Which paphs need calcium, and how much does each species need?

[gonewild]

Egg shells would dissolve so fast in the mix their benefit would be too short lived. The idea of top dressing is so you can see when the material is gone and add more.

 

[DavidH]

I use an MSU based fertilizer for the west coast developed jointly by Fred Clarke of Sunset Valley Orchids and the folks at MSU. After reading Bob's article on supplemental calcium, I put crushed oyster shell from a local feed store on half my armeniacums and micranthums and left the other half without (approx 30 plants with, 30 plants without). After 6 months, the majority of plants with oyster shell dressing had 1-3 stolens growing up through the oyster shell whereas I had almost no stolen growth on the plants without. It's possible to argue that the oyster shell top dressing kept the potting media more moist versus adding any additional calcium.

The fertilizer rate I use is measured at 50 ppm Nitrogen with an EC of 0.39, and PPM of around 280-300 using RO water at 17 ppm. PH runs around 6.4 (summer) - 7.0 (winter). I've noticed the local water supply PH is higher in the winter months versus the summer months (7.4 summer, 8.0 winter).

Based on my personal experience, I plan on adding oyster shell top dressing to the majority of my paphs. As Bob mentioned, it can't really hurt. After reading his articles, I've also recently started adding supplemental epsom salts, with no other additives, when watering.

The bottom line with all orchid growing is that while all plants have basic requirements, each person has unique growing conditions that may result in slight to significant differences in potting media, fertilization rates (within a narrow margin), watering schedule, etc.

Personally, I like experimenting. After all, plants die...get over it.

-Dave
p.s. and if get get over 30% of my armeniacums and micranthums to bloom next year, I'm going to throw a party!!!

 

[gonewild]

I use an MSU based fertilizer for the west coast developed jointly by Fred Clarke of Sunset Valley Orchids and the folks at MSU.

How is this MSU formula different from others?
What is the NPK ratio?
% of Ca and Mg?
Who sells it?

After reading Bob's article on supplemental calcium, I put crushed oyster shell from a local feed store on half my armeniacums and micranthums and left the other half without (approx 30 plants with, 30 plants without). After 6 months, the majority of plants with oyster shell dressing had 1-3 stolens growing up through the oyster shell whereas I had almost no stolen growth on the plants without. It's possible to argue that the oyster shell top dressing kept the potting media more moist versus adding any additional calcium.

Great experiment.
What type of media are the plants growing in?
How often do you water?

The fertilizer rate I use is measured at 50 ppm Nitrogen with an EC of 0.39, and PPM of around 280-300 using RO water at 17 ppm. PH runs around 6.4 (summer) - 7.0 (winter). I've noticed the local water supply PH is higher in the winter months versus the summer months (7.4 summer, 8.0 winter).

How often do you apply fertilizer?

 

[gonewild]

Last week I gave our plants an extra dose of Epsom salts based on Bob's recommendation to see what happens. The first of next month we'll see if it made a difference. :drool:

 

[ScottMcC]

this discussion has me wondering about water hardness. after all, calcium and magnesium are the two main culprits in making water hard, and many orchid growers use ro water. so...if you were to just use tap water, would you still need supplemental calcium?

 

[gonewild]

this discussion has me wondering about water hardness. after all, calcium and magnesium are the two main culprits in making water hard, and many orchid growers use ro water. so...if you were to just use tap water, would you still need supplemental calcium?

That would of course depend on how much calcium your water contains.

 

[IdahoOrchid]

That would of course depend on how much calcium your water contains.

Would it not depend on what form it is in as well?

 

[DavidH]

How is this MSU formula different from others?
What is the NPK ratio?
% of Ca and Mg? Who sells it?

Good question. The info on the bag has rubbed off, but I have a new 50 lb bag on order and should arrive later this week so I can answer this question. Or, call Fred and he can answer since he developed it with the MSU folks. Also, a correction...the correct EC number is .40 not .39

great experiment.
What type of media are the plants growing in?
How often do you water?

The plants are growing in either a pumice/coir/perlite mix, or Aussie Gold mix, but I'm switching everything over to Antec's CHC mix due to the Aussie mix staying a little too wet and not enough airflow into the roots. I water 1-2 times a week in winter, 3-4 times a week in summer.

