Short answer, in plain words. Topping (cutting off the top) and LST (bending and tying the plant down) chase the same thing: lots of tops at the same height, all in good light. LST gets there without cutting. The founder is personally against topping most of the time and prefers simple LST, because plants react to cutting very differently: some hazes lost heavy clone-taking "without blinking", while other cultivars crash or even die from losing a limb (founder's field experience) [6]. The research is thin, so the honest answer is: it depends on the cultivar; test yours.
What do topping and LST each do?
Both break the plant's habit of growing one main cola. Established (plant physiology).
- Topping removes the growing tip. The tip makes auxin that suppresses the side buds below it (apical dominance); take the tip away and the two shoots below take over [5].
- LST bends the main stem sideways and down. The tip is no longer the highest point, so side branches rise to meet it, and the canopy flattens without a cut.
- Why it pays: light falls off down the canopy, yield follows light [4], and lower, shaded buds have lower cannabinoid concentration [1]. A flat canopy puts more bud sites in strong light.
Topping
Cut the tip
- +Fast, predictable split into two main tops
- +Pairs well with SCROG
- −Recovery time: days of slower growth
- −Some cultivars handle losing tips or limbs badly (founder's field experience)
- −Risky on stressed or small plants
Simple LST
Bend and tie
- +No cut, no recovery stall
- +Works on autoflowers and sensitive cultivars
- +Adjustable every few days
- −Needs regular attention in veg
- −Stems lignify; bend early
The founder's default most of the time.
What does the research show?
Not much, and nothing comparing topping with LST directly. Supported for canopy shape; grower practice for the comparison.
- Pruning can raise yield on large plants. On large (about 2.5 m) greenhouse plants of a CBD-dominant medical cultivar, pruning twice was the only architecture treatment that raised flower yield per plant, with cannabidiolic acid rising from 14.1 to 22.5 g per plant [1].
- Opening the canopy evens out potency. Removing lower branches and leaves let more light in and raised cannabinoid concentration in the lower buds, improving uniformity [1][2].
- Density changes the answer. Higher planting density increased yield per area but reduced cannabinoid uniformity, and architecture treatments interact with density [3].
- No study has compared topping with LST, or tested small indoor plants and high-THC cultivars the same way.
- 14.1 → 22.5 gCBDA per plant with pruning twiceLarge greenhouse plants, one CBD cultivar
- 0Controlled studies comparing topping with LST
Source: [1]
Why is it cultivar-dependent?
Plants differ in how quickly they regrow from a cut and how much leaf and root they can afford to lose. In the founder's experience, some hazes kept growing through heavy clone-taking as if nothing happened, while other cultivars stalled for days or died after losing a limb (founder's field experience) [6]. Young, stressed or root-bound plants recover worse (see recovery after topping).
How do I test my own cultivar?
A split-clone side-by-side. Grower practice; the method GenetixBay uses for every open question.
- Matching clonesSame mother, rooted together
- Same everythingPot, light, feed, veg time
- Half topped, half LST
- RecordRecovery days, canopy days, top size, dry yield
- Repeat once, then decide
Source: GenetixBay grow-journal method [6]
Record: days until regrowth after topping, days to a full flat canopy, top-cola size, dry yield per plant, and a lab test if you can. Post it as a GenetixBay grow journal so others growing the same cut can compare.
Common mistakes
- Topping every cultivar by default without watching how it recovers.
- Topping young, stressed or root-bound plants.
- Topping after the flip, when recovery costs flowering time.
- Bending lignified stems hard and snapping them (supercropping is a deliberate technique; see LST).
