Shultz orchid fertilizer

[Ray]

Hopefully answering both Helen and Mark...

Fertilizer formulas are expressed in weight percent elemental nitrogen (N), phosphorus as P2O5, and potassium as K20. From a label perspective, the form of the nitrogen is irrelevant (It's not to your plants, but that's a whole other discussion).

The Shultz stuff is 19% N by weight, or 190 mg/g of fertilizer. A milligram is a thousandth of a gram, so a mg/L (0.001/1000) is a part-per-million (ppm). So, if you added one gram of fertilizer to one liter of water, your nitrogen concentration would be 190 ppm.

That would mean, of course, that if you were foolish enough to accept my 125 ppm recommendation, you'd need (125/190) x 2.5 = 1.65 g of fertilizer in 2.5L of water.

With US measures, it's pretty easy - divide 10 by the percent N to get teaspoons per gallon.

[Helen]

Ray, I guess we are limited to space...you probably noticed you got cut off. I'm very interested in your final summation!

[Helen]

Ray, I just zipped over to your website. MY! what great info on fertilizing...I used your handy calculator so now I know much more than before!
Just to clarify, if I were going to fertilize weekly or every other week, I would still use the same formula? Is this considered 'weekly weakly'?
Thanks again

[Ray]

Naah. I wasn't cut off, I just went back to edit something and forgot that phrase was still there! (I'll go fix it!)

However, I didn't answer the MSU question: Dr. Bill Argo, a plant nutrition expert working for Blackmore Co. went back to his alma mater, Michigan State University, and developed an orchid fertilizer formula intended to be used at every watering. In the process of doing so, they also debunked the concept of high phosphorus as a "bloom booster", and confirmed the need for both calcium and magnesium. Formulas based upon their work have gained the generic term "MSU Fertilizer". The original is sold under the GreenCare Orchid Special brand name.

As far as using a 125 ppm N solution every week or every other week, using fresh water in between, I would view that as a starvation diet. Think of it in terms of how much food you're giving your plants, not how often they eat.

Let's assume you water twice a week in the summer months, and when you do water, the plants actually only absorb 10% of the fertilizer added. (It's actually quite variable and no doubt a lot less, but that makes simple math for the example.) Let's also assume the plant needs 0.5 grams of N for a growth to mature and bloom in a season (that's the number for poinsettia cuttings, but it's another convenient figure to use here).

That means that the plant is taking up 12.5 mg of N at each watering, and the plant will need 500/12.5 = 40 waterings, or 20 weeks to mature.

Now consider feeding at that same concentration, but only one time out of four waterings, so the plant now needs 80 weeks - more than a year and a half - to get the same level of nutrition.

My guess is that in the second scenario, the plant will actually languish terribly, as there's more to this that "just" nutrition. In the middle of a warm, sunny summer, a plant may be in the peak of its growth cycle, so thats when it needs its food. In the 20-week scenario, it's getting what it needs, when it needs it. In the 80 week scenario, it gets meager nutrition when it needs it and more when it doesn't, so it's wasted.

Now then, let's assume you buy all of this and have decided to feed a stronger solution, but still want to periodically flush with plain water. One approach - still keeping the total amount of food constant - is to feed at 250 ppm N every other watering, alternating with plain water. Personally, I'd go with a 3:1 ratio, feeding at 4/3 x 125 = 167 ppm N three waterings, then water only for the 4th. (The only trouble with that is remembering which number this watering is. That's why I feed at 125 ppm at every watering...what's to remember?)

[Helen]

Thanks Ray! It's extremely nice of you to take time to explain this to me in detail. I REALLY appreciate it. I'm going to go with your 125 ppm rule. It makes a lot of sense to me!
One more quick question:
So, you never worry about the Phosphate or potash or micronutrients at this point, only the N ??

[Ray]

Originally Posted by Helen

One more quick question:
So, you never worry about the Phosphate or potash or micronutrients at this point, only the N ??

Nope. All of the other elements are extremely important. The thing about it is that you should get a fertilizer formula that is complete with all of the nutrients, and assuming they are proportioned corrctly for your plants, you can merely contol the concentration using the nitrogen, and the rest will follow.

[Helen]

Excellent, thanks again!

[Helen]

This message is for Ray, who said:
"the MSU question: Dr. Bill Argo, a plant nutrition expert working for Blackmore Co. went back to his alma mater, Michigan State University, and developed an orchid fertilizer formula intended to be used at every watering. In the process of doing so, they also debunked the concept of high phosphorus as a "bloom booster", and confirmed the need for both calcium and magnesium. Formulas based upon their work have gained the generic term "MSU Fertilizer". The original is sold under the GreenCare Orchid Special brand name."

Ray, I actually bought the Schultz because I wanted a bloom booster (19-31-17). So basically, if this theory is correct, I didn't need to buy the one with high phos. I could have gone with a 20-20-20?
I guess I should ask you what YOU think the best combination is all around. Or, do we still have to switch back and forth depending on where the plant is in it's cycle? I really appreciate your assistance on this.

[Ray]

When you start thinking I'm the "expert", you're in BIG trouble, Helen.

I have no idea what the "right" formulation is, but I'm confident it varies from plant to plant. I have been very pleased with the growth and flowering of my general collection of plants using Dyna-Gro "Grow" formula and the Greencare MSU stuff, which is what I use exclusively these days.

While it is an important nutrient, plants actually use very little phosphorus. What Bill found was that excessive nitrogen is a "bloom quasher", not that high phosphorus being a "booster". The reason you see a lot of phosphorus in so-called "bloom boosters" is that inexpensive, phosphorus-containing minerals are added to an otherwise high nitrogen formula to dilute the nitrogen, rather than to specifically increase the phosphorus.

I do not feel it's necessary to switch fertilizer formulas periodically, as long as it's complete. Instead, it's probably more important to think about the amount of food provided. For example, I have used the MSU formula for RO exclusively and at every watering for 4 years, as of this month. The plants get the 125 ppm N each time, but the frequency varies with the season, meaning they're getting a lot of food in the summer, and little in the winter. Some plants won't bloom at all if you feed them in the fall and winter.

[Helen]

Ray, I just needed you to clarify your statement "but the frequency varies with the season". Do you mean you don't feed them at all during the fall/winter months, or just cut back somewhat? Is this when they get a rest? Thanks.