Harvest Window Planner
The single highest-impact decision in your grow. Chop too early and you lose 30% of potency and yield; chop too late and THC degrades to CBN. Enter your flower week, check trichomes with a loupe, pick the effect chemistry you want — get a clear readiness verdict, calendar-date window, and full harvest prep checklist.
Check your harvest readiness
From the seed description. Most strains 7–10 weeks.
Optional but recommended — provides calendar-date window, not just "X days from now."
Auto-calculated from flip date. Override if needed.
Check with a jeweler's loupe or 60x USB scope. Percentages should sum to 100.
Sum: 0 / 100
Percentage of pistils that have browned and curled. Less reliable than trichomes.
About your strain type
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Pick a strain type to see guidance.
Common harvest mistakes
- Chopping based on time alone. "Week 8 = harvest" is a myth — genetics vary by 2+ weeks between phenotypes of the same strain. Always confirm with trichomes before the chop.
- Checking trichomes on sugar leaves. Sugar leaf trichomes mature faster and aren't representative. Check bud sites (not trim leaves) with your loupe.
- Harvesting on the lights-on cycle. Terpenes are highest just before lights-on. Chop at the end of the dark cycle, not mid-light.
- Skipping the cure. Drying is done when stems snap, but the flavor and smoothness come from curing — 2 weeks minimum in sealed jars, 4–6 weeks produces noticeably better flower.
Readiness verdict
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Fill out the inputs at left to see a verdict.
Flowering timeline
Assessment confidence
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Harvest prep checklist — open when 10 days out click to expand
Pre-harvest timing
| Stop nutrients | — |
| Start flush (soil/coco) | — |
| Dark period before chop | — |
Drying environment
| Temperature | — |
| Humidity | — |
| Drying duration | — |
Step-by-step
The four-step harvest readiness check
Enter your flower timeline
Pick your strain type (indica, hybrid, sativa, auto) and the breeder-stated flower weeks from your seed description. If you know the date you flipped to 12/12 (or the date your autoflower sprouted), add it — the tool auto-calculates your current flower week and gives you calendar-date harvest windows instead of just "X days from now." The "Set to today" button is for growers currently flipping. If you don't have a flip date, enter the current flower week manually.
Pick your effect preference
Different harvest timing produces different chemistry. Energetic / daytime — chop at peak cloudy with minimal amber, cleaner THC profile, better for activity and focus. Balanced / standard — cloudy-dominant with some amber, full-spectrum effect, most common choice. Sedating / bedtime — significant amber, THC converts to CBN, couch-lock effect ideal for sleep and pain. There's no "correct" answer; the tool shifts its ideal peak score based on what you pick (70 energetic, 80 balanced, 90 sedating).
Check trichomes with a loupe or scope
This is where the tool gets accurate. Grab a 60x jeweler's loupe ($10) or USB microscope ($25), examine the trichomes on a bud site (not sugar leaf — those mature faster and mislead), and estimate percentages: clear, cloudy/milky, amber. The three should sum to 100. Without trichome data the tool falls back to flower-week estimation only (confidence: low). Add pistil browning % as a secondary check — just be aware sativas under-read via pistils because they keep pushing new white ones through late flower.
Read the verdict, check the window, prep accordingly
The tool returns a readiness verdict (too-early → approaching → entering → prime → exit → overdue) and a 3-date window: earliest acceptable chop, peak for your effect preference, latest acceptable chop. When you're within 10 days of peak, expand the prep checklist — it covers stop-feeding timing, flush schedule, dark-period before chop, drying environment targets, and cure duration. Once you chop, the drying and curing phase still matters as much as the harvest window itself.
The daily-check rule once you're in the window
The harvest window for photoperiods is 5–8 days wide; for autoflowers it's 2–4 days. Once trichomes show cloudy-dominant, check daily — the transition from "perfect" to "past-peak" can happen in 48 hours, especially if your room runs warm or you're growing an amber-prone phenotype. Take a daily photo through your loupe/scope; comparing today vs. yesterday is easier than eyeballing absolute color.
What if my window falls during travel, a holiday, or a busy week?
