HELP! PK 13\14 When? How much? How many times?

[Bartholomew]

The Canna custom schedule @ http://www.canna-uk.com/growguide says once? during Generative phase 2. At the same time I've heard Neil from growpotcheaply youtube say three times. Once at the beginning of flowering, once mid flowering and once at the end.
Any general guidelines for PK 13\14. I know it's heavy stuff and should be used sparingly, easy to burn plants with it.

Thanks

[RosettaStoned]

I use Canna as well. I supplement the whole flower stage using a little to start and going up as the weeks move forward. I haven't heard the three time usage. I'll try that next grow.

[Bartholomew]

Results? Burn?

[RosettaStoned]

Maybe slight tip burn, they don't hate it though