Expanded clay balls (pellets)

ifraser25(z11 Brazil)October 23, 2010

I've had a lot of success recently with expanded clay and thought I would share. I have been using it mainly with Dendrobium and Cattleya but can see how it could easily be used as a substrate for (semi)terrestrials such as Zygopetalum, Paphs and Cymbidium. The principal advantage of expanded clay pellets is that they hold a lot of moisture but also dry out quickly. This combination of wet and dry is what a lot of orchids like. The balls themselves are quite absorbent but there is a lot of air space between them so there is little danger of overwatering. Also, the clay has a lot of nutrients esp. micronutrients like manganese, which is very helpful.

The main disadvantage is that when dry they are quite light in weight, which means there is danger of plants overbalancing if grown in pots. This can be overcome very simply, by putting a few heavy stones in the base of the pot or using clay pots. I am in my early stages with Zygos, Paphs and Cymbidiums. In addition to the clay I have added some crushed bark plus a little ordinary garden dirt (mostly fine clay), and in the case of the Paphs a few limestone chips. The mix looks good but only time will tell. If you give it a try do let us know.

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highjack(z6 KY)

I've been using it for three years now and would never go back to bark. I think you can grow anything in it as long as the water needs are met.

I've never heard or read any information regarding micronutrients in the pellets and was told you must fertilize since the media had none.


    Bookmark   October 23, 2010 at 7:45AM
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I know nothing about expanded clay so I googled and found a post (not here) that talks about the success from using semi-hydropics with this kind of clay balls. The poster explained "The semi-hydro pots are fairly basic. Polypropylene pots of various sizes with a pair of holes drilled about an inch up from the bottom to create a reservoir." I'm a little confused, does it mean no holes in the bottom of the pot? Only on the side? Wouldn't the water damage the roots?

I just got a Cattleya 2 weeks ago (and about to get another one) so I want to keep this in mind when it's time to repot.


    Bookmark   October 23, 2010 at 1:39PM
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I've been using this substrate for a couple of years and I'm pretty happy with my results. If the plant has a good root system when I move it over, it acclimates quickly and seems to love it.

To answer highjack's question about micronutrients and fertilizer, the micronutrients are just trace elements that are slowly released over time. You still need regular fertilizer and the micronutrients just help the plant with a little added nutrition that might be missing from the fertilizer and/or water. An analogy would be our food. We need protein, fats and carbs, but we also need milligram and microgram amounts of things like iron, zinc and cobalt.

To answer forapple's question about water damage, I frequently see the roots going down only so far and then they stop or change directions. If it's too wet, they grow away from the water. If you plant the orchid so the roots are in the water, they will rot.

Hope that helps,

Here is a link that might be useful: What's blooming in the greenhouse now.

    Bookmark   October 23, 2010 at 10:51PM
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Have you found an economical source online to purchase this product?

    Bookmark   October 24, 2010 at 5:59AM
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I've actually bought all of mine off eBay. If you shop carefully you can find some ok prices (like 50 liters for about $55). I had a seller I used to always buy from, but he stopped selling hydroton. Here's the best price I found on a large amount and I ordered it this weekend:


For what it's worth, if you loose a plant in hydroton, you can boil the hydroton and reuse it...you probably wouldn't want to do that with bark.


Here is a link that might be useful: What's blooming in the greenhouse now.

    Bookmark   October 24, 2010 at 6:54AM
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Don, thanks for the answer.

I just got two Oncidium yesterday, one is almost too big for the pot it came it and can't even stand on it own without tipping over. I wonder if it's time to repot and can I use the clay pellets with Oncidium?

    Bookmark   October 25, 2010 at 4:11PM
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I buy my media from hydroponics stores. I am sure they are cheaper than $55 and you don't have to pay postage. I have about 500 orchids and 90% are in semihydro. except for phals and cymbidums. My dends I grow in hanging baskets with just spagnum moss. I have grown them in semi-hydro and they do fine. I just like them in hanging baskets. I have had no luch with Phals I am using spagnum moss pots with lots of holes that I add in the pots so they get lots of air. I have tried cymbidiums in seimi=hydro and have not much success. I have gone back to the cymbidum mix and they are doing a lot better. I got one in flower now and a couple more spiking out.

