Do you need CalMag supplementation with MSU?

[estación seca]

Fertilizer isn't really that important. If you use any 20-20-20 product with micronutrients, and dilute it to a reasonable nitrogen concentration, your plants will do fine.

[LadyOrchid]

Oh yes and about pH...my RO water with MSU will give me around 5.5 or 6. If I add little less than halp my tap water I have around 6.5 to 7 what I consider very good. If I add more than half my tap water I will have even more. Total ppm is around 130-150 which is also fine as it is less than recommended from Rain mix ;-)

And extra minerals such Calcium and Magnesium are added.

[Ray]

The pH of the applied solution has very little impact oin the plant. It's the pH within the medium that's important, and both the medium and plant affect that more than does the plant.

[LadyOrchid]

Thank you Ray sooo much! You are always so happy to help and teach... while I really like learn!!!

I don't use organic medium with my orchids, only with Cymbidiums.
My orchids are in semi-hydro or in clay with leca (mostly Cattleyas).

For now I really don't have issues and I follow your rule less is best. I really hope to find K-Lite in Europe in future. After all readings I wish that fertilizer so much ;-)))

Thanks guys so much!

[Ray]

I think you'd be surprised at just how much the plant influences the chemistry of the root zone.

I recall seeing early-morning pH levels as low as 3.5 in S/H plants only receiving RO water, but that changed drastically as the day progressed.

If you want to check it yourself, do a Google search for "pour-through method of pH testing".

[Orchid Whisperer]

Originally Posted by estación seca

Fertilizer isn't really that important. If you use any 20-20-20 product with micronutrients, and dilute it to a reasonable nitrogen concentration, your plants will do fine.

This is pretty much my philosophy with fertilizer. the N-P-K ratio does not even need to be exactly 20-20-20. There is a variety of fertilizers that have different N-P-K ratios, and many can be used for orchids. There have been many past discussions on Orchidboard regarding whether K-lite is a good fertilizer, or not. I prefer not to use it, and others will have different opinions.

What I look for in a commercial fertilizer:

1. Analysis of the fertilizer is disclosed (so that you know what you are providing to your plants)

2. Supplies each of the 3 macronutrients (N, P, and K), none omitted. Additional nutrients (such as Ca, Mg, and S) and micronutrients (small quantities of B, Fe, Mo, Cu, Mn, Ni, Zn, possibly others) are beneficial.

3. The form of nitrogen is, in my opinion, not too important (nitrate, ammonia, and urea are all fine)

4. Should be water soluble, no strong odor (important for plants indoors).

5. Well manufactured, uniform product.