Caution with MSU fertilizer!!!

[knthms5]

We began using a version of MSU fertilizer and our Orchids just quit growing or only very very slowly. Many of ours are in FWC if that matters but we knew something was wrong! Eventually a neighbor told me of her Orchid success and she had started some of hers in FWC at the same time. She mentioned she was using distilled water so I decided to change from tap to rain water. Within weeks roots started popping out everywhere, spikes on several, and the leaves were firming up and shiny again. I just today figured out why. Our bag of MSU was labeled for tap water, ro, and rainwater. There is no one formula for these types. One has calcium and magnesium added. My theory is that was the problem because before we started using the MSU we were seeing better growth across the board. In the picture of the larger bag that they took our two pound bag from it shows ro formula. I know that the ph of our ro is 6 versus the 7.8 of our tap but we had grown more successfully with tap water in the past. It was when we switched to MSU that everything stalled.

[SouthPark]

Originally Posted by knthms5

We began using a version of MSU fertilizer and our Orchids just quit growing or only very very slowly.

What concentration were you using? Eg. X gram into Y litre of water.

[Ray]

Let's not get carried away here. MSU fertilizer, whether it is the "Well Water" formula, meant for most water supplies that have reasonable levels of calcium and magnesium in them, and the "RO" formula for water supplies that don't, are very good, as is K-Lite, a derivative of the RO formula.

If your's was labeled to be for all, I'm going to guess it came from RepotMe.com, so blame them for mislabeling.

I agree with SouthPark that your concentration was likely the issue, as neither the chemistry of the product, nor the resulting pH would have that drastic of an impact.

[knthms5]

We are using it as described on bag, 1 teaspoon per gallon and continue to use it at that concentration but have changed to RO water and now all the growth in only 3 weeks.

[Ray]

Is that the 13%N formula? If so, one teaspoon per gallon is providing about 170-175 ppm N, which would be my recommendation for application once every two weeks for plants in traditional culture.

In full water culture, where the exposure is constant, I would use no more that 15%-20% of that.

I can pretty much guarantee - having first hand experience - that at your current feeding rate, the plant will likely grow great, but blooming will be severely curtailed.