OrchidSafari
Diatomite
Moderator: Joe DiDomenico
Wednesday Jan 22, 2003

Copyright OrchidSafari and Joe Di Domenico 2003
Opinions are those of the individuals only. Any changes to your growing methods should be carried out on a few 'expendable' plants prior to comitting your whole collection to it.

N_Calif_Kathy
Hi All,
Diatomite first got my attention when someone on the AOS Forum mentioned that the catts he bought from H&R were 3 times bigger in the potting material that H&R used versus his usual potting material. This person usually repots new purchases, and 'just didn't get around' to repotting those few seedlings.

That claim lead to me searching around the web for H&R's potting method and eventually led to me setting up this discussion with Mr. DiDomenico.

Please read Maidenwell USA Diatomite's homepage http://www.diatomiteusa.com and http://www.diatomiteusa.com/pitd.htm prior to Wednesday's meeting so we can all be aware of the product. Our Australian friends may know the product under a different name.

In Australia the company is called Maidenwell and has its homepage at http://www.maidenwell.com Buried somewhere on that page is a testimonial from H&R about their test trials with Diatomite. I have a .pdf link which may or may not work for you. But - hey - I tried. http://www.maidenwell.com/documents/technicalInformation/MDAQuality/Product.pdf
Buried elsewhere, either on the Maidenwell page or the Diatomite page is the potting recipe H&R used in its trials. So you can check it out for yourselves and see if it makes sense, according to what you know about potting.

H&R says they use it for their 'plugs'. Many other Hawaiians are using it now too, according to Leonard Gines, who recently spoke at our society.

If you are looking for a non-commercial source for diatomite information, try Harvey Brenneise's page: http://www.msu.edu/user/harveyb/orchid.htm Its about 1/2 way down the page.

I'm interested in knowing if it would be good for many of my smaller plants in 2 inch pots or for pleurothallids that I have had difficulty growing up.

And just so you don't think I'm bringing Joe on just to advertise his product I'll want to ask about silica and its effect on orchids, as well as diatoms - fresh water ones?? - I've never heard of any such a thing, but I'm willing to be convinced.

Additionally I thought that I would include a couple of emails that Janette Harris sent me. Bob Wellenstein of Antec Labs has been looking into Diatomite too. These exerpts are from Antec Lab's email list:

"Hi Folks,

About two years ago or so we imported 4 40 liter bags of a potting medium from Australia called Maidenwell Diatomite. H&R Orchids in Hawaii are the pioneers in the US with this medium, starting experiments some three years or more ago and switching over to using it as a 40 to 50% component of their growing mix. Our early results were excellent with Paphs and Phrags. We were especially pleased with how our Phrag besseaes responded when placed in pure diatomite and set in a tray with about 3/4" of water (holes drilled into the tray prevented further water accumulation, and allowed excess water to drain after irrigation). The pure diatomite has tremendous wicking action, and water can continually evaporate of the top when used this way, keeping the root zone of the plants cool even on very hot summer days. The besseaes, which suffered from excess heat during the summer and basically stopped growing (although they did much better with CHC than bark) took off and put on tremendous growth right through the heat of summer. We also have several types of besseae hybrids growing this way and doing well. It does seem to retain more moisture than the caudatum group prefers, so we have excluded Phrag wallisii, lindenii, caudatum, etc. from this set up. At this time we are growing all of our besseaes on top of the bench in the diatomite, and they are doing better than they ever have. The rest of the adult Phrags have been moved into a 50/50 mix of diatomite and CHC.

We are currently experimenting with a mix of diatomite, extra coarse vermiculite and #4 sponge rock for both seedlings and compots. This is mixed in small batches, and is watered before use, as the mix has a tendency to want to separate out into its components, and the water has a cohesive affect on the particles. It is certainly too early to evaluate the results, but it appears to have excellent promise. The advantage is the ability to have a mix that holds a considerable amount of moisture and air simultaneously, but won't deteriorate over time in characteristics due to breakdown or compression. This type of mix may allow for less frequent repotting as the seedling grows. We will certainly be pleased to keep everyone informed as to our progress with this medium."

"Hi Folks,

There have been a large number of questions from our last mailing about potting materials and sources. It is probably better to answer them in another mailing.

