Girl Scout Cookies, usually shortened to GSC, flowers for about 9 to 10 weeks indoors and finishes outdoors between late September and mid October in most US climates. Indoor growers commonly pull 300 to 500 grams per square meter, while a well-tended outdoor plant can produce 400 to 600 grams. Those numbers move up or down based on light intensity, root space, and how you handle the stretch that hits during the first three weeks of flower.
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GSC Quick Facts
- Indoor flowering time: 9 to 10 weeks, with some fast phenotypes finishing near 8 weeks
- Outdoor harvest: late September to mid October
- Indoor yield: roughly 300 to 500 g/m² in a dialed tent
- Outdoor yield: roughly 400 to 600 g per plant in good ground or large pots
- THC: commonly listed between 18 and 25 percent
- Stretch: moderate to strong, often doubling in height after the flip
How Long Does GSC Flower?
GSC is a slightly longer-flowering plant than the average hybrid. Most growers count the flowering clock from the day the light schedule changes to 12/12, not from the day pistils first show. From that flip, plan on 63 to 70 days.
girl scout cookies strain review
Indoor Flowering Time
Expect a first harvest window at day 60 and a full finish around day 70. The buds swell in the final two weeks, so cutting at day 55 usually costs you weight and density. A cheap loupe on the trichomes is a better guide than the calendar: cloudy heads with a few amber is the usual cue.
girl scout cookies strain review
Outdoor Flowering and Harvest Window
Outdoor plants start flowering when daylight drops below roughly 14 hours. In most of the US that puts the finish in late September for northern gardens and early to mid October further south. Cold, wet October weather is the main risk, so a greenhouse or a light dep setup helps protect the last two weeks.
GSC Yield Expectations
GSC is a quality-first strain, not a bulk producer. Breeder listings and grower reports generally place it in the medium range, and yield is one of the main reasons people run it in a dialed environment rather than a casual closet.
Indoor Yield
In a 4x4 tent with good airflow and a strong LED or HID, plan on 300 to 500 grams per square meter. Training matters here. GSC responds well to topping once or twice and a low stress training spread that keeps the canopy even, which is how you turn a handful of tall colas into a full screen.
Outdoor Yield
Outdoor plants that get six or more hours of direct sun, a large root zone, and a long vegetative run can reach 400 to 600 grams each. Plants left in small pots often stall in early flower and finish closer to 100 to 200 grams regardless of how healthy they look.
What Affects GSC Yield
- Light: canopy-level intensity is the single biggest lever on final weight
- Root space: outdoor plants need volume, indoor plants need a pot that dries in two to three days
- Temperature: GSC colors up in cool nights but slows down below about 65°F
- Humidity: dense buds and high humidity invite mold, which can wipe out a top cola overnight
- Nutrition: steady feed through mid flower, then a taper during the final flush
- Phenotype: seed runs vary, so clones from a keeper mother give consistent results
Seed to Harvest Timeline
- Germination: 1 to 3 days
- Seedling: week 1 to 2
- Vegetative: 4 to 8 weeks depending on your space and training plan
- Flower: 9 to 10 weeks
- Dry and cure: 10 to 14 days drying, then 2 to 4 weeks curing
A typical indoor run lands around 16 to 20 weeks total, and outdoor runs follow the season instead of a clock.
Tips for a Heavier GSC Harvest
- Top once at the fifth or sixth node, then train the branches outward for an even canopy.
- Defoliate lightly at day 21 and day 42 of flower to open bud sites to light.
- Keep night temps in the mid 60s late in flower for color without stalling growth.
- Support colas with stakes or a trellis around week 6, before the weight arrives.
- Hold the harvest until most trichomes are cloudy, since early cuts lose density.
Common Mistakes
The two most frequent problems are flipping too late and harvesting too early. GSC doubles in height after the light change, so a plant that already fills the tent will run out of headroom. And because the buds look impressive at week 7, many growers chop before the final swell and end up with airy flower that weighs far less than it should.
FAQ
Is 8 weeks enough for GSC?
Some fast phenotypes are close at day 56, but most plants are still filling out. Check trichomes rather than the label.
Does GSC yield more outdoors?
Per plant, usually yes, because the root zone and light are larger. Per square foot of garden, indoor and outdoor results end up in a similar range.
Is GSC hard to grow?
It is a moderate plant. It tolerates training well but rewards attention to humidity and airflow because the buds get dense.