How much N P K does a plant need? Can anybody tell me the needed ppm for each nutrient? I want to know how the lucas formula is balanced.
I wonder if Lucas formula 8-16 is overfeeding the plants. I often get an ec of 2.4
How often would you need to rinse a motherplant with plain tap or ro water to prevent salt build up?
Google the Ironhead Method, it’s an update to Lucas Formula that I find works better.
There is a calculator towards the bottom of page that breaks down NPK into ppm.
https://www.angelfire.com/cantina/fourtwenty/articles/profiles.htm
QA, lucas method,
https://web.archive.org/web/20150203032329/http://asklucas.com/index.html
That was so long ago now, and I was around when he posted that up on Cannabis World if I remember correctly.
I was so new back then, and did not have a true idea of how the root mass got the goodies.
But to me that formula is like a stabbing victim, if your stabbed on the street, it could be your end.
If your stabbed by a surgeon, it’s part of a procedure, but stabbed never the less.
To ask what NPK value is useful, I’d ask when during the plants time line?
NPK for seed starting is being stabbed in the street, it will die. They do not need anything then.
NPK, after 4-6 points on a seedling, the grower (surgeon) will apply a tiny portion of all three in equal proportions.
I know this analogy is not correct exactly, but every attempt I made with Lucas, my plants were always hungry for something .
Also back then, most bottled nutrients were following standard outdoor nutrient profiles, so almost every N product was very potent.
Outdoor plants can run off excess nutrients, indoor grower, not so much. That excess stays in the base or in the saucers, getting more and more toxic. That is why so many leech, or flood flush scenarios are around , to rid the root mass of excess.
So much has changed.
I say just use N properly with various degrees of potency at the proper time.
When I mix up or blend my medium, I use like 4 different N suppling organics, to build my mix. Their P K values vary, but I still keep note of them, so when I add P K items I keep the balance.
Sorry just my $.02
thanks. so in the second link it says N with lucas formula is 120ppm. But there are shown feeding values for growth which are like 250-350 ppm for N. So that means lucas formula is on the low end for growth what concerns N?
he also writes:
if you want to play with nutes in veg, that are different than in bloom, consider using more nitrogen in veg than the Lucas formula provides. The Lucas formula is strictly 0-8-16 for bloom.
if you want to see some real Nitrogen driven growth in veg, try the standard GH recipe of 15-10-5 :-)… That is what is in the bottle of Flora Nova Grow btw, and it works really well for vegging…
I took clones from my motherplant, which seemed to be deficient of something. The clones leaves have a slight yellow. Is it possible and recommende to foliar feed the clones or will the clones burn away(no roots yet)? What concentration would be good? I only have the micro and the bloom of GH.
Also I need to get my motherplants healthy. If I foliar feed them how fast would I be see a difference? I foliar fed a half strength solution two times (two days) but see no difference yet.
Sorry still new to this, I dont know the answer to your questions.
Is this runoff EC?
What medium are you using? Some soils come with a starter load of nutes, if this is the case than this could explain 2.4EC.
I will say this about Lucas method, my last grow I feed every time I watered and had a nice green plant all the way to the end. The grow I’m on I tried water feed water and my plants yellowed on me. Still lots of big dense buds but I have to believe that I left some “potential” off the table.
This from Lucas sticks out to me,
“fwiw, nutes do not affect yield, they affect health. Any nutes that produce health, produce yield. There is no magic ingredient that will change your plants from schwag to dank, its the genetics, and the ability to be healthy and achieve their potential, that makes plants phat.”
Photo, haven’t tried autos.
I am still learning autos.I have a very hard tap water and It s hard to me to Dial in the nutes with 200 ppm tap water
what is water feed?
Hey @SamandMax check out my grow journals, I use the Micro and Bloom from GH and keep all my recipes documented:
Alternating between water only and water with nutes.
you did a grow solely on water? Does that make sense?
Hope this helps.
No, I use sunshine#4 as my medium.
As I said my first plant grown with Lucas method I mixed water with 8ml micro/16mlgrow per gallon and feed with this every time I watered. I also flushed at 4 weeks in veg, once again when I switched to flower and once again 5 weeks into flower to control salt build up. This plant stayed green and healthy all the way through.
On my second and current grow with Lucas I decided to feed every other watering, so water/feed/water. I thought this would be a better way to control salt build up. This was a mistake as my plants yellowed upon entering flower and stayed that way.
This is runtz feed lucas every watering with flushes. Full power light right to the end
This is power plant, Lucas water/feed/water/feed. Plant lacked enough nutes for light intensity(yellowing top growth). Light down to 60% at end.
you mix the solution every feeding? I need something for a big reservoir.
I use large pots of coco and drain to waste, removing runoff every feeding. I have 2 plants in flower at any given time, and then a handful of seedlings or clones in veg. I mix up a 3g bucket every two or three days depending on how far along the flowers are. Mid-flowering, they each drink almost a gallon daily.
I like to mix my nutrients and use them within 72 hours as longer than that, I find that I start seeing scum and bacteria build up on the surface of my bucket. This stuff just doesn’t sit around well for days without a circulation system or airstones.
What is your grow setup? How many plants do you have? How large is each container? What medium are you using?
Either way, if you’re running a drain-to-waste setup where you feed and then throw away the runoff, you can use my recipes just scale them up by volume. If you’re doing a recirculating system, you’ll want to target a higher concentration of nutrients as the plants will deplete the solution over time as the system recirculates.
yes. don’t do 8-16.
5-10 is the way to go. Almost any stage and any plant will do good with that (Aside from seedlings, in which case dilute by 50% with water).
You also want a cal-mag supplement to feed as well. (Micro, Bloom, Calmag.)
You’ll have less fluffy buds this way as well.
But I think Lucas Formula is short on nitrogen already. So diluting it down would make that worse.
there’s 2.5x the nitrogen in the Micro than there is in the grow. That’s why you can do without the grow. 5-10 I got that from some big players, so trust it works. 
But you always need to supplement some cal-mag. That is critical!
You only dilute for seedlings. But 5-10 for all other stages.