Maidenwell Diatomite is a sedimentary rock that was formed from fresh water diatoms in a prehistoric lake in Australia. It is mined, baked at high temperatures and run through crushers and then sized. It is quite a light aggregate and holds a very large amount of water internally.Maidenwell Diatomite is being imported in the north east by http://www.diatomiteusa.com . I have found Joe and his son Michael to be very pleasant to work with, and I believe they are trying to set up distributors in various regions of the US and Canada. I have been told, but have not personally confirmed that Dyna-Rock II is Maidenwell Diatomite, and also that OFE in Florida is selling it. Again, not all fresh water diatomite is created equal. I obtained samples of fresh water diatomite from North American production and it had very different characteristics and was not suitable for use. You also have to be careful of contaminants that can be harmful to you, the Maidenwell Diatomite is tested and certified safe. Someone asked if it can be reused. It certainly is durable but I would consider heat disinfection before reuse, and when you factor in the energy cost that may not be as cost effective or environmentally effective as buying new. The used material makes a great very slow breakdown garden mulch! The one improvement I would like to see in this product is the uniformity of particle size.

Bob & Lynn Wellenstein AnTec Laboratory"

Joe_DiDomenico
Here's a brief autobiography to give you some idea who I am and how I got here tonight.

I live in Buffalo, NY (no snow jokes!!) with my wife, Diane and 3 grown children. This past June I retired after teaching Social Studies in the Buffalo Public Schools for 31+ years. I taught Social Studies- the last 17 years- Economics, Entrepreneurship, and Government to seniors. My son-in-law and I currently own a respiratory homecare company (which is 6 years old) where I handle the corporate side and he manages the client care side. I have had several other small businesses and created Diatomite USA this past summer.

I have been a gardener for many years and became interested in orchids about 10-12 years ago. Like so many of you, I now have a full-blown case of 'orchid fever' with several hundred plants and a newly completed greenhouse. I love to try different things while looking for the 'ideal' mix or fertilizer, whatever! I was reading OrchidGuideDigest last April where someone posted about the Maidenwell Diatomite and included some photos of trials done at H&R Nurseries. I tend to be the curious type, so I did a search for Maidenwell and got an email address (before they had their current site up) and began correspondence with Col Clarey. He sent me samples, we talked back and forth, and in July, I had my first container of diatomite here in Buffalo.

Quite honestly, I saw it as an opportunity to create a business as no one else was importing this product into the states at that time. My son, Mike became interested and we are working on this together. Kathy contacted me last month and asked if I was willing to come here and do a chat so here I am!!

John_in_Arcadia_CA
Hi Joe (from one former - retired Social Science teacher to another - mine in 7th grade!!)

N_Calif_Kathy
To start the ball rolling with I'd like to know if the pH of Diatomite (pH 6.5 - 6.9) works to acidify water even if fertilizer isn't used? In my collection that would be a benefit. But would that be a concern for plants that like more basic mediums (like some paphs)?

Joe_D
As far as the pH question- diatomite is basically inert, about 85% silica (a very small percent is soluable) plus other minerals and absorbs fluid readily. As I understand it, has no effect on pH, so the pH will be determined by the solution (water, fertilizer, etc.) that it is soaked in. Orchids as well as other plants can have the pH adjusted to suit by the manipulation of the pH of the solution. So, in the case of paphs, limestone can be added to the mix if the plants need that type of growing environment. (see Bob Wellenstein's article regarding paph needs) [ http://www.ladyslipper.com/calsub.pdf - Joe D]

MarilyninOttawa
I am looking forward to having a Canadian source of the product if it can be arranged. Diatomaceous earth is another term. We have it here is a fine powder form as an insecticide. I've never seen it in pelleted form.

Joe_D
The mining process basically removes the diatomaecous earth as a 'mud' and kilns it to sterilze it and harden it into a 'rock'. It is screened to size it.

Mary_Lou
If I may ask Joe, is the source of this product the sea? [There are both fresh and salt water sources - Joe D]

N_Calif_Kathy
Not to step on Joe's toes, but check http://www.diatomiteusa.com. The diatoms they use are fresh water. Not salt water.

MarilyninOttawa
Joe, what is the strength of the material? ie, can use crush the composed pieces with your fingers or is it more like fired clay? [I would say that it is not as hard as fired clay but much harder than sponge rock - Joe D]

MarilyninOttawa
The diatomite seems to be a lightweight product until it is wetted. Is that right Joe? Just how much water can it hold?

Joe_D
The diatomite is similiar to coconut husk chips as it wicks up water (about 150% of its weight) and releases it back into the mix over time.

Mary_Lou
So this product is basically the same source as Diatomaceous Earth? Is this product is the same chemically as DE?

Joe_D
It is Diatomaceous Earth.

Jade
Joe during the kilning process does it get crystalized?

Joe_D
It doesn't crystalize, as the diatoms already have a silica skeleton which is the framework of the material. Imagine, silica snowflakes.

Jade
Yes, I understand but silica will melt under high temps. I take it the kilning process must be at a fairly low heat. Maybe just enough to make it clump but not fuse?

