Phal Bellina Yellow Spots

[Leafmite]

I like your set up! What a great way to grow orchids! Your temperatures sound good.

I found that with the MSU (for rainwater), I still wasn't getting enough Calcium for some of my orchids. I suffered some signs of Calcium deficiency after I switched to it and I had to begin adding additional Calcium. (I grow Angraecums and Cattleyas which tend to like quite a bit of Calcium). I use it for all of my plants and, a couple of months ago, I saw some signs of magnesium deficiency so I gave my plants a good dose of epsom salts. I think those are the only issues I have with what I am using. It might be the brand of MSU fertilizer I am using, too. No idea.

[Manu]

Yeah I really like my setup... I had to do something that looked good enough for my wife to let me set this up in the living room, she's quite happy with the result. It was a lot of work and in the end also somewhat expensive, but there is nothing like custom hand made things IMO. It's also really rewarding when you see the plants enjoying it and thriving (except for my Bellina, but the issues came before the setup). This morning I just noticed my haraella retrocalla with a bud about to open, that one never really did much until the lights were turned on, now full of roots, new spikes and a bud opening!!

Let me ask you, what is your pH like before you add fertilizer? Rain Water should be around 5.5 right? So your fertilizer acts as a pH+ at the same time I must assume?

How important is the pH? Am I causing trouble if around 6? I thought Orchids were acid loving plants? Ecuagenera even suggested I use only pure rain water for my few draculas... Should I get some pH+ to get it closer to 6.5-6.9 range?

I always overlooked the effect of fertilizer on the pH. I naively assumed that fertilizer specially formulated for Orchids made by a 'reputable' cie (correct me if I'm wrong about Dyna-Gro) would provide an acceptable pH when mixed to water that is good.

Seems as Dyna-Gro Orchid-Pro and Mag-Pro both act as a pH- seeing that my water drops from 6.8 to below 6.2...

Once more, to everyone who took the time to read and answer me I'm so thankful :-) I love this forum such a great resource and everyone is always so nice :-)

Originally Posted by Leafmite

I like your set up! What a great way to grow orchids! Your temperatures sound good.

I found that with the MSU (for rainwater), I still wasn't getting enough Calcium for some of my orchids. I suffered some signs of Calcium deficiency after I switched to it and I had to begin adding additional Calcium. (I grow Angraecums and Cattleyas which tend to like quite a bit of Calcium). I use it for all of my plants and, a couple of months ago, I saw some signs of magnesium deficiency so I gave my plants a good dose of epsom salts. I think those are the only issues I have with what I am using. It might be the brand of MSU fertilizer I am using, too. No idea.

[Sharon's Sheepdogs]

Most orchids grow best with a slightly acidic pH around their root zone. However, you really need to research the type of orchid you are growing & determine what their prefered pH is. I understand Paphiopedilums actually prefer a slightly alkaline pH.

The fertilizer must be water soluble within a specific pH range so that the roots can take the nutrients up. There are macro and micronutrients which are important for the orchid's growth. I fertilize my orchids in distilled water which, like R.O., does not contain minerals or has had the majority of them removed. For that reason, there is nothing in the water to act as a buffering agent so the addition of fertilizer can cause the pH to drop to very acidic conditions which are harmful to the orchid. When pH is too acidic, toxic amounts of the fertilizer can be taken up by the roots. When the pH is too alkaline (base), the fertilizer is no longer water soluble and is not available to the roots for uptake.

Over the years, I have seen recommendations of anywhere from 5.8 to 7.0 (acid to neutral) pH for growing orchids. It is my understanding that a pH level of 6.4 to 6.5 will allow the best nutrient uptake of the majority of macro & micronutrients. However, all substrates (I believe LECA is an exception) decay & become more acidic over time and I grow my Phals in sphagnum moss which is an acidic substrate. For that reason, I aim for a pH of 6.5 to 6.9 which is low acidity towards neutral. I have also read that some diseases become more prominent at lower pH levels. This has worked well for me growing Phals & Cattleyas under T5 fluorescent lighting indoors.

In the end you will need to begin periodic testing of your fertilizer solution after it has run through the substrate you are growing your orchids in. To start though, you should make sure the fertilizer going in is in an optimal pH range for the best nutrient uptake possible. After awhile, you'll find what works best for you.

I do use liquid MSU Fertilizer for pure water plus I add Humid Acid & Protekt to the mix. If you decide to switch to MSU let me know & I will tell you how much I was advised to use in the spring/summer and fall/winter. I do fertilize 'weakly' at each watering & flush with tap water twice a month. In the early spring. I will also add Cal Mag separately just to make sure my orchids are getting enough calcium & magnesium when their growth begins. I will only do this three times because I don't want them to receive too much.

I did find an article on the Venice Orchid Society located at: HOW YOUR WATER CAN AFFECT YOUR ORCHID – “PHood” – Venice Area Orchid Society. It stated that numerous white spots on your orchid leaves can also be caused by high alkalinity. Glad you ordered that pH meter. I think it will help you figure this out. Good luck!