Fertilizer composition question

[xiphius]

Hello all,

I have a quick question about the composition of MSU RO fertilizer. I have been using it for years now, but never really looked much past the NPK values before. Last night, I was looking more in depth at its composition in thinking about tweaking my regiment and realized that it does not seem to contain any source of sulfur?

This seems odd to me since my limited knowledge of plant nutrition leads me to believe that sulfur is very important as a nutrient (so much so that it is often clumped in with macronutrients). Is sulfur not as important for orchid growth as it is in other plants? Or is it assumed that the plant is getting enough sulfur through some secondary source like decomposition of the bark or something?

As one final question, do others on here that use MSU RO supplement sulfur some other way (if so, how? and how frequently?).

Sorry, I know I said that would be a quick question and it turned into more like 5 questions, but any advice or insight would be appreciated! Thanks in advance!

[Orchid Whisperer]

Sulfur is present in a lot of organic materials (plant matter, bird droppings, etc.) and is probably supplied to wild plants from those sources. You aare correct, it is an essential nutrient.

It is easily supplied through nutritional supplements that are sulfates, such as Epsom salts (which also provide Mg) or gypsum (also provides Ca). Dissolve up to a teaspoon of each in a gallon of water, add a cup per gallon of this solution when you water. Like other fertilizers, a weekly pure water flush is important.

[Ray]

Several of the ingredients in the formula are blended as sulfates, so there ought to be plenty...

[xiphius]

Originally Posted by Ray

Several of the ingredients in the formula are blended as sulfates, so there ought to be plenty...

Thanks Ray! Gotcha. That makes sense. I didn't look at the actual chemicals blended, just the overall percentages for macro and micro nutrients. For some reason, they don't bother to list sulfur.