how does one prepare macadamia shells as an orchid potting medium

[Edward Brookes]

Hello, while I am far from being a newbie with orchids, I am passionate about them & eager to learn anything anybody can offer. I have recently been able to buy macadamia shells, but can find no information on the best way to prepare them as orchid potting medium - soaking, cleaning, additives, any information which would help me prepare the shells to best advantage for my orchids (a VERY mixed collection, outdoors in a subtropical climate) I would like to hear from anybody who has experience with this medium.

[Silje]

I'm using macadamia shells in additional to perlite and/or fir bark for a lot of mine. Honestly, I don't do anything except rinse them. I don't sterilize them and I don't soak them in fertilizer or fungicides or anything.

They provide a lot of air pockets, but one disadvantage as far I see it, is that some of them also become like small 'bowls' where the water gathers if they lie in the right (or rather, wrong) position.

They last long and my experience is that they remain relatively intact much longer than my bark mix.

In terms of whether they contain anything that one should be aware or cautious with, I've got no idea. If they are acidic or whatever...no idea.

I'm also interested in hearing other people's experience with them.

[Edward Brookes]

Thank you Silje, I have tried mixing the macadamia with bark but we cannot get suitable bark here - the available type breaks down very quickly. To beat the little bowl problem, I've been crushing the shells & also using terra cotta pots with holes in their sides - they dry out fast so the "Bowls are not a problem so far. The orchid roots seem to like the shells, grow down into them with no browning off of the tips or skimming over the surface & out over the edge of the pot. I'm using seaweed & fish emulsion fertilizers to stimulate roots, with inorganic macro & micro nutrients, alternating the types. All heavily diluted (about 1/4 strength) as foliar feed misted over the plants & pots. I add broken up styrene to the shells.

[No-Pro-mwa]

sorry I have never heard of using macadamia nuts as a potting medium. I just wanted to welcome you to the board.

[Edward Brookes]

Thank you, No-Pro-Mwa, for the welcome - much appreciated! The shells of macadamia nuts are quite widely used,so I am told,but are new to me. they are very hard and durable as a potting medium, & so far my orchids seem to grow very willingly into the shells. They are a waste by product,& thus very inexpesive. When I buy them they are already broken up by the shelling process, but many pieces are bowl shaped & prone to hold water. This could cause rotting for the orchid roots, & so I crush them further & add styrene beads & chunks to further open the mix. We cannot get good quality pine bark here, & I have found coco husk to be a disaster under my conditions. Hopefully the macadamia shells will fit the bill.

[Silje]

Originally Posted by Edward Brookes

Thank you, No-Pro-Mwa, for the welcome - much appreciated! The shells of macadamia nuts are quite widely used,so I am told,but are new to me. they are very hard and durable as a potting medium, & so far my orchids seem to grow very willingly into the shells. They are a waste by product,& thus very inexpesive. When I buy them they are already broken up by the shelling process, but many pieces are bowl shaped & prone to hold water. This could cause rotting for the orchid roots, & so I crush them further & add styrene beads & chunks to further open the mix. We cannot get good quality pine bark here, & I have found coco husk to be a disaster under my conditions. Hopefully the macadamia shells will fit the bill.

Where do you get coco husk, Edward? Because that is actually one of my favorites, but I'm unable to get it here in Nam and have been considering buying it from SA. The larger sized pieces. Peat stuff is lethal. I'm about to re-pot a lot of phals and I think I will try with more macadamia shells. Breaking them into smaller pieces is a good idea. I've only used them as they come in the bag.

I'm using bark from Barks unlimited and although it's not fantastic quality, the medium sized chips works pretty well for phals, I'd say.

[Edward Brookes]

Hello, Silje, if only you were nearer, I have some bales of coco husk that I would sell to you with pleasure, & at the old price! Grovida are imoprting it, VERY variable quality. To crush the macadamia, I put it into a piece of shade cloth, fold it over & tuck in the edges & then hammer away at the bigger pieces. You need the shade cloth envelope or the chunks fly about like missiles from a rocket launcher. Grovida probably have a web site you could google.

[OCRC_Dir_China]

I have used peanut shells, sunflower seed shells, and pea to small marble size gravel.
Not salted shells, just raw which is easily found in China. As for coconut husk I have bought coconuts and striped the fibers off. But I do recommend giving them a good soaking and wash for green skin coconuts. And let them dry for a good long period before using.

[Edward Brookes]

Hello, OCRC, thanks for the insight. I tried a few plants on whole coconuts as they are sold here, outer peel removed, but with a lot of husk intact. I tied the orchids onto them, & they grew very well & attracted lots of attention from friends who saw them in flower. The husks became full of fungal growth & the orchid roots rotted, so I gave up on that idea. Fungus is a real pest here, we can get rain day & night for a week at a time, so the husk stays wet. Algae forms on the surface & overall I find the husk to be unsuitable for me.If I were able to let it dry with controlled watering, I'm sure it would be good. My plants are mostly outdoors under shade cloth, so the weather is the boss.

[OCRC_Dir_China]

Did you grow them in the cup side of the shell or on the dome side of the shell? I lived in many Asian countries that have long periods of monsoon rains. I always had to keep a fan going and hold back the water.