NPK during flower - can anyone agree?

Ok, so being my first grow, I’ve researched EVERYTHING about nutrients and when/what to feed and the results I came up with are absolutely inconclusive. This is what I’ve read:

1. High N for veg, lower it during flower and increase P & K

2. High N for veg and keep it high all through flower as plants need N their whole life

3. Balanced NPK throughout complete grow cycle

4. Lower N during flower, increase K and moderate P

5. Lower N and K during flower and
Increase P

So which is it? If one of these were correct and the others weren’t, wouldn’t there be some sick plants and crappy yields happening? Does anyone actually know what cannabis requires for nutrients during flower? If so, please enlighten me. Thanks.

You are about right.
If you go to the grow store and look at the "grow" and "bloom" formulas, you will see something like 10-5-4 for veg or 1-5-6 for flower.
N high in veg, low K.
The P is a usually the same in both stages, since most sources of phosphorous slow release or insoluble.
Higher in K and lower in N for flower.

I typically taper off the N around now outdoors. Although some plants respond differently.. When the light hours begin to change I slowly start adding in some bloom feed and reduce veg feed..

As the plants enter the later stages i pull back everything and just water till they loose almost all the leaves due to yellowing. If the weather chill but dry in oct. it helps finish them nicely.

Seawood said:

1.

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Yes. For the first two weeks of flower reduce N by a little. The plants use N during the transition/stretch phase. By week 3 you drop N but still need a little (strain dependent of course). GSC seems to hold onto N like a bitch so be on the look out for those genetics.

Seawood said:

2.

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No. You could get N toxicity and the bud to leaf ratio will favor leaves.

Seawood said:

3.

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No. P and K especially K need to be increased substantially in flower(weeks 2-6), Mg,Ca and S too (especially in coco). In veg (days 40+) N will have to be applied until the leaves are a nice green (not too light and especially not dark green with a waxy look) same with K,Mg, and Ca (in veg).

Seawood said:

4.

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Yes.See above.

Seawood said:

5.

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No. Increase P and K but decrease N.

Seawood said:

wouldn’t there be some sick plants and crappy yields happening?

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You have to read the plants.

As far as 2 and 3 go, I did an experiment with that a few grows ago on two auto plants. Both were in 7 gallon smart pots. I used Dyna Gro Foliage Pro and Pro-Tekt on one plant and on the other I used Foliage Pro and Pro-Tekt until about the second week of flower when I switched over to bloom and Pro-Tekt, only using FP a couple times when I noticed a slight N deficiency.
I harvested, dried, and cured. The final totals of the plants weren’t too far off. The plant that I used grow nutes only had maybe an 1/8th more total. I always have someone test my flowers out since I don’t smoke, giving them a bud from each and they told me both were good, one not being any better than the other.

Hardly scientific but it goes to show that you can use grow nutes the entire plants life with good results. That said, I haven’t done it since and think the plants are better off with bloom nutes in flower.

The ideal NPK depends on whether you're in hydro or growing in containers with coco/peat/soil.

homebrewer said:

The ideal NPK depends on whether you're in hydro or growing in containers with coco/peat/soil.

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I’m outdoors in pots/soil. So I should be using a fert that is low in N but high in P & K, correct? Does it really make that much difference? I have MG Bloom nutes which is 15/30/15 but not sure this is ok. I can try to get something better today if this isn’t a good option. Thanks.

Starting to get concerned that these plants won’t finish in time...most guys are chopping first week of October here. Plant in pic is the farthest along.

Seawood said:

I’m outdoors in pots/soil. So I should be using a fert that is low in N but high in P & K, correct? Does it really make that much difference? I have MG Bloom nutes which is 15/30/15 but not sure this is ok. I can try to get something better today if this isn’t a good option. Thanks.

Starting to get concerned that these plants won’t finish in time...most guys are chopping first week of October here. Plant in pic is the farthest along.

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Ideally outdoors you'd start with organic soil (because it's likely cheap to make) and as the soil loses its juice throughout the season you'd start feeding with a complete and balanced mineral-derived plant food (something like a 5-5-5). It's more of a science indoors but that same 5-5-5 from start to finish would do far better than any 'bloom specific' formula.