Do Paphs need limestone in their mix?

[My Green Pets]

The plant in question for me is a Paph Prime Child (rothschildianum x primulinum). According to the link, prim is limestone-loving and roth grows in highly metallic, ultra basic but low in calcium 'serpentine' soils (had to look that one up).

[NYCorchidman]

I have never used lime added to my mix and my paphs have been doing fine for years.

The books I read also says it is not necessary.

The reason why some people add lime to the mix for paphs is exactly because of what you mentioned.
Many paphiopedilum species grow on or near limestone, but their roots are also covered with moss or some kind of dead leaf debris of various kinds for moisture and possibly nutrition. These are mostly slightly acidic. While some paphs do grow in or near area where the soil pH is slightly basic, not all data are accurate as some are taken from "near" the habitat site.
All in all, for best growth, all plants with the exception of those that particularly need basic or acidic soil, grow best in slight acidic to neutral soil (or mix) because that is when the most ions are readily available for plants to uptake.

Remember, limestone does not desolve like crazy for plants to drink up nor does it change the pH considerably.
Given the fact that many paphs lie on top the rock or between crevice with moss or dead plant material in which their roots grow into, gives clue about how important it is to have well-draining mix for them to thrive.

Also, if you are concerned about calcium, magnesium or other chemicals possibly not available, consider this.
Unless you use rainwater or RO water, which is devoid of minerals, you don't have much to worry about. If you are still concerned, then use balanced fertilizer with mirco elements.

Most importantly, if your plants look healthy and grow well, and bloom regularly, all is well.

Bark and moss, what you have at hand is sufficient for your plant in my opinion.

Happy growing!

[My Green Pets]

Well thank you!

In the end, I potted up my Prime Child with bark, moss, and a couple handfuls of "marble nuggets" which I got at the big box store. Now we wait and see.

[DeaC]

Originally Posted by King_of_orchid_growing:)

Sandstone and granite are not alkaline in pH, they are acidic in pH. Limestone is alkaline in pH.

Certain Paphs appear to benefit from calcium supplementation or limestone in their potting mixes.

You can add some of the smaller limestone rocks into a mix with some medium grade bark. For some Paphs, it's as easy as that.

Would eggshell have any benefit?

[King_of_orchid_growing:)]

Originally Posted by DeaC

Would eggshell have any benefit?

Maybe if it was crushed into powder, idk.

[Hiester]

Originally Posted by DeaC

Would eggshell have any benefit?

I was wondering when someone would ask. Roy (orchid grower on YouTube) says his granny in Thailand always included a few crushed egg shells in her orchid potting mix, i.e. for any orchid she was potting up or repotting, so he does the same. Someplace else I read the shells should be cleaned of any membrane still adhering to them.

My mother didn't grow orchids, but she had a lot of houseplants. She always included a little bit of coffee grounds and crushed eggshells in her potting mixture for house plants.

[RJSquirrel]

I think all orchids and plants need calcium. How much and how to make it available to the plant without over salting the fertilizer or media with chlorides.

Most of the home methods of calcium enrichment are not very efficient and you cant gauge actually how much is leeching from the eggshells or the oyster shells or the rocks etc etc etc. its very safe but I feel not very effective.

A fertilizer such as the peters cal mag excel takes away all the guessing in most of the calcium magnesium orchid/paph questions.


when our city water has chlorine forced into it and you feed plants a lot of calcium in your feeding you end up with calcium chloride that falls out as a solid(salt) as it bonds with the chlorine from the water.

With magnesium which is also a mobile nutrient needed for orchids, magnesium chloride can be used for magnesium sulfate (Epsom salt) to help correct magnesium deficiency in plants. Use a smaller dose when using magnesium chloride compared to the recommended dose of magnesium sulfate .This is due to the chlorine in magnesium chloride, which can easily reach toxic levels if over-applied and/or applied too often.

So you see how factors are involved on what your plants might or might not be needing depending on your source of water and how heavy it is already with salts(chlorides )

[Manfred Busche]

What should a Paphiopedilum plant have done every year to be deemed 'doing fine for years' ?

Can the diligently caring grower expect one (1) new growth per year and also a flower spike
from an adult P. rothschildianum plant with 60 cms leaf span ?

[NYCorchidman]

It's up to the care you provide and the genes of the particular roth plant you have.
In general, multis grow like crazy once they past seedling stage. Flowering is a different issue.

Ok, this is rather irrelevant to the original posting.

Back to the egg shells, I always added egg shells to certain veggies and other plants that grow in the dirt.
You don't have to wash the egg shells because the membrane or whatever else is left on the inner surface of the egg shell will simply just rot out and add more nutrients to the plant in dirt.
For orchids in pot with porous mix, the left over on the egg shell won't necessarily harm the roots, but it can smell for a while, but will eventually wash out.
Crushing will have nearly zero effect unless it is crushed into fine powder.

Again, people who use tap water like me, there is plenty of calcium and other stuff in the water already. Use well balanced fertilizer with trace elements.
Adding lime stone won't hurt, but if you are to use the manufactured one that is designed to melt away rather quickly, it can only cause problem depending on how much is added.

So, again, good fertilizer and you can forget about any headache or guessing games.

I have even grown paphs with no fertilizer but just tap water for about one year. no harm done at all.

[Fairorchids]

Some 5-6 years ago lime stone (or crushed oyster shell) was a hot topic. Most growers have stopped using it though, as it appears to have been speculation rather than scientific study/documentation that drove this. Going back to about 1948, neither my dad nor I have ever used it, and we have grown a lot of Paphs.