It broke!!

[SOG420]

A friend if mine accidentally broke the top meristem of two plants 12 days into flowering this comprised of over half the plant on both. he mended the plants using twist ties as well as turning off the oscillating fan for a little while

[IAmKowalski]

Only 12 days into flowering? As long as their is enough outer layer to carry water, they should have pleanty of time to heal just fine. He should make sure the splint is solid and try to avoid jostling or disturbing them. They should form a hard knuckle at the point of the wound.

[SOG420]

Any suggestion on what to use as a splint?

[O'skool]

tooth picks and tape works well... good luck

[IAmKowalski]

Since this is the mainstem I would suggest driving a dowel rod stake down into the soil/medium alongside the trunk and using tape/twist-ties/what-have-you along it's length to help support the plant while it heals, and just leave it in place to help support the bud weight. If you use wire, don't make it so tight that it cuts in as the stem continues to swell.