You're on the right track thinking about LST and light timing to control stretch, but there are a few clarifications and tips to help optimize your strategy:
1. Should You Keep LST'ing Until Flower?
Yes—but gently. LST (Low Stress Training) can absolutely continue through early flower (weeks 1–2 of 12/12), as long as you're not over-stressing the plant.
By week 3 or 4 of flower, most plants stop stretching and redirect energy to bud development—this is when you should stop most training.
If you're still LST’ing lightly in week 4 (like just spreading branches slightly), that’s usually okay. Avoid aggressive bending at that stage.
2. Would It Be Boring?
Not at all. Continued LST = better light spread + more uniform buds. It’s smart, not boring.
3. Tweaking Light Timing to Reduce Stretch?
The idea of reducing light hours gradually before flipping is unconventional, but has some logic:
Decreasing from 18/6 to 12/12 gradually can signal flowering slowly and might slightly reduce stretch.
A more typical method is to go straight to 12/12 but manage stretch through environment and training, like:
Keeping temps consistent between day/night (less than 10°F swing).
Using red light blockers (far red) at lights off, if available.
Keeping light intensity high enough (~800–1000 PPFD) during stretch.
4. Alternative (More Reliable) Stretch Control Options:
Increase blue light ratio if your fixture allows it—more blue = less internodal stretch.
Use plant growth regulators (PGRs) only if you're very experienced (not usually recommended for most growers).
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TL;DR:
Keep LST’ing lightly through early flower (not boring, it's good). If you want to experiment with gradually reducing light hours, it's okay—but don’t expect it to prevent stretch entirely. Better control usually comes from canopy management, consistent environment, and dialing in your spectrum and PPFD.