Dolomitic Lime

[orcdfrk]

I've heard this from several growers regarding Paphs that they welcome this stuff every once in awhile as a top dressing. Not the powdered stuff but the stuff that is a bit coarser, almost like small perlite size. Does this encourage blooming or is it just beneficial? This is more a question for Ray but I'm hoping others have used this with good results.

[Mahon]

Here's my little bit of input... Lime is VERY good for Paphiopedilum (some naturally grow directly in this substrate), but there are many types of lime, and it's important to know what your lime does.

Lime contains Calcium and Magnesium, and is normally used to reduce and prevent the surrounding substrate from becoming acidic. But sometimes, certain limes can cause chlorosis in the plants. Locality is very important to know when purchasing lime. There should be more information and analysis on the many types of lime and their locations.

I would reccomend smaller pieces, not crushed lime. As for a top dressing, this may be good, but is even more benificial if it is mixed with the media. Lime is still great, but precautions need to be taken, such as the media you are mixing it with. Some bark substrates will cause chlrosis or necrosis. These bark substrates added with lime can increase the chance or affects of chlorosis or necrosis. I have some good Paph. media "recipes" with lime, if interested...

-Pat

[KEGinMichigan]

How about lime when growing in clay aggregate? I grow most if not all of my paphs in this semi-hydroponically. Within the next few weeks, I'm going to buy some of this.

Any advice?

Thanks,
K

[Ray]

Here's a smattering of comments:

Lime is primarily calcium carbonate. Dolomite or dolomitic lime is a variable calcium magnesium carbonate mineral.

As both Ca and Mg are needed for the plants, I would tend to think the dolomite is a more useful choice.

The solubility of these materials varies a bit with temperature, so the fact that some plants live on limestone outcroppings does not directly translate to our "captive" growing in different conditions. Also keep in mind that an acidic fertilizer solution will dissolve it more rapidly than does pure rainwater.

I would NOT add any to the s/h pot unless the particle size is the same as the medium. Actually, I don't bother at all, as the fertilizer I use contains all of the minerals needed anyway.

[KEGinMichigan]

Thanks, Ray. I use the MSU formulation. I think that has all the minerals needed too. I just haven't looked in awhile.

Kev

[weng]

I agree with Ray. Most growers find that Paphs do not require limestone or dolomite in their growing medium, but I had been growing mine in a dolomite mix as I only use rainwater.

My own observations on deflasking several species into pure Seramis (very small terracotta granules) and my dolomite mix showed no difference in growth, so I only use Seramis now.

Many fertilisers do not contain calcium as they are formulated on the assumption that you are using tap water. So watch out for that.

Weng

[orcdfrk]

Thanks to everyone for weighing in on this. It was just what I had heard.