Does NPK ratio affect when auto flowers?

I know autos have their own built-in timeline. But, I'm wondering if nutrient balance has much influence on that. I used to feed something like 2-1-3 in veg and my autoflower predictably showed sex around 3-4 weeks and had obvious bud sites around 5 weeks. Lately I've been feeding 2-1-1 and they're taking much longer to show sex and bloom.

I'm wondering if that's my NPK ratio, or just genetic flukes that are coincidental to my ratio change?

I'm in the process of shifting the K ratio higher. In time I'll see how that works. Just wondered if this is something that's already well known.

Seems like your just going to low on your flower macros, P and K are more important in flower so if youve noticed less/slower buds proabably a direct correlation with the drop in those 2 macros
Is your soil built up with amendments and what not?

@bf80255 I'm using Pro-Mix HP, Kellogg Patio Plus (outdoor potting mix) and perlite (3:1:1). A light soil (mostly soilless) I used when growing GH Flora 3-part. I may increase the proportion of soil now that I'm using a different fertilizer.

It sounds like you're confirming that autos aren't entirely on their own timeframe. That NPK ratios could cause an auto to veg longer. I'm in the process of bumping K up. I use a silica product in veg. I'm switching to ArmorSi in the next grow. It adds K, unlike Silica Blast which I've been using.

In the past I didn't concern myself with PK levels. The plants started blooming at 4-5 weeks. I switched to "flower" nutes at 6 weeks. I didn't realize NPK ratio contributed to the plant blooming when it did.

If true, that's an interesting development. Usually we're told not to FIM, top, clone, etc. because an auto's fixed lifespan doesn't allow for that trauma (and recovery). If an auto can be held in veg longer with 2-1-1 (low K, high N), that's could be a useful tool.

I dont think its so much being held in veg as being stunted and taking longer to form flowers, always seem to yield less when they get fucked with imo aside from lst

bf80255 said:

I dont think its so much being held in veg as being stunted and taking longer to form flowers, always seem to yield less when they get fucked with imo aside from lst

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I don't know if stunted is the right word. They're lush green, turning into monsters. It seems like they have a special NPK requirement for the "auto" part to function faster(?). I've never heard of autos having such a requirement.

But, it will be interesting to see how higher K affects the next one. I'm more concerned with time than yield. (As healthy and large as the plant is, I'd assume it would have better yield resulting from longer veg. If I got better yield faster using more K I'd be doubly happy.).

I'll update this thread in a couple months after trying the next one at higher K.

az2000 said:

I don't know if stunted is the right word. They're lush green, turning into monsters. It seems like they have a special NPK requirement for the "auto" part to function faster(?). I've never heard of autos having such a requirement.

But, it will be interesting to see how higher K affects the next one. I'm more concerned with time than yield. (As healthy and large as the plant is, I'd assume it would have better yield resulting from longer veg. If I got better yield faster using more K I'd be doubly happy.).

I'll update this thread in a couple months after trying the next one at higher K.

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Interesting theory i look forward to the update and results

az2000 said:

@bf80255 I'm using Pro-Mix HP, Kellogg Patio Plus (outdoor potting mix) and perlite (3:1:1). A light soil (mostly soilless) I used when growing GH Flora 3-part. I may increase the proportion of soil now that I'm using a different fertilizer.

It sounds like you're confirming that autos aren't entirely on their own timeframe. That NPK ratios could cause an auto to veg longer. I'm in the process of bumping K up. I use a silica product in veg. I'm switching to ArmorSi in the next grow. It adds K, unlike Silica Blast which I've been using.

In the past I didn't concern myself with PK levels. The plants started blooming at 4-5 weeks. I switched to "flower" nutes at 6 weeks. I didn't realize NPK ratio contributed to the plant blooming when it did.

If true, that's an interesting development. Usually we're told not to FIM, top, clone, etc. because an auto's fixed lifespan doesn't allow for that trauma (and recovery). If an auto can be held in veg longer with 2-1-1 (low K, high N), that's could be a useful tool.

