How much MSU fertilizer to use (Repotme)

[glitchathon]

I got some MSU Fertilizer from Green Barn Orchid which is the same as the one that Repotme sells. It advises 1 ounce per gallon of water which equals 2 tablespoons.

Is it best to go with the recommended dosage or go a little less? Also any advantage of getting granular vs liquid versions? I went liquid this time.

This would be for my Phals and a new Cattleya I got.

Thanks.

[DelawareJim]

It depends on how often you plan to fertilize. As a horticulturist I was taught "Feed weakly, weekly" Which is generally considered to be about 1/4 label recommendation.

I use MSU for pure water in distilled or R/O water at 125 ppm N per gallon, which works out to about 3/4teaspoon per gallon at every watering.

Ray's MSU label for pure label

Or if I use MSU formulated for well water I still shoot for 125 ppm N per gallon at every watering.

Ray's MSU label for well water

Cheers.
Jim

[Ray]

Divide 10 by the %N on the label - the result is teaspoons per gallon for 125 ppm N. (13/%N=ml/L)

[LuizaG]

Hi

I'm hoping Jim and Ray can help me too.

I have Orchid focus Grow 2.2 1.2 2.1 for my recovering Phalaenopsis with only 2 roots in small pot that needs watering every 3 days.

and
Orchid focus Bloom 1.8 2.4 2.6 for my in bloom healthy (hopefully) phalaenopsis in 12 cm pot that needs watering no earlier than 2 - 3 weeks.

Please help me figure out how to use these fertlizers weakly.

Many thanks
Luiza

[DelawareJim]

Luiza;

We don't have Orchid focus brand here in the States, but I'm assuming the 3 numbers you're providing at the percentages of N-P-K; so Grow has 2.2 percent N, 1.2 percent P, and 2.1 percent K.

Using Ray's calculation for the Orchid Focus Grow, 10 divided by 2.2 = 4.55 teaspoons per US gallon to yield 125 ppm N. I don't remember what the US-imperial gallon conversion is.

From there, I let the plant tell me what it needs after using it for awhile. If the plant looks a little pale or under nourished, I might bump it up to 5 teaspoons per gallon. If growth looks too leggy or the plant looks a little burnt from over fertilizing, I'd scale it back to 4 teaspoons.

Cheers.
Jim

[LuizaG]

Thanks Jim

Yes, the numbers I provided are the N-P-K.
1 Galon is 3.78 liters.

I am surprised to see that the label recommends the equivalent of 1.89 teaspoons per gallon and acordind to Ray's calculation it should 4.55.

I was actually thinking to use 1/4 or 1/2 of the recommended (on the botle) concentration for every watering and flush with clean water every 2 -3 waterings. Now it looks like that is too little...

[camille1585]

I'm also using Orchid Focus Grow on my orchids lately, and watering weakly weakly at 125ppm N. I usually use fertilizer 3 out of 4 waterings. That comes out to 4.3 teaspoons per US gallon, or 5.6ml per liter, which is the same as when you calculate it with the %N/10.

[DelawareJim]

Luiza;

You seem to be over analysing this a wee bit. The concentration doesn't have to be spot on.

Plants are pretty forgiving. Start out with what Camille recommends and then as you get more experience you can tweak it if you want.

Cheers.
Jim

[glitchathon]

Thanks for the advice guys. I did a bit of calculation and figured out that the MSU label recommendation is close to ideal, though I will use just a tad less.

[LuizaG]

Hi Jim and Camille

Thanks for all your help. I finally understood how that calculator works and what I should be aiming for when I fertilise. And I finally know what "weak" means.

This morning I watered and fertilised both my phals with 100 PPM N (if they are ok with that will increase next time). I used the Bloom one for the phal with flowers and the Grow one for the small recovering phal with one root.

Also thanks to glitchathon as because of your thread I had the ocasion to find out the information I needed.

Luiza