Joe_D
The kilning process is at 650 C, which drives out the moisture and hardens the diatomite.

Jade
Thanks, Joe, that answered my question very well. Those temps are well below fusing temps for silica. That explains why it retains its wicking capacity even thought it is more rock like.

art,simpsonville_sc
Is there a problem overwatering with diatomite or does it drain like rock and will release moisture when needed?

jim4eq
Joe, are the individual pieces as hard as the clay products like aliflor? Do they break as easily?

Joe_D
Not as hard as aliflor but I would say they break easy - not like spongerock if that is what you mean.

jim4eq
Thanks, those were the comparisons I had in mind.

Mary_Lou
So if it is DE, just in a different form, then the health cautions would have to be the same. Inhaling dust is a risk for cancer of lungs. [This material is low in dust, and once soaked, dust doesn't seem to be an issue - Joe D]

MarilyninOttawa
Should we rinse it before use to wash away any dust? [Soaking it before use should resolve that issue - Joe D]

Joe_D
This is a stable 'rock' with minimal dust, we recommend soaking before use which tends to reduce it further.

janetteh
I have found that there is very little dust with the diatomite. Much more dust is generated measuring out charcoal.

N_Calif_Kathy
http://www.maidenwell.com/techInfo/default.htm click on the .pdf link to the MSDS sheet. called 'MDA MSDS'. Will answer health concerns.

Ed_in_Sat
I must be confused. Is diatomaceous earth a screened fine product and this potting material a clumped, very coarse form? [It isn't clumped, rather looks like a sedimentary rock - Joe D]

janetteh
The product looks just like the gravel we use in driveways in this area, only it is lighter in color and doesn't weigh hardly anything....when compared to gravel.

Joe_D
Diatomaceous earth can be ground for different applications, like filtration. The one thing that Bob Wellenstein 'complained' about was the sizing in the 'medium' and 'large'. There is a pretty good range in size, especially in the 15mm to 25 mm.

N_Calif_Kathy
I like the quote from your home page "We suggest that when using Diatomite in your mix- think larger, looser, less watering, and less frequent repotting!" I admit when we spoke I thought I'd need to use a smaller size for seedlings and pleurothallids. But you recommended the 7mm stuff.

Jade
Kathy, isn't 7mm about the size of fine bark?

N_Calif_Kathy
I think you are right. But I have most of my stuff in moss, and am not doing very well with it. So I asked about diatomite (releasing water etc) and that's what he said.

Joe_D
I have my masd. and related types in basically fine coconut husk chips (chc) and fine diatomite, perilite with a little fine charcoal.

MarilyninOttawa
So you are growing pleurothallids in it with success. Interesting! Can we expect the product to be available through a Canadian distributor anytime soon?

Joe_D
I currently have some product in Niagara Falls, Ontario and I'm working to set up distribution. Contact me.

Zygopetalum
About the dust, even though it's a small amount, would it be harmful if inhaled? [DE dust has the same dangers regardless of its source but this product is relatively low in dust and with common sense handling should pose no significant health risk - Joe D]

Mary_Lou
Remember that charcoal is not a carcinogen. My Oncologist told me that the DE I use in the garden need not be worried about. It comes moist in a bag and does not blow around when I spread it for snails. A sure cure for them, if using this product to pot orchids I would guess you will never see snails and slugs!!!

Joe_D
I'm told that containers of diatomite are shipped to England specifically for the slugs and snails.

Jade
Ah but you might find that your cats like the bigger pots. Noticed at the website it was also being used for kitty litter. [In Australia, the extra fine is used as cat litter. Shipping costs make that impractical here - Joe D]

janetteh
Expensive kitty litter. :-)

pecteilis_in_KY
Joe? What interaction between the roots and the rocks have you noticed that makes better growth, besides the ability to hold water of course? [It has several benefits- silica for sturdier plant growth, retains moisture but isn't wet to rot roots- I cannot say first hand as I haven't had my plants in it long enough- I have relied on various testimonials from both Australia and H&R - Joe D]

MarilyninOttawa
Like with all media types, we would have to try this under our conditions and adapt watering, etc to receive the greatest benefit for our plants. Joe, is there any one kind of orchid that really grows best in this product?

N_Calif_Kathy
Joe, does silica increase root production? Is that an effect of using this stuff?

Joe_D
Silica has the benefit of helping stronger cell structure and in trials in Hawaii, show more robust and faster maturing plants. It also helps with heat stress.

