# Application of calcium supplements for calciferous paphs?



## Marco (Sep 29, 2006)

If you use calcium supplements, how often do you put lime/oyster shell/egg shell etc..etc.. in your plants? And what do you use?


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## Heather (Sep 30, 2006)

Not often enough! 
I last did it a year ago.  
I use crushed oystershell. Clearly it is time to do re-apply!


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## likespaphs (Sep 30, 2006)

Heather said:


> Not often enough!
> I last did it a year ago.
> I use crushed oystershell. Clearly it is time to do re-apply!



i'm in the same boat as heather. oyster shell (ones i collected from the bike path and later used a mortar and pestle to crush...not recommended as it's tedious) not nearly often enough...


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## L I Jane (Sep 30, 2006)

About once a year & when I repot I dress the pot using crushed oyster shell fom the pet store for birds.


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## aquacorps (Sep 30, 2006)

Go to an Agway. they have calcium chips for chickens. picked up a fifty pound bag for around ten dollars.


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## Heather (Sep 30, 2006)

I wonder how often people who actually do it regularly do it. Once a month? Every 4 months? Once a year? Is there actually a recommendation?


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## Darin (Sep 30, 2006)

I try to do it every 3 months... but in reality, it gets done about every 6 as I forget.


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## gore42 (Sep 30, 2006)

I only do it every 6 months - 1 year. Generally, I use oyster as a top dressing, and once I notice that most of the small pieces are gone, I apply some more. If you use a Calcium enhanced fertilizer, it is probably not that important. I am skeptical about whether the amount of oyster I use as a top dressing has any affect on the pH of the medium anyway, considering the acidity of bark and fertilizer... I usually rely on Protekt to get my pH into the right range anyway, when fertilizing.

- Matt


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## silence882 (Sep 30, 2006)

I try to topdress the calcicolous paphs with oyster shell every month or two. I avoid doing it to the non-calcicolous paphs since some of their in situ media can be very acidic, pH 3-5.

When supplying calcium, oyster shell / lime / limestone mostly help maintain the pH of the medium. They're calcium carbonate (CaCO3), which is only slightly soluble in cold water. If you're looking to supplement the plants with extra calcium, you can add calcium nitrate (Ca(NO3)2) to your fertilizer. I add it along with epsom salts (magnesium sulfate) occasionally if the leaves on my multiflorals are looking a bit pale.

There was a small study published in Orchids about a year ago on the pH effects of adding lime to a bark-based mix for paphs. It showed that lime did help maintain the pH of the mix near neutral. Ever since I've tried to keep a healthy supply of oyster shell on hand.

--Stephen


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## gore42 (Sep 30, 2006)

Stephen,

You'll recall that for the article in Orchids, dolomite lime was used to add calcium and magnesium. Dolomite lime is significantly more reactive than oyster shell, and has to be applied more frequently. And in the end, if I'm not mistaken, the author concluded that all of the plants used in the test were healthy (including those without added lime). Also, he stated at one point that too much lime could cause problems, though I don't remember exactly what the effects were. 

- Matt


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## silence882 (Sep 30, 2006)

According to the article, in the experiment, Wang mixed in powdered dolomitic lime at various rates to the bark/perlite/sphag media before potting and didn't supplement it. After 14 months, he found that the media with 8-16 kg/m3 had a pH of 5.48-5.73 after starting at a pH of 6.18-6.25. The media without lime had a pH of 3.76 after starting at 4.17. The media with lime at 4 kg/m3 started at 6.05, but fell gradually to 3.95.

The lime upped the pH of the media when the plants were first potted and kept the pH in a reasonable range for 14 months.

The plants themselves at all concentrations used "had similar leafspan and leaf number," but "More plants with the highest lime rate produced flowers than those without lime." However, he, "did observe some plants with pale leaves at high lime rates as it was a concern of Larry M. Heuer in his 1977 article in the AOS Bulletin."

My only problem with the study was that it used Maudiae-type hybrids (Laser x Cherry Cider). The barbata species making up this hybrid's background generally aren't calcicolous and grow in acidic media. I'd like to see the study redone with calcicolous species or hybrids with mainly calcicolous species in their background.

--Stephen

source: Wang, Y. Special Report, How Lime and Fertility Affect a Hybrid Paphiopedilum. Orchids 74 (11):814-815, Nov; 2005.

p.s. for a list of calcicolous paphs:
http://www.slipperorchids.info/calcicolous.html


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## Rick (Sep 30, 2006)

I generally only add oyster shell when I repot since I use about 5-10% of the potting mix (calciolous species only) in oyter shell.

I use clear pots, and if it looks like the oyster shell is gone before I think I need to repot, then I'll top dress.

In response to the article that Stephen is refering to I put some oyster shell in distilled water overnight and then ran hardness and alkalinity at the lab. Although oyster shell is mostly calcium carbonate (and difficult to disolve at neutral pH), I definitely got a big pH jump with significant measurable hardness (ie disolved calcium). So I'd say its a good way to moderate pH and slow release calcium.


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## patrix (Dec 7, 2006)

If I use cal/mag should i still supplement?


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## NYEric (Dec 7, 2006)

You people are so funny. Oyster shells I pick up walking along the beach! And "AGWAY"! :rollhappy: Anyway, I need a new source for potting materials and supplies in the Northeast. Can anyone suggest one. Thanx


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## Shadow (Dec 7, 2006)

Does somebody know what the result will be if to add calcium supplements for non calciferous paphs?


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## Barbara (Dec 7, 2006)

Thank you, that was most informative. The link is just wonderful, since I have been wondering where I might find just such a list.
Going to the pet shop to get oyster shells real soon. 
Barb.


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## Heather (Dec 7, 2006)

NYEric said:


> You people are so funny. Oyster shells I pick up walking along the beach! And "AGWAY"! :rollhappy: Anyway, I need a new source for potting materials and supplies in the Northeast. Can anyone suggest one. Thanx



http://www.kkorchid.com/


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