The dosage I use is 1 tsp per gallon. As I can't be bothered to calculate what it is in metric, nor bother with weighing the stuff, I just dump 1 tsp in 4L of water.
The only orchid that gets the stuff on a regular basis is my Cym. No matter how much light it gets it will not bloom if I don't supplement it with magnesium. So the cym gets salts every 2-3 waterings most of the year. I have yet to use it on all the other orchids, but after seeing the water quality report of my area, I probably should. Our water is very soft.
Since Epsom salts are so very hard to find in Europe and quite expensive, I bought a carton in the US last time I went.

I know those is an old thread but just wanted to add that my alba has very pale leaves and the nursery said that was normal for the alba :dunno:

My semi alba is also a light green. But not yellowy green. That reminds me, I watered my green-yellow Phal pallens twice with epsom salts, and the result is amazing. The leaves are now a nice light green AND the plant suddenly started growing roots and a leaf, both of which it had not done at all since getting it a year ago. So I conclude that it must have had an Mg deficiency...

thanks Ill be doing this next watreing.

I might try Epsom salt. The equestris is growing a spike at the moment (it's about 2.5 inches long right now). So I will get to confirm soon if it is an alba or just a nutrient deficiency. So far I think I am seeing a bit of pink tinge on the tip of a tiny bud. I am leaning towards nutrition problems.

Here is a current picture of the spike.

Attachment 70663

I am seeing a lot of pink on the bud now, so I am assuming it will turn out normal color. I am starting to think either the plant got too much sun at the nursery before I got it or it is deficient on micro-nutrients. That can be adjusted :)
Either way, I am excited for the spike and can't wait until it opens. :biggrin:

Look forward to seeing your blooms!

Nastia, I also got P. equestris from Oak Hill around the same time. Mine is (unfortunately) var rose x var. aurea. This wasn't described in their web page, and I don't like hybrids or inter-variety crosses. Oh well... That's great yours is already spiking!

Mine has the similar color of leaves to yours, which is quite different from another specimen I have. It is not as pale as P. hieroglyphitica or P. pallens. P. equestris appear to have some variation in leaf morphologies: short vs long leaves, and difference in green color. The following page is not translated to English yet, but check the photos about half way down:
Equestris
This site is wonderful for pure species lovers who admire natural variation than people who like to "improve" species or create "beautiful/weird" hybrids.

Camille, according to the same site, P. pallens prefers higher light and temp. than most Phal species (there is English version of this info there). It could have been Mg def., but the recent growth could also be partly due to higher light of summer time, couldn't it?

Hi Naoki,
Sorry to hear you got something other than what you expected from Oak Hill Gardens. Mine has a generic "Phal equestris" tag without varietal info. However, I wouldn't rule out the possibility that I got the same plant as you since you are describing similar plant. We should definitely compare flowers together when they bloom.
Thanks for the link. It is an interesting comparison of different types of equestris.

No, I don't think it's that. Summer? What summer? It's been nasty chilly rainy weather most of the time.