Defoliation without stalling the plant

Take no more than a third of the fan leaves, and only from the lower two-thirds, once the stretch has stopped. Do it in one pass, not a little every day, so the plant has a clear before-and-after to recover from instead of a constant low-grade stress.

When to cut

Wait until the stretch is done, usually a week or two into flower, once height gain has slowed to almost nothing. Cutting during the stretch removes leaves the plant still needs to fuel that growth, and you'll see it stall.

The other signal worth watching is light penetration. If you can't see the lower third of the plant from directly above without moving a leaf aside, it's time.

How much

A third of total fan leaf mass, taken from the lower two-thirds of the plant. Leave the leaves directly feeding the top colas alone, those are doing the most photosynthetic work per leaf of anywhere on the plant.

Go slower than feels right the first time. You can always take more next week. You can't put a leaf back on.

Signs of stall

A stalled plant shows almost no new growth for five to ten days after a heavy defoliation, sometimes with slight yellowing at the margins of the remaining leaves as the plant reallocates what it has left. It usually recovers on its own, but it costs you real time in a season that's already short.