effects lean toward physical relaxation and a calm, settled headspace.
How long does G13 take to flower?+
G13 flowers in 8-10 weeks once you flip to 12/12 light cycle. Outdoor harvest typically lands in late September to mid-October across most US zones.
What is the THC content of G13?+
G13 tests at approximately 20-24% THC when grown to its potential. Real-world numbers depend on grow conditions, harvest timing, and curing — well-grown phenotypes can land at the high end of that range, while poorly cured flower tests lower.
Is G13 good for beginner growers?+
G13 is rated intermediate difficulty. Photoperiod genetics give you control over plant size and harvest timing, which means a bit more responsibility for getting the schedule right. Most growers with one harvest behind them handle this strain without difficulty.
Where can I buy G13 seeds in the USA?+
Royal King Seeds ships G13 seeds to all 50 US states with discreet packaging, 3-5 day delivery, and a 95% germination guarantee. The product page is at https://royalkingseeds.us/g13-feminized — checkout accepts standard cards, Apple Pay, and crypto.