# In which weeks of flower do buds grow the most?

> Cannabis buds put on most of their mass from roughly week 3 to week 7 of flower, counted from the first pistil clusters, and keep gaining weight and resin right through the final weeks. In one controlled trial, inflorescence dry weight kept increasing at every harvest from week 5 to week 11. That is why the last weeks need full light and feed: taper nitrogen, don't flush.

- Canonical: https://genetixbay.com/knowledge/answers/when-do-buds-grow-the-most.html
- Topic: Environment · Type: Numbers
- Evidence: Supported · Status: Draft: awaiting expert review
- Full article: [The flip isn't day 1 of flower: the 10–14 day transition and how to count it](https://genetixbay.com/knowledge/environment/flip-to-flower-transition.md)
- Also asked as: When is the bulking phase in flower? | When do buds fatten up? | Which week do buds grow the most? | Do buds keep growing in the last weeks?
- Updated: 2026-10-31 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Short answer

Cannabis buds put on most of their mass from about **week 3 to week 7 of flower** (counted from the first [pistil](https://genetixbay.com/knowledge/glossary/pistil.md) clusters), and they **keep gaining weight and resin to the end**. In a controlled trial, inflorescence [dry weight](https://genetixbay.com/knowledge/glossary/dry-weight.md) rose at every harvest from **week 5 to week 11** [1]. *Supported* that growth continues late; the week-by-week split is *Grower practice*.

## Why

The first two to three weeks after the flip belong to the [stretch](https://genetixbay.com/knowledge/glossary/stretch.md): stem elongation peaks around days 5–10 of short days, then the [shoot tip](https://genetixbay.com/knowledge/glossary/apical-meristem.md) condenses into a [cola](https://genetixbay.com/knowledge/glossary/cola.md) [3]. Little bud mass is built yet.

Once [internodes](https://genetixbay.com/knowledge/glossary/internode.md) stop lengthening, the plant puts its effort into [bracts](https://genetixbay.com/knowledge/glossary/bract.md) and flowers. That's the bulking phase most growers see from about week 3.

It doesn't stop when the calendar says "ripening". Dry weight kept climbing through 11 weeks in one indoor [genotype](https://genetixbay.com/knowledge/glossary/genotype.md) [1], and [trichomes](https://genetixbay.com/knowledge/glossary/trichome.md) keep developing as flowers age [2].

**House position:** the final weeks are when the plant packs on much of its final weight and resin. Pre-harvest [flushing](https://genetixbay.com/knowledge/glossary/flushing.md) and darkness are *Myths* that starve it at exactly the wrong time.

More light means more bulk: yield rose linearly with canopy [PPFD](https://genetixbay.com/knowledge/glossary/ppfd.md) [4].

## The numbers

| Weeks of flower (typical 8–10 week cultivar) | What's happening |
|---|---|
| Flip to ~day 14 | transition and stretch; pistil clusters appear |
| Weeks 1–3 | stretch slows, colas form |
| Weeks 3–7 | fastest visible bulking |
| Final 2–3 weeks | bracts swell, resin ripens, weight still rising [1][2] |

## What to do

1. Count from the first pistil clusters, and log the flip date too.
2. Keep light at full intensity to harvest.
3. Feed normally; [taper nitrogen](https://genetixbay.com/knowledge/glossary/nitrogen-taper.md) over the last few weeks while keeping P, K, Ca, Mg and [micros](https://genetixbay.com/knowledge/glossary/micronutrient.md).
4. Hold late-flower [RH](https://genetixbay.com/knowledge/glossary/relative-humidity.md) at 40–50 % and keep air moving through dense colas.
5. Check the largest buds for rot from week 6 on.

## Common mistakes

- Flushing for the last 1–2 weeks and losing bulk.
- Harvesting by the calendar while buds are still filling.
- Dimming lights for "ripening".
- Ignoring humidity as buds densify.

## Related

- Full article: [The flip isn't day 1 of flower](https://genetixbay.com/knowledge/environment/flip-to-flower-transition.md)
- [How long does the flowering stage take?](https://genetixbay.com/knowledge/answers/how-long-does-flowering-take.md)
- [How do I get bigger, denser buds?](https://genetixbay.com/knowledge/answers/how-to-get-bigger-denser-buds.md)
- [The flush debate](https://genetixbay.com/knowledge/harvest-cure/flush-debate.md)
- Terms: [flowering stage](https://genetixbay.com/knowledge/glossary/flowering-stage.md) · [nitrogen taper](https://genetixbay.com/knowledge/glossary/nitrogen-taper.md)

## Follow-up questions

**Do buds still grow in the last two weeks?** Yes, cannabis buds still gain weight and resin in the last two weeks of flower. In a controlled indoor trial, inflorescence dry weight kept increasing across harvests from week 5 to week 11, and trichome development continues as flowers age. This is why GenetixBay calls pre-harvest flushing and darkness myths: both starve the plant while it is still packing on weight. Taper nitrogen instead.

**When does the stretch stop and bulking start?** The cannabis stretch mostly happens in the first two to three weeks after the flip, with stem elongation fastest from about day 5 to day 10 of short days. Once new internodes stay short and pistil clusters stack at the tops, the plant switches its effort to building flowers. Bulking then runs roughly from weeks 3 to 7 of flower in a typical 8–10 week cultivar.

**How do I get buds to bulk up more?** To get cannabis buds to bulk up more, give them more light within reason, a healthy root zone and steady feeding through the final weeks. Yield rose linearly with canopy light up to 1,800 µmol/m²/s in a controlled trial. Keep late-flower RH at 40–50 % so dense buds don't rot, keep the dark period truly dark, and taper nitrogen rather than flushing.

## Sources

1. Crispim Massuela D, Hartung J, Munz S, Erpenbach F, Graeff-Hönninger S, 2022. Impact of harvest time and pruning technique on total CBD concentration and yield of medicinal cannabis. Plants 11(1):140. https://doi.org/10.3390/plants11010140
2. Punja ZK, Sutton DB, Kim T, 2023. Glandular trichome development, morphology, and maturation are influenced by plant age and genotype in high THC-containing cannabis (Cannabis sativa L.) inflorescences. Journal of Cannabis Research 5:12. https://doi.org/10.1186/s42238-023-00178-9
3. Alter H, Sade Y, Sood A, et al. 2024. Inflorescence development in female cannabis plants is mediated by photoperiod and gibberellin. Horticulture Research 11(11):uhae245. https://doi.org/10.1093/hr/uhae245
4. Rodriguez-Morrison V, Llewellyn D, Zheng Y, 2021. Cannabis yield, potency, and leaf photosynthesis respond differently to increasing light levels in an indoor environment. Frontiers in Plant Science 12:646020. https://doi.org/10.3389/fpls.2021.646020