Mary_Lou
Heat sress!! Now that is something I am familiar with here in Miami. (This cold stress is for the birds). In my climate, except for Phals, it is important that the media drain quickly and dries out. Does this product hold water more than Aliflor for instance? Coconut Husk Chips stay pretty wet for here.

Joe_D
I believe that it holds more water that aliflor as it allows the water to wick throughout the medium.

MarilyninOttawa
Joe, have there been any studies tracking the movement of silica from the medium into the plants?

Ed_in_Sat
I think Dave Neal, down at Dyna-Gro has his hand up!

Zygopetalum
Does H & R use it on their larger plants or only for their "plugs"?

Mary_Lou
What about Cattleyas, Dens. etc.

Joe_D
The plants from H&R that I have seen in it are primarily in 7-15mm (#3) diatomite. I'm using medium chc, 7-15mm diatomite, #3-4 sponge rock as my basic mix for most types. I have some catts and phals in straight 7-15mm. [for finer rooted plants - masd, pleuros, etc.- fine chc, #2 diatomite, sponge rock works for me - Joe D]

Mary_Lou
Thanks Joe, then it might be OK for my Phals but not other genera here. [In Miami, Florida]

N_Calif_Kathy
Mary_Lou, why not for other genera?

Mary_Lou
Kathy, where I grow the humidity is so high that if stuff holds water too long some genera will be in trouble most of the year. They just have to drain quickly and dry out. Right now through April humidity is lower then - look out! Think sweaty tropical. And it might be a help for the Phals so we don't have to repot so often. I used to like to plant Phals in baskets with tree fern/redwood chips and not repot for 5 years!! But they have to be mature plants to do well like that.

N_Calif_Kathy
The largest stuff wouldn't work, you think?

jim4eq
Kathy, for Miami the larger should actually be better for catts etc, since more air movement between the 'rocks'

N_Calif_Kathy
That's what I thought too. Larger the better.

Mary_Lou
If the largest stuff held water that would be bad cause it would take even longer to dry out than smaller pieces. [Stewart in Naples (AOS forum) is using it for encyclias- #3 and #4 - Joe D]

janetteh
Mary Lou would almost have to use an inert substance that didn't absorb any water in her situation.

Mary_Lou
That's why I love Aliflor!!! Jim is down here too and Bert and Soggy. But we can't use aliflor straight for Phals!!

Joe_D
Mary Lou, What's interesting is that the moisture is not 'held' at the surface of the diatomite but wicks through it. Even when wet, it is relatively dry to the touch. I think that it would be very useful in your growing conditions, but larger sizes.

MarilyninOttawa
Joe, Thank you for the information about this new environmentally-friendly product. I look forward to seeing it in Canada. Perhaps we can keep in touch. Good night and thanks.

Zygopetalum
Hey Orchidglade and Jim4eq, what do you think about this stuff?

jim4eq
It sounds interesting, I haven't had much problem with snails in aliflor but I use metaldehyde when I do see them. This would be preventive, without chemicals. I also like the wicking action, might be useful for phrag/paph like Wellenstein said. I am trying to find something I can use reliably without having to cook up a 7,928,564 ingredient mix!!

N_Calif_Kathy
Well I thought the same thing. I wanted to get my small pots in a medium that would allow them to be watered on the same schedule as my large pots.... and something to use when I take apart some compots I had. So I thought about this stuff.

Jade
This product sounds good. Dyna gro puts out a product that contains silica . Claims it makes plants more resilient to heat stress and other damages. If plants can take up the silica from this mix it would even be a better deal.

Joe_D
Dyna-rok II is the same exact product in their bag and label. [not Pro-tek - Joe D]

Mary_Lou
The silica spray is different. It is applied to the leaves of the plants. I have had commercial growers of Phals say they had to cut back on using it because their leaves got to 'crisp' they would crack and bread too easily! It protects the leaves from damage from mites and diseases etc. by toughening the cells.

N_Calif_Kathy
I noticed in the handout that H&R also said to use a good fertilizing regimen, because this stuff is inorganic, so you 'd have to have a fertilizer with micronutrients. And Calcium too?? [Diatomite doesn't replace your normal fertilizer schedule and program, while it adds trace amounts of minerals like calcium and small amounts of soluble silica, it is not a fertilizer - Joe D]

janetteh
But why would this make a difference? Does your normal media supply micronutrients to the plants?

N_Calif_Kathy
I just remember something Fordyce once said about growing in an inorganic medium. One has to be sure all the micronutrients are present in the fertilizer. (But I take Janette's point.)

jim4eq
By the time you mix it with chc and charcoal, you have the organics in there anyway! Plus, Miami water has plenty of calcium, LOL! Just ask my *white* pots!!!!!