Click to expand...

silica blast contains potassium. even says so on the bottle lol...
the product's chemical name is potassium silicate solution.

taken from the botanicare website @ http://www.botanicare.com/Silica-Blasttrade-P53.aspx#

Q: Why is there potassium in Silica Blast? Will the potassium in Silica Blast be a problem if I apply Silica Blast during bloom?
A: Silica Blast contains potassium because the source of silicate used in the formula is potassium silicate, which is one of the few plant-available sources of silica for plant nutrition. The potassium provided by Silica Blast will not cause any nutrient problems during bloom, due to Silica Blast’s relatively low applications rates (and subsequently low contribution of potassium to the nutrient solution).

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reducing nitrogen level ratios in photo strains after 2 weeks flower
has always brought about faster flower maturation IME.

adding amorphous diatomaceous earth is another way to increase
plant available silicates. IME using silicates they cause the plant to
use nitrogen much more efficiently. you can use the same amount
of N that you were using before starting a silicates regimen, but the
plants will show some signs of nitrogen toxicity such as shiny, leathery
looking leaves. not an issue if your nitrogen levels are low to begin
with, but if you have an amended soil and are feeding a veg fert (in my
case i was using pure blend pro veg) it can show some signs of N
toxicity.

indianajones said:

silica blast contains potassium. even says so on the bottle lol...

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Thanks. I should have said a more significant source of K. Botanicare SB is 0.5% and ArmorSi is 4%. The label says to use half as much. But, half the volume of AS still contains considerably more K. I was thinking of it as a way to increase K without adding a new component to what I feed.

indianajones said:

IME using silicates they cause the plant to use nitrogen much more efficiently. you can use the same amount of N that you were using before starting a silicates regimen, but the
plants will show some signs of nitrogen toxicity.

Click to expand...

Thanks, I didn't know silica can contribute to N toxicity. However, I've been using SilicaBlast for over a year. The only thing that changed when my auto flowers slowed down was my base nutrients.

I was using GH Flora Series with the "useless" schedule. In veg I was feeding NPK ratio 2.06-1.00-3.31. (That doesn't count the small contribution of K from SilicaBlast.).

I changed to Grow More Sea Grow "All Purpose" which is 1-1-1. The only thing I can think could cause the slower "auto" characteristic is lower K. With ArmorSi it is 1-1-1.5. I can add in some "Flower and Bloom" to get a ratio like 1-1.5-2.

The only other thing which changed with the last two grows is that temperatures were higher. For example, nighttime temps didn't fall below 83 whereas previous grows experienced 65-75 at night. Maybe this is what slowed the "auto" characteristic. If there was a peculiar nutrient requirement for autos I think I would have found discussions about it when I googled. I.e., I can't believe I stumbled onto something like this before a million other people did.

BTW: I created a spreadsheet to play with NPK ratios.(<<link). That's been interesting to see actual NPK, for example after adding CalMag+, or replacing it with CaMg+ which has no N. (If anyone downloads it, be aware I'm close to uploading a new version.).

BTW: I really like the fertilizer I'm using now. I notice a significant taste difference compared to GH Flora 3-part. Deeper, richer. It's cheaper too. About $1 per plant for the entire grow.

i only work with autos jus now done a fair few 12&12 i have 5 on the go @ the moment 1 is from AUTO SEEDS its called pounder on reading up on it its suppose to be 1 of the biggest yielding autos out there has anyone done this plant before can tell me anything what they got from it and how long you gave it etc also 1 other i have never done is ULTRAVIOLET FROM SAMSARA SEEDS this says 45 to 55 days what's the fastest plant i have had i thought the 60 wonder would be 1 of the fastest again anyone got any info on this 1 plz

Just an update. I remembered I started supplementing with AK Kelp when my autos got slow. I've read Kelp contains growth hormones and can interfere with photosensitive flowering (large doses, or a certain type of kelp?).

So, I'm thinking that's the variable. It's either heat, nutrient change (lower K in veg), or kelp. The nutrients I changed to already have kelp. So, the fact that I've read kelp can interfere with transition to flower, and I inadvertently doubled up on the kelp, I'm willing to bet that's it.

I raised K about 3-4 feedings ago, and stopped adding AK Kelp after 2-3 feedings ago. I'm seeing bud sites developing. I'm not going to know which was the culprit until another grow when I try AK Kelp again. I won't be able to rule out heat until next spring.

(@jgibson it's best to start your own thread. You'll get more attention with a more specific topic.).