How often do you apply fertilizer?

It used to be every watering. However in the last two months it was every other watering due to a new tank and water pump installation. I'm switching back to every watering once I redesign my injection system due to the new pump and water tank I now have.

 

[gonewild]

Would it not depend on what form it is in as well?

Yes and no. It really depends on a lot of elements in the water. Most water does not have enough calcium to supply the plants with all they need.
To really know for sure you need to see a water analysis and interpret the total balance of all the minerals it contains.

A problem with using a water source high in calcium and magnesium will be that it is likely also high in total salts (PPM, TDS). When your water is already high in salts it makes it difficult to add enough "fertilizer" elements to your irrigation water without the total salt concentration getting to high for the health of the plants.

The big benefit with RO water is you don't need a water analysis to determine what nutrients you should add. You know you need to add everything the plant requires. And it is easy to determine what to add.

 

[Bob Wellenstein]

Many areas of the US have more than enough Calcium in the tap water to meet the needs of Paphs (and please remember that the point of top dressing certain species is likely pH control, not need for extra Calcium). I do not believe you will find sufficient Magnesium to be as widespread. Calcium in the water supply is generally from Calcium Carbonate, insoluble in pure water but soluble in the presence of acid resulting in Calcium and bicarbonate ions in the water. The problem is, when the water is removed by the plants or via evaporation, the excess precipitates out as insoluble Calcium Carbonate. When you use water free of Calcium Carbonate such as rain water or RO water, and add the appropriate amount of Calcium in a highly soluble form such as nitrate, any that precipitates out will be very effectively flushed with the next watering. This and a lot more is explained in the various articles at http://ladyslipper.com . They were written almost ten years ago, updated as new information is needed for clarification, to save the time from repeatedly trying to answer these questions.

 

[Bob Wellenstein]

Sorry if that sounds grumpy, but I am this morning!

 

[Bob Wellenstein]

When I used to go out and give talks I can't tell you the number of times I would have people come up and say "I have heard brachys are hard to grow, but I do great with them, but I can't grow Maudiae types". I would talk to these folks and inevitably they had hard water. The opposite was also true, folks who did great with not only Maudiaes but mastersianum and similar species, but couldn't keep a bellatulum alive for more than a year, and they almost always either used rain water or had naturally pure water sources. Aside from just Paphs, it also became obvious that if you found an excellent orchid grower who didn't seem to have a clue as to why they did so well, you had found someone with naturally excellent water. Water, with whatever is needed in the form of minerals for the plant, and in the form of good humidity, seem to be one very important key in what separates growing Paphs from growing really healthy, happy Paphs.

 

[gonewild]

There is a maximum desirable calcium level. At high levels calcium will interfere with the uptake of other nutrients. This is especially true of the micro nutrients. Adding calcium to raise the pH may be good for plants that naturally need a high pH but it also may inhibit the growth of those plants that don't.

To much empathies is being put on isolated parts of the nutrient requirements of plants. Adding excess of one nutrient can and will cause a deficiency of another and vice versa. The ratio balance between nutrients is very important. That is why MSU formulas work so well, they are based on the balance of the whole contents.

 

[Rick]

There is a maximum desirable calcium level. At high levels calcium will interfere with the uptake of other nutrients. This is especially true of the micro nutrients. Adding calcium to raise the pH may be good for plants that naturally need a high pH but it also may inhibit the growth of those plants that don't.

To much empathies is being put on isolated parts of the nutrient requirements of plants. Adding excess of one nutrient can and will cause a deficiency of another and vice versa. The ratio balance between nutrients is very important. That is why MSU formulas work so well, they are based on the balance of the whole contents.

Calcium does not raise pH. The alkalinity from calcium salts such as Lime (calcium hydoxide) or the calcium carbonate in oyster shell will raise pH, but calcium chloride, sulfate, or nitrate. are pH neutral salts.

 

[IdahoOrchid]

Can anyone tell me about Dical and Calcite? I have access to these at work.

 

[gonewild]

Can anyone tell me about Dical and Calcite? I have access to these at work.

I think both are pretty much insoluble in water and would not be much good for your plants. Dical is very high in phosphorous and would throw nutrient balances off.

What are they used for in your work?