# Topping: cutting the main tip for more colas

> Topping removes the main growing tip above a node so the two shoots below take over, breaking apical dominance and producing a flatter plant with more main colas. Top healthy plants with 4–6 nodes, cut just above the chosen node, and allow 5–10 days of recovery before flipping to flower. In one controlled study, pruning twice (at transplant and at the switch to flower) gave the highest flower and cannabinoid yield per plant.

- Canonical: https://genetixbay.com/knowledge/training/topping.html
- Category: Training · Level: Beginner
- Evidence: Supported · Status: Draft: awaiting expert review
- Stage: Veg · Systems: Any system
- 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)"

## Questions and answers

**When should I top my cannabis plant?** Top a cannabis plant once it has 4-6 nodes, roughly 3-4 weeks from seed, and is healthy, well rooted and growing vigorously. Topping weak [seedlings](https://genetixbay.com/knowledge/glossary/seedling.md) earlier stalls growth, and topping stressed, [root-bound](https://genetixbay.com/knowledge/glossary/root-bound.md) or sick plants is a common mistake. Do the last top at least 7-10 days before switching to [12/12](https://genetixbay.com/knowledge/glossary/12-12.md), and avoid topping in flower, which costs yield time.

**Where exactly do I cut when topping?** When topping, cut the main stem 3-5 mm (⅛-¼ in) above the chosen node, leaving both side shoots at that node intact. Use clean, sharp scissors wiped with 70% alcohol. Cutting below the node removes the very shoots you wanted to grow. Within about a week, two shoots at the cut node should be growing at equal speed.

**Does topping increase yield?** Topping can increase cannabis yield, but the evidence is one controlled study. On large greenhouse plants of a CBD-dominant cultivar, pruning twice, at [transplant](https://genetixbay.com/knowledge/glossary/transplanting.md) and again at the switch to flower, was the only architecture treatment that raised flower yield per plant, with [CBDA](https://genetixbay.com/knowledge/glossary/cbda.md) rising from 14.1 g to 22.5 g per plant. Small indoor plants and high-THC cultivars may respond differently.

**Can I top [autoflowers](https://genetixbay.com/knowledge/glossary/autoflower.md)?** No. Don't top autoflowers; use [low-stress training](https://genetixbay.com/knowledge/glossary/lst.md) instead. An autoflower runs on a fixed clock from germination, so the recovery time topping demands, typically 3-7 days before visible regrowth, comes straight out of its growing time. The GenetixBay house position is that topping will never produce what proper LST does on an auto. This is grower practice rather than controlled research.

**How many times can I top a plant?** You can top a cannabis plant repeatedly, topping each new main shoot again after it grows 2-3 new nodes, which doubles the [tops](https://genetixbay.com/knowledge/glossary/top-shelf.md) each round: 2, then 4, then 8. Each round needs 3-7 days before visible regrowth, so every extra top adds veg time. Finish the last top at least 7-10 days before the flip, and combine topping with LST to spread tops apart.

**Topping vs FIM: which is better?** Topping is the more predictable choice: cutting cleanly above a node reliably gives two [co-dominant](https://genetixbay.com/knowledge/glossary/codominant.md) shoots. FIM, which pinches off most of the tip instead, can give three to five shoots but often gives only one or two. No controlled cannabis study has compared them. Either way, the gain comes from a flatter canopy with more tops in good light, so pair either one with LST.

**Short answer.** [Snip](https://genetixbay.com/knowledge/glossary/snp.md) the main stem's growing tip just **above a node** once the plant has **4–6 nodes** and is growing vigorously. The two side shoots at that node become co-dominant, and lower branches catch up, giving a flatter canopy with more tops at similar height. Let the plant recover **5–10 days** before flipping to flower. In a controlled trial on large greenhouse plants, **pruning twice** (at transplant, leaving six main branches, and again at the switch to short days) was the only architecture treatment that increased flower yield per plant over the control; [cannabinoid](https://genetixbay.com/knowledge/glossary/cannabinoid.md) yield rose too (e.g. CBDA 22.5 g vs 14.1 g per plant) [1].

## What's happening

The apical tip makes auxin that flows down the stem and suppresses side buds (apical dominance). Remove the tip and the suppression lifts; the nearest buds grow out. An [even canopy](https://genetixbay.com/knowledge/glossary/even-canopy.md) also matters because light falls off with depth, and yield follows light [3]; lower, shaded buds in cannabis have lower cannabinoid concentration [1].

## How to do it

1. Plant healthy, well rooted, 4–6 nodes (or 3–4 weeks from seed).
2. Use clean, sharp scissors (wipe with 70 % alcohol).
3. Cut the main stem 3–5 mm (⅛–¼ in) above the chosen node, leaving both side shoots intact.
4. Optional: top again on each new main shoot after 2–3 new nodes (gives 4, 8, …).
5. Combine with [LST](https://genetixbay.com/knowledge/training/lst.md) to spread new tops apart.

## Numbers that matter

| Item | Typical | Notes |
|---|---|---|
| First top | 4–6 nodes | Earlier tops on weak seedlings stall growth |
| Recovery | 3–7 days before visible regrowth | |
| Last top before flip | ≥ 7–10 days before 12/12 | Avoid topping in flower; costs yield time (*Grower practice*) |
| Autoflowers | Don't top; use LST | Topping never produces what proper LST does on an auto, and it costs recovery time on a fixed clock (house position, *Grower practice*) |

## How to confirm it worked

Within a week two (or more) shoots at the cut node are growing at equal speed; by flip the tops sit within ~10–15 cm (4–6 in) of each other.

## Common mistakes

- Topping a stressed, root-bound or sick plant.
- Cutting below the node (removes the side shoots you wanted).
- Topping in flower.
- Topping autoflowers. Use [LST](https://genetixbay.com/knowledge/training/lst.md) instead.
- Topping, then leaving the canopy uneven with no LST.

## Evidence

Apical dominance is *Established* plant physiology. Yield increase from double pruning is *Supported* by one controlled study on large (~2.5 m) greenhouse plants of a CBD-dominant medical cultivar [1]; small indoor plants and high-THC cultivars may respond differently. Topping vs not topping at commercial densities shows that density and architecture interact [2].

## Sources

1. Danziger N, Bernstein N, 2021. Shape matters: plant architecture affects chemical uniformity in large-size medical cannabis plants. Plants 10(9):1834. https://pmc.ncbi.nlm.nih.gov/articles/PMC8468686/
2. Danziger N, Bernstein N, 2022. Too dense or not too dense: higher planting density reduces cannabinoid uniformity but increases yield/area in drug-type medical cannabis. Frontiers in Plant Science 13:713481. https://doi.org/10.3389/fpls.2022.713481
3. 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