20-20-20

[Clawhammer]

Talking about macro nutrients only, I want to switch to using only 20-20-20 fertilizer, convince me otherwise.

I don't believe I have ever blasted a bud because of using 20-20-20 on flowering plants and that ratio should cover all their macro nutrient needs. I grow inside and most of my plants are growing leaves/bulbs or roots at the same time as flowering so I am thinking balanced is the way to go. It would save time watering as well.

On a side note I water 1/4 strength for all waterings except for the 1st-7th of each month where I water with plain water.

[Roberta]

Orchids need so little fertilizer, I doubt that the precise formulation matters much at all, especially at low strength. (it might make things a little too acidic with very pure water, the formulation has extra phosphorus mostly to compensate for the alkalinity of most tap water... worth checking if using RO/DI water, I doubt that it's a problem, just something to measure occasionally)

[Ray]

Nitrogen is the most important nutrient. Based upon tissue analysis, the demands for P & K are a few percent of the nitrogen demand, and are stored in excess in plant tissues for later use, if necessary.

I know a growing in California who feeds using calcium nitrate most of the year, adding a "complete" fertilizer about twice a year.

[Clawhammer]

Originally Posted by Ray

Nitrogen is the most important nutrient. Based upon tissue analysis, the demands for P & K are a few percent of the nitrogen demand, and are stored in excess in plant tissues for later use, if necessary.

I know a growing in California who feeds using calcium nitrate most of the year, adding a "complete" fertilizer about twice a year.

Thanks Ray, your input has been really helpful across several threads where I am trying to determine the best way to water and feed my plants; balancing effort, efficacy, and cost for my conditions and indoor setup.

My goal here is to reduce effort and maintain efficacy by using only one fertilizer as I was previously using both a bloom booster for those in spike and a balanced fert for those in vegetative growth.

Are you advocating the best single use fertilizer would be something with a higher nitrogen content? Would you water a orchid in spike with 12-1-1 or 30-10-10 (I'm talking ratio here)?

[Ray]

Originally Posted by Clawhammer

Thanks Ray, your input has been really helpful across several threads where I am trying to determine the best way to water and feed my plants; balancing effort, efficacy, and cost for my conditions and indoor setup.

My goal here is to reduce effort and maintain efficacy by using only one fertilizer as I was previously using both a bloom booster for those in spike and a balanced fert for those in vegetative growth.

Are you advocating the best single use fertilizer would be something with a higher nitrogen content? Would you water a orchid in spike with 12-1-1 or 30-10-10 (I'm talking ratio here)?

As far as I can see, there is no reason to change formulas.

The idea behind a "bloom booster" was based upon the fact that folks were applying WAY too much nitrogen, and it was quashing blooming. The manufacturer added more phosphorus to effectively "dilute" the nitrogen level in the concentrate, which thereby reduced the N, "allowing" the plant to bloom. As such, it was meant to be applied well in advance of spiking. However, if you recognize that you should control your feeding of orchids
to only a small amount anyway, you're not likely to ever overdose the nitrogen.

I prefer the K-Lite formula, but truthfully, it's not critical, as fertilizers are WAY down the "Maslow's Hierarchy" of plant needs.

What is important is that your plants get a small, steady does of nitrogen, with adequate calcium and magnesium, which might come from your water supply. The rest of the nutrients are in very small demand and are stored by the plant to be used as needed.

[kvet]

The almighty internet fud suggests most plants "eat" at a 3-1-2 ratio (not talking about fertilizer here, let's say the medium has ample nutrients), what kind of ratio do orchids eat?

[Ray]

Originally Posted by kvet

The almighty internet fud suggests most plants "eat" at a 3-1-2 ratio (not talking about fertilizer here, let's say the medium has ample nutrients), what kind of ratio do orchids eat?

I don't think anyone knows for sure.

If you rely on tissue analysis, the rough breakdown is:

90% is water
9% is C, O, H (from air and water) and N
0.9% is Ca, Mg, P, K & S
0.09% is everything else

Carbon being about 50% of the total "dry" weight.

I am a bit skeptical of tissue analysis however, as what's in the plant doesn't necessarily mean it's what's required. Using myself as an analogy, if tissue analysis is truly indicative of "what the body needs", then I must need a lot of cholesterol!

Phosphorus and potassium are good examples among plants, as both are accumulated pretty significantly, whether needed or not. If I remember correctly, the degree of K accumulation is controlled by the concentration in the rhizosphere, while P is actively "snatched up" by the plant, gathering all it can, no matter what the concentration.

If you want to read an interesting article on the subject, Rick Lockwood had an article, What Do Orchids Eat, published in the AOS Orchids Magazine 3/2013.

[isurus79]

Excellent thread. Just wanna follow along.

[Orchid grower]

Originally Posted by Ray

I don't think anyone knows for sure.

If you rely on tissue analysis, the rough breakdown is:

90% is water
9% is C, O, H (from air and water) and N
0.9% is Ca, Mg, P, K & S
0.09% is everything else

Carbon being about 50% of the total "dry" weight.

I am a bit skeptical of tissue analysis however, as what's in the plant doesn't necessarily mean it's what's required. Using myself as an analogy, if tissue analysis is truly indicative of "what the body needs", then I must need a lot of cholesterol!

Phosphorus and potassium are good examples among plants, as both are accumulated pretty significantly, whether needed or not. If I remember correctly, the degree of K accumulation is controlled by the concentration in the rhizosphere, while P is actively "snatched up" by the plant, gathering all it can, no matter what the concentration.

If you want to read an interesting article on the subject, Rick Lockwood had an article, What Do Orchids Eat, published in the AOS Orchids Magazine 3/2013.

Hi Ray,
The article you linked was interesting. If I understood correctly long term use of potassium could have a negative effect on orchids?
So essentially Rick reduced the orchids potassium intake and increased Calcium and Magnesium. For someone who is using a balanced fertilizer, (in my case 20-10-20) if I were to reduce my normal dosage am I not also reducing the amount of nitrogen and phosphorus? Does the increase of calcium and Magnesium make up for the overall reduction of N-P-K?

Here is a quote from the article : "My reduced
potassium and increased calcium and mag-
nesium program was initially accomplished
by reducing the amount of MSU fertilizer
by half, and adding equal parts of calcium
nitrate and magnesium sulfate.This kept the
nitrogen and phosphorous levels constant
while drastically reducing potassium and
increasing both the calcium and magnesium."

But I dont understand how the nitrogen and phosphorus levels were kept constant? Unless I am misunderstanding what Rick was actually saying which is completely possible

Would appreciate thoughts and clarification!!

[sam1147]

Ray- I can see you are more then ready to go again into the K-lite saga as in Slippertalk ?