    Bookmark   October 25, 2010 at 5:42PM
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Ron, thanks! I was hoping the clay pellets can be the one-for-all solution (at least for the ones I have) so I don't have to keep track with so many requirements for each orchid, I guess there is no such thing :)

    Bookmark   October 25, 2010 at 9:00PM
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forapple I think the semi-hydro is the best for overall use. However every now and then. I will get one where the plant just doesn't seem to like it. I will try that plant in plain bark. I lso have three locations where I grow. one is the greenhouse. if it doesn seem to like it I will move it to my solarium. If not there then to my hot tub room. Another thing to be aware of is location in the room. I have some cold corners in my solarium and I have some warm corners. Some areas of the room get lots of light and some less. I have a several cheap thermeters those that have the hydrometer. I just lay them next to my plants. You would be surprised how enviroment changes in different locations.

    Bookmark   October 26, 2010 at 12:34AM
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Thanks Ron, wow! you have so many orchids and great locations to grow them. Right now I only have two workable windowsills :)

I just bought an indoor/outdoor weather station a few days ago. I move the outdoor unit along with my two Vandas (in & out of the garage) and keep the indoor unit near my other orchids. I even got a light meter too. These are excellent tools/toys :)

I wanted to repot one of my Oncidiums (I think some kind of Zygopetalum) it didn't have a tag. I misread your post when you said it didn't work with your Cymbidium (the name sounds similar).

    Bookmark   October 26, 2010 at 2:49PM
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I hope I didn't mislead you the cymbidiums did seem to work for me in the semi-hydro. But I have talked to people who have excellent success with that method. Thats one thing about orchids and gardening in general. You will find that a lot on this forum. You say how you do things and the very next entry somebody says I don't do it that way. That is fine, What works for me might not work for you. So be prepared to try different things. Just watch your leaves and roots those are your indicators. (and off course flowering)

    Bookmark   October 26, 2010 at 3:01PM
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I bought some LECA (hydroton, to be more specific) at a local hydroponics store. It was $8 for a bag. I forgot how much the bag weighed. I can't check it right now, but it was enough to pot several orchids. I repotted a poor NOID paph in S/H. It was originally stuck in a tight wad of sphag, but it wasn't there long enough for the roots to rot. I think I rescued it just in time--the roots are good and it has 3 new growths. Its flower has lasted almost 2 months, even after the transfer to S/H. I also have a dendrobium and 2 laelias growing in S/H.

    Bookmark   October 26, 2010 at 4:59PM
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Thanks! No worries... I know there are so many variables that can change the outcome of each experiment. Like you said, I have to try and see which one works for me :)


    Bookmark   October 27, 2010 at 1:42PM
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How often to you water in S/H? Only when the reservoir is empty? Will the pellets stay moist until the water in the reservoir runs dry? How high (and how many) do you drill the holes?
Also, what kind of orchids are doing well with such a method?


    Bookmark   November 4, 2010 at 9:47PM
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albertan(Florida (10))

I have had a lot of success with aliflor and semi-hydro growing, particularly phals and catts. The original roots rot after transfering to hydro, and the new roots acclimate to the constant moisture and often grow down into reservor with no harm to them. I usually dump plant after 4 months in semihydro, remove rotted old roots and repot in same pellets after rinsing them. The constant weak fertilizing keeps plants lookin' good and blooming seasonally. I don't do denderobes this way because of their ungainly height and difficulty in firmly staking them. But I DO grow them in aliflor in clay pots, using ring supports for support and easy grooming.

    Bookmark   November 6, 2010 at 1:39AM
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albertan, can you show us your staked dens in aliflor and phals in semihydro? Thank you.


    Bookmark   November 6, 2010 at 10:12PM
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