When do you PK boost?

[theother]

When do you PK boost, not really in terms of weeks but more in relation to what the plant is doing. ie right at the beginning of flower set, or right after everything has stacked.

It would also be helpful if you gave some insight into your system, ie rdwc, flood and drain, coco, dirt, etc.

This is something I have been curious about for a long time, I don't know that there is a right answer, I do what is right for my garden, but I think it will help a lot of people get some insight into when it is most effective.

I usually spike the feed when I see the plant stop stacking, sometimes I think I miss my window other times it seems spot on, it does seem to be a question of timing though. I also boost pk a bit late in flower, but not at the levels I do during that initial boost. btw I am in coco, so a prolonged period of super high PK is not really an option.

 

[Jnugg]

With 8 to 9 week strains I would recommend starting a pk boost around weeks 4 through 6.

 

[Homebrewer]

When do you PK boost, not really in terms of weeks but more in relation to what the plant is doing. ie right at the beginning of flower set, or right after everything has stacked.

At no point in the life cycle of a plant are the P and K needs elevated. In water culture, one may make the observation that the N needs of the plant decrease a little after the stretch but this is not the time, IMO, to back off the N only to add more P and K. Balance is key at all times.

 

[Lester Beans]

I run hydro and add Big Bud by AN when the plants stop stretching. Also this is when I start CO2. For a hybrid that finishes between 8-9 weeks that would be around the beginning of the 3rd week and I run it until mid 6th week.

 

[theother]

At no point in the life cycle of a plant are the P and K needs elevated. In water culture, one may make the observation that the N needs of the plant decrease a little after the stretch but this is not the time, IMO, to back off the N only to add more P and K. Balance is key at all times.

Interesting, so you are all about ratios. I am inclined to agree with you. I do it with a slight twist though, I switch the ratio after flower set, then I begin to creep up the ec until I top out where I want to, process takes maybe 2 weeks to get up and a week or two to come back down. The whole process varies the EC by maybe .3

My logic might be dictated by fear of salt buildup however, I would never run my peak ec numbers all the way through, but I am kind of afraid to finish of a cycle without a bit of a spike, no evidence to back that up, just experience/popular wisdom.

 

[holystomata]

At no point in the life cycle of a plant are the P and K needs elevated. In water culture, one may make the observation that the N needs of the plant decrease a little after the stretch but this is not the time, IMO, to back off the N only to add more P and K. Balance is key at all times.

So what do you consider a balance in flower?

Sorry i don't understand. I thought the point was to back off N to give a little more ec room in the solution for P and K? And that plants in flower use more PK than plants in veg so we boost?

Why do you add more P and k if the plants don't have an elevated need?

 

[One2Lurk]

I think the logic behind reducing N during flower relates to attempting to reduce the leafiness in bud production (somewhat effective, but influenced more by genetics IMHO). Boosting P&K during flower probably isn't really beneficial in most circumstances. Liebigs law tells us that growth is not regulated by the totality of resources available. But rather by the scarcest resource (limiting factor). In other words, more P&K won't help... Unless you've used up ALL that you started with.

And for Pete's sake, if your growing in Promix, or Sunshine mix... Stop trying to adjust the ph of your water/nutes. It won't help, I'd bet a dollar things just keep bouncing around if you do. That whole pot full of peat, limestone, and other various buffers within will simply cling to the acid/base that you add forming an unpredictable bond that WILL throw your ratio further out of whack. Ph-/+ is really only for hydro. Even then it's probably better and easier to simply start with clean pure water rather than make big adjustments.