You have 5–8 days of acceptable window (wider for sativas, narrower for autos). Plan the chop day to fit your schedule when possible. The last 10 days of flower don't require nutrient feedings (you're flushing or on plain water), so short trips don't harm plants. But drying and the first week of curing are active steps — don't start the chop process if you'll be away for the critical 5–7 day drying phase. If you must leave, chop before the window opens rather than after (early harvest loses some yield but preserves the buds; late harvest degrades quality).
Why the calculator uses trichomes more than pistils
Trichomes correlate directly with the cannabinoid chemistry you're trying to time (clear = developing, cloudy = peak THC, amber = CBN). Pistils correlate with flower maturity indirectly — plants can have 80% browned pistils while trichomes are still developing THC, especially in sativas where new pistils keep appearing through late flower. Pistil count is a useful glance-check from 3 feet away, but trichomes are the source of truth. If your trichome reading and pistil reading disagree, trust the trichomes.
Trichome chemistry, maturation curves, and why timing matters
The harvest window is a chemistry problem dressed up as a gardening problem. Inside each trichome — those mushroom-shaped glands coating cannabis flowers — is a tiny chemical factory producing THCA (acidic precursor to THC), CBDA, CBGA, and dozens of terpenes. Harvest timing decides what ratio you get. The Harvest guide covers the broader harvest-through-cure workflow; this section covers the biochemistry driving window timing.
3 stages
Trichome color progression
Clear → cloudy → amber. Each stage represents a distinct chemical state. Clear heads are still producing, cloudy heads are peak THC, amber indicates THC degrading into CBN.
~30-40%
Yield loss from early chop
Chopping 1 week before window opening can cost 30-40% of final yield. Final 2 weeks of flower is when plants pack on most weight — leaving early is the #1 mistake.
~50%
THC loss from late chop
Waiting past amber-dominant can degrade THC by 50% or more. THC converts to CBN (sedative, less psychoactive). Potency drops even as weight stays.
What's actually happening in each trichome state
A mature trichome is a glandular structure — a stalk topped with a bulbous head filled with cannabinoid-rich resin. The color you see through a loupe reflects the state of the resin inside:
| State | What you see | Chemistry |
|---|---|---|
| Clear / translucent | Glassy, see-through heads. Minimal resin accumulation. | Still actively synthesizing cannabinoids. THCA levels rising but below peak. Chopping now means losing the majority of potential potency. |
| Cloudy / milky | White, opaque heads. Resin fully packed. | Peak THCA concentration. Dense cannabinoid accumulation. This is the "ready" window for maximum THC-forward chemistry. |
| Amber / gold | Yellow to golden-brown heads. | Oxidation of THCA → CBNA (non-psychoactive precursor to CBN). Also some terpene degradation. More sedative effect, less cerebral. |
The maturity score, explained
The tool calculates a 0–100 maturity score from your trichome observation using weighted averaging. Clear trichomes contribute 0, cloudy contribute 70, amber contribute 100. The weighted average produces a score that reflects where the plant sits on the maturation curve.
Example: 10% clear, 80% cloudy, 10% amber → (0×10 + 70×80 + 100×10) / 100 = 66. This score lands in the "entering harvest window" range — ready for growers wanting energetic effects (peak at score 70), approaching peak for balanced preference (peak at 80).
The peak score shifts by effect preference because different chemistry profiles are "done" at different maturation states. Energetic preference wants mostly cloudy with little amber (peak at 70). Sedating preference wants more amber in the mix (peak at 90). Same plant, same trichomes, different "ideal" window.
Why pistils are a secondary indicator
Pistils — the thin hair-like strands on cannabis flowers — are the plant's reproductive structures. They start white and extended, then brown and curl as the plant matures. Pistil browning correlates with overall plant maturity but doesn't directly track cannabinoid chemistry the way trichomes do. A plant can have 80% browned pistils while trichomes are still developing THCA, especially in sativa-dominant strains where new pistils emerge through late flower.
The tool weights pistil data less heavily than trichome data, and includes strain-specific adjustments — sativa pistils are boosted by +15 maturity points (to correct for under-reading), hybrids by +8. Indica pistil browning is reasonably reliable as-provided. Autoflowers vary too much by strain for a standard correction.