Mary_Lou
Unless you are potting in old fashioned osmunda you need a complete fert. Including chelated iron and magnesium. We have lots of calcium in our water here.

Joe_D
There is a small amount of calcium in diatomite.

N_Calif_Kathy
Does it 'salt' out like lava rock? I liked Wellenstein's comment that it might be more economical to toss the stuff rather than reuse it, and I wondered if it would get crusty in hard water.

Joe_D
It doesn't retain salts, but most all mixes benefit from regular flushing.

N_Calif_Kathy
OK, that's my last worry! LOL!

janetteh
I think that Bob's comments were based primarily on not reusing anything that hasn't been "sterilized" first. It wouldn't be feasible for him to reuse it with his operation, but if a hobbyist wanted to pick through the old media and get it out, clean it up and reuse it, I don't think that there would be a problem. You could use heat to kill any contaminants or a bleach solution. But with the bleach, you would have to rinse it 5 or 6 times and then let it sit for several days.

Jade
Kathy, after it was finished as an orchid growing medium you could incorporate into your potting mix for house plants or stuff in pots outside. Website said that a major maker of potting soils was using it in their mixes.

N_Calif_Kathy
Or sift it out... sterility could be a problem. I'm so dang lazy. Heating it up would probably be easiest.

Jade
Baking growing medium in the oven can produce an odor that is less than pleasant.

janetteh
Kind of like baking old clay pots or sterilizing terrestrial mix. Yuck.

Joe_D
For sterilizing we have suggested physan 20 or similar products to the hydroponics market as they reuse the #3 as they don't have the mix problem we orchid growers have to deal with.

N_Calif_Kathy
You've made my life easier still.

jim4eq
I definitely want to try it, I've got several compots coming out and can "taste test" it, *G*

N_Calif_Kathy
That's what I want it for, if the big growers are using it for 'plugs' then so can I

Joe_D
It is used in plugs in Australia by commercial growers.

N_Calif_Kathy
So what's it like potting something in this? Just shake it in and around the roots? Is potting easier? Less 'firming up'?

Joe_D
The smallest size can be put on top of your current mix and it will work into it. I think that the smaller sizes will work very well with promix for many different plants.

janetteh
I just measure it out as a component of my mix. No special handling required. :-) [Check out our mix suggestions on our website: http://www.diatomiteusa.com under 'Orchids' - Joe D]

barbara_in_no._CA
I wonder, if I mix some Multi-cote into this, to make up lack of microtrient, will that work? I'm always looking for the easy way.

EDDIE_IN_GA
It appears the biggest cost factor is the shipping?

janetteh
That is usually the case. :-)

N_Calif_Kathy
Joe, how would this stuff work for Lycastes? Has anyone tried them in it? (Another one of my troublesome plants) [I have lycastes and gongoras in my standard mix and they are all doing very well. - Joe D]

jim4eq
uhhh, maybe a dumb question but what isn't troublesome? te-hee-heee-heeeeeee

Jade
Joe, this has been most interesting. Do you have an email or are you setting up distributors all over the country? [jad2@buffnet.net and I am looking for people (individuals or companies) distributing for us. Contact me for wholesale and full bag prices - Joe D]

Randy,_MI
It was an interesting talk.

Adam's_Eden
I have been looking for bulk aliflor I will need to look at this material more.

N_Calif_Kathy
I wondered if he could expand on the idea of it wicking away from the surface and so not being too wet (like in Florida) But I suppose I could ask him later.

Randy,_MI
He said that it shared that property with chc, and I can testify the chc definitely does it. Outside dry, inside wet--root hairs grow into chunks and always get both air and moisture.

janetteh
The prices he has listed on his website for the 20 liter package...figure that is about a 5 gal. bucket of the rock. If some of you just wanted to try it and see if you liked it, that would be the way to go. If you had a bunch of plants, you might want to convince some of your orchid friends to go in with you and order a pallet of rock. It is much cheaper per unit that way, but a pallet is 40 40liter bags.

Adam's_Eden
I could go through a pallet

Mary_Lou
It's always good to have as many things in our arsenal to use as we can. I am still concerned about the health issue because it seems to be downplayed so much. Each bag of DE carries warnings on it and this product should too. It may have a problem getting approved for Florida use if it does not. Florida is strict on labeling.

N_Calif_Kathy
Once you read the MSDS I think you'll be satisfied

Mary_Lou
Just one last note. The inside staying wet is where the problem here. It all needs to dry out quickly INSIDE, not just outside or the roots rot.

N_Calif_Kathy
Janette, a pallet is a huge amount!

janetteh
Depends on how many plants you have that need repotting. :-) But it will keep. Just an up front investment