this is a copy/paste from a RIU member called jela10.....(not my words, as I have never used PK 13/14)
PK 13/14, a mixture of phosphorus and potassium, added at just the right moment of the flowering phase will get you some bonking big buds.
Some here on RIU note a surprising difference within 24 hours of the first addition.
In short, Phosphorous strengthens cell formation in flowers and Potassium helps the plant generate the sugars necessary for ample flowering.
Based on Canna’s grow charts, the perfect moment is decided by reading the plant and the additions don’t last more than a week of feeds.
The issue here is interpreting the chart’s wording.
Canna breaks down the 12/12 flowering period into 4 phases, “Generative Period 1-4. PK add’s are in period 2, described as “Development of the volume (breadth) of flowers or fruit”.
Someone here on RIU interprets this as the time when you notice all vertical growth is over on the flowers and they have just begun to swell up.
I’ve fine-tuned this to another signal and that’s when the small puff balls start linking together to form the cola.
I simply look for minimal segmentation along the stem, which was rough to tell with this SK OG stain.
Weirdly enough, a lot of the strains I’ve grown show this trait during the end of week 4, or start of week 5.
So that may be key for people with 8-week strains that form golf balls instead of colas.
Guess what “Generative Period 3” is? It’s described by Canna as “The development of the mass of flowers or fruit”.
So be warned, after the start of these additions, buds start fattening horizontally at an amazing rate, so vertical development stops.
This is the reason I waited till week 6-7 on this SWOG strain, I was simply waiting for vertical fill-in before starting the fattening.
For length of time on additions, I run for 3 feedings which is about 9 days.
I tell people to reduce their base nutes ˜1-2ml/gal since PK is some hot stuff, but then again…you can read your strain.
If they take everything you throw at them, give the full dose of base nutes.
I am guilty of some little brown leaf tips most of the time during PK adds, but in turn get some awesome returns from the plant bud-wise.
As for starting pk13/14 adds, the sweet spot for me is sometimes late week 4 but mostly week 5. When the small puff balls of buds just start connecting up and down the colas is the time to start.
You don't want to go more than 7-10days (about 3 feedings for me) or the plants start getting really "ragged" looking.
I drop my base nutes about 2ml/gal as well to reduce tip burns. It is some hot stuff.