Strain type affects everything
Indica-dominant strains evolved in harsh, short-season climates (Hindu Kush, Afghanistan). They flower fast (7–9 weeks), compact tightly, and have narrow harvest windows (3–5 days of ideal chop time). Trichome transition from cloudy to amber is fast — wait a day too long and you're in CBN territory.
Sativa-dominant strains evolved in equatorial climates (Thailand, Colombia) where flowering can take months. Flower cycles run 10–12+ weeks, plants stretch dramatically, and harvest windows are wider (5–8 days) because amber develops more slowly. The tradeoff: pistils keep pushing out new growth late into flower, making them unreliable maturity indicators.
Autoflowers compress the entire life cycle into 8–12 weeks total (from sprout, not from flip). They don't respond to light cycles for flowering. Trichome development is rapid once it starts — daily checks recommended in the final 2 weeks. Autos often show more amber at peak THC than photoperiods due to genetic variability and stress-sensitivity.
Where the numbers come from
Trichome maturity weights (clear=0, cloudy=70, amber=100) reflect standard cannabis cultivation guidance corroborated across multiple breeder references and peer-reviewed papers on cannabinoid biosynthesis timing. The 10-maturity-points-per-week progression rate is an empirical estimate averaged across photoperiod flower strains; individual strains vary ±30% from this rate. Yield-loss estimates for early harvest (30–40%) and THC-loss estimates for late harvest (up to 50%) come from published grow studies comparing chop timing effects. Prep-timing guidance (stop feeding 10 days, flush 7 days, 48-hour dark period) reflects consensus practice — these aren't optimized for any specific strain, just safe defaults. Serious growers refine each of these based on their specific strain's behavior over multiple cycles.
Common harvest timing questions
How do I know which trichomes to look at — sugar leaves or buds?
Buds, specifically the calyxes (not sugar leaves). Sugar leaf trichomes mature 3–5 days earlier than bud trichomes — if you're reading amber on sugar leaves, the buds are likely still mostly cloudy. Pick a bud site midway up the plant (not a top cola, which gets more direct light, and not a lower bud which matures slower). Check the trichomes directly on the calyx surface. Multiple buds from different parts of the plant give the best average — plant maturity isn't uniform top-to-bottom.
What magnification do I actually need?
60x is the floor for reliable color reading; 100–120x is ideal. Jeweler's loupes at 40x can identify clear vs. cloudy but struggle with subtle amber shifts. USB microscopes ($20–30) go to 100x+ and let you photograph your checks for day-to-day comparison — highly recommended if you're serious about timing. Pocket digital scopes with built-in LCD screens are the sweet spot for home growers: better than loupes, cheaper than microscope rigs. Smartphone macro lens attachments work but are fiddly.
My buds smell amazing but trichomes are still half-clear — can I chop now?
You can, but you'll lose significant yield and potency. Peak terpene production doesn't equal peak cannabinoid production — terpenes often hit their strongest smell 1–2 weeks before peak THC. What smells best doesn't necessarily produce the strongest or heaviest flower. The tradeoff: early chop gives you a lighter, more "fresh" smelling product; full-maturity chop gives you more total weight and potency, though some early terpenes fade during cure. Most growers wait for trichomes and accept that the peak aroma moment is a preview, not the finale.
The tool says "prime window" but my plant still has white pistils — is it really ready?
Probably yes. Trichomes are the primary indicator; pistils are secondary and often mislead. Sativa-dominant strains in particular keep pushing new white pistils through late flower — you can have 30% white pistils even when trichomes are cloudy-dominant and ready. Indicas and hybrids are more synchronized but still variable. If trichome reading says prime and pistils say "wait," trust the trichomes. If your plant is sativa-dominant and you want to verify, check a second bud site — consistent cloudy-dominance across multiple spots confirms readiness regardless of pistil color.
Do I really need a 48-hour dark period before harvest?
The evidence is mixed but it doesn't hurt. Proponents argue 24–48 hours of darkness stresses plants into final resin production, increasing trichome density. Research on this is limited and inconsistent — some studies show marginal effects, others show none. What's clear: the dark period doesn't cause harm, and it's a practical way to ensure you're harvesting during plant dark cycle (when terpenes are highest). If your grow schedule allows, do it. If not, harvesting just before lights-on captures the same terpene peak without the 48-hour lead time. This is a "low-cost, possible upside" step, not a must-do.
