Flowering
She’s making the buds now. Your job is to hold your nerve.
Flowering is where everything you’ve done pays off — or doesn’t. The plant knows how to do this. Set the stage, read her signals, and resist the urge to “do something”.
What good looks like
Week by week, flip to ripe
- Day 0
The flip
You switch to 12/12 and start the clock. Measure first — she will double, sometimes triple, in height. Flip at 30–40cm in a 1.6m tent so the stretch has headroom.
- Wk 1–3
The stretch
She rockets up — up to an inch a day. This is exactly right. Hands off: no topping, no defoliating. Bridge the feed gently toward potassium.
- Wk 2–4
First pistils
White hairs at the nodes — she has committed to flower. Feed shifts fully to bloom: phosphorus and potassium up, nitrogen down. Start at half strength.
- Wk 4–6
The swell
Buds stack, trichomes frost over, the tent starts to reek (carbon-filter time). EC 1.8–2.0, humidity down to 45%, air always moving.
- Wk 6–8
Home stretch
Lower leaves yellow and drop — that is her finishing, not failing. Feed tapers right back, humidity to 40%, an optional gentle flush.
- Ripe
She tells you
70–90% cloudy trichomes with 10–20% amber, under a loupe. The calendar lies. The trichomes do not.
Revision flashcards · tap to reveal
Six you actually need — can you remember?
Before you start
What you'll need
Tick off what you've already got. Whatever's left, the kit just below has you sorted — skip anything you don't need.
Get your gear
Your Flowering kit
The bits that carry her through the stretch and into fat colas — affiliate links, no extra cost, keeps the lights on here.— Dave
Swipe right to add · left to skip · or use the buttons
Watch for
Catch these early
The early sign, what it means, and the fix. The full stories are in the book.
A leaf inside a cola has gone yellow or brown for no clear reason
Bud rot (botrytis), working from the inside out where the air can’t reach.
Fix: Humidity under 50%, keep air moving, run a dehumidifier. Cut out affected buds and sterilise between cuts.
📖 Dave lost his four biggest colas to this on grow three. The full story →
The tent zip — or an indicator LED — glows during lights-off
A broken dark period can turn her hermaphrodite: pollen sacs, then seeds instead of resin.
Fix: Sit in the tent with the lights off and tape every pinprick. Even the green LED on the power strip.
📖 A two-second flash from a phone can seed the whole tent. The full story →
She is kissing the light and you have reached for the scissors
Topping or heavy defoliation in week one stalls her for a fortnight — energy goes to healing, not buds.
Fix: Leave her be. Tuck a leaf, bend a branch, but no surgery during the stretch.
📖 Dave topped his in week one and pulled 19g off a plant that should have given three times that. The full story →
The seed bank said 8 weeks, the hairs are orange, and you’re itching to chop
Harvesting by the calendar usually means a week or two early — thin, racy, underwhelming smoke.
Fix: Check trichomes at several bud sites under magnification. Cloudy for energy, a little amber for balance.
📖 The Rusher always regrets it. The full story →
Questions
Flowering FAQ
When do I flip to 12/12?
When she’s about 30–40cm in a standard 1.6m tent. Measure the tent, subtract pot height, your light’s hanging distance, and ~40cm of clearance — what’s left is your max height at flip. She’ll double in the stretch, so flip earlier than feels comfortable.
How much will she actually stretch?
Most plants double in height over the first two to three weeks; sativa-heavy genetics can triple. It’s not optional and it’s not a problem — it’s her building the scaffolding the buds form on. Plan headroom rather than fighting it.
My lower leaves are yellowing in late flower — what’s wrong?
Probably nothing. In the last couple of weeks she pulls mobile nutrients out of the old leaves to fuel the final push. That’s an annual plant finishing on purpose — not a deficiency. Don’t reach for more nitrogen.
Do I need to flush before harvest?
The science is genuinely debated. What’s not debated is that overfed plants taste harsh. For a first grow a gentle final-week flush (plain pH’d water) is a safe play — but proper feeding throughout matters more than any flush.
When exactly do I harvest?
When 70–90% of the trichomes on the buds (not the leaves) are cloudy/milky, with maybe 10–20% turned amber, viewed under a loupe or scope. Cloudy is energetic, amber is sedating. Ignore the seed bank’s week estimate.
Revision · quiz
Can you remember the flowering numbers?
Five quick ones, straight from the flashcards above. Instant feedback, retry till it sticks — no marks, no pressure.
1. What light schedule triggers the flip into flower?
Twelve hours of unbroken dark tells her summer is over and it is time to make buds, so 12/12 on a timer starts the clock.
2. Roughly how much taller does she get during the stretch?
Most plants double in the first two to three weeks, so flip earlier than feels comfortable rather than fighting the stretch.
3. True or false: cutting heavy lower leaves during the stretch in week one keeps the plant tidy and boosts your yield.
Heavy defoliation in week one stalls her for a fortnight while she heals instead of building bud — Dave once pulled just 19g off a plant that should have given three times that.
4. What feed EC are you aiming for during the swell in mid-flower?
EC 1.8 to 2.0 leaning on P and K feeds the bud stack without tipping into burn, the last thing you want once the colas are fattening.
5. Reading trichomes under a loupe, what is the harvest window?
Cloudy is potent and a little amber is balance — the trichomes tell the truth where the seed bank calendar lies.
Go deeper
The lessons for this stage
You've kept a plant alive and vegged one without helping it to death. Now comes the part where the money is made or lost: the flip.
9 min read Flower Feeding and the TaperHere's the thing most beginners get backwards: flowering is not the time to feed harder. It's the time to feed differently, and then feed less.
8 min read Humidity in Flower: The Bud-Rot WindowThe Sleepwalker did everything else right. Light dialled. Nutrients dialled. Temperature dialled. Never checked humidity once.
7 min read 12/12 Isn't the Only Way to FlowerTwelve hours on, twelve hours off. That's what you learn on day one. Cannabis needs twelve hours of darkness to flower. Don't mess with it. It's the rule.
4 min readThe whole story is in the book
The mistakes here are Dave’s, told properly — the panic, the scissors, the 19-gram harvest, the four lost colas. The web gives you the lesson; Grow Good Bud keeps the scars.
The web gives you the lesson; Grow Good Bud keeps the scars. The kit to grow it is at Dublin Indoor Gardening.