My autoflower is at week 10 but trichomes are still mostly clear — is something wrong?
Possibly, but not necessarily. Autoflower timelines on seed descriptions are averages — individual plants vary ±2 weeks. Environmental factors also stretch the timeline: high temps (above 82°F), light stress, root-bound containers, over/under-watering all delay maturation. Check your environment first. If environment looks good, it might just be a slower phenotype — give it 7–10 more days and re-check. Warning signs that something's wrong: persistent yellowing of new growth (nutrient or pH lockout), unusual leaf curl (heat stress or overwatering), or flowers that look underdeveloped compared to normal photos of the strain at this age. The calculator flags the "way past breeder time with low maturity" scenario with a warning prompting these same checks.
Should I harvest all plants at once or stagger based on maturity?
Stagger if you can, especially across different strains. Different strains finish at different times (even with similar breeder-stated flower weeks), and individual phenotypes of the same strain can vary by 1–2 weeks. Harvesting each plant at its own peak produces better quality than chopping everything on one convenient day. For multiple plants of the same strain, the "plant-by-plant" approach adds 2–4 hours of extra work per plant but improves the final product. Many growers harvest the largest/most exposed colas first (often more mature due to light exposure) and leave smaller lower buds another 3–5 days to finish developing — same plant, two harvest rounds.
I missed the window and most trichomes are amber — is my harvest ruined?
No, just different. Amber-dominant cannabis isn't "ruined" — it's sedating chemistry, excellent for sleep aid, pain relief, and evening use. Some growers deliberately push for amber. What you've lost: the cerebral, energetic, focus-friendly THC-forward profile. What you still have: a potent, relaxing, CBN-rich product. Chop immediately to preserve what's there — waiting longer only degrades further. Consider it a single-sleep-strain harvest and adjust your next grow's timing if you preferred the energetic profile. First rule of over-amber: don't panic, don't scramble-chop at 3am; finish the evening and do a proper harvest the next morning.
Harvest, dry, and cure gear
Good harvest timing only matters if you execute the chop, dry, and cure properly. A $15 loupe prevents a ruined harvest. A $30 set of trim scissors produces cleaner buds. A $40 hygrometer pack keeps your cure on track for months. Spend here — it's cheap insurance on 3+ months of grow effort.
Jeweler's loupes & USB microscopes
60x loupes ($10), 100x USB microscopes with LCD ($25–40), handheld digital scopes ($30–60). The single cheapest "pays for itself instantly" upgrade in your whole grow. USB scopes let you photograph daily progress — much easier than eyeballing absolute trichome color.
Trimming scissors & shears
Spring-loaded curved trim scissors ($15–25), stainless straight-blade shears ($20–30), bud scissor sets with cleaner ($40–60). Sharp, precise scissors make trim work 2–3× faster and produce cleaner buds. Pick 2–3 pairs — resin gums them up, you'll be rotating.
Drying racks & hangers
Mesh tier drying racks ($25–60), hanging drying lines with clips ($15), dedicated drying tents with dialed climate ($120+). Drying is half of flower quality — a $30 rack gives better airflow and evenness than hanging on a clothesline in the tent.
Curing jars & Boveda packs
Quart and half-gallon mason jars, UV-protective curing jars ($15–30), Boveda 62% humidity packs ($1–3 each). Proper cure in sealed jars is what separates great flower from average. Boveda packs lock humidity at 62% — no more guessing on daily burps.
Hygrometers for drying & curing
Small digital hygrometers for jar-inside measurement ($8–15), dual-probe temp/humidity loggers ($25–40). Drop one inside each curing jar during the first 2 weeks — you'll know instantly if humidity's too high (mold risk) or too low (cure stalls).
Gloves, aprons, and work surfaces
Nitrile gloves (protect from resin, easier to clean), trim aprons ($20), silicone trim trays with kief screens ($30–50). Resin is sticky and stains; gloves and a dedicated trim tray make the process much less annoying. Kief screens catch sifted trichomes for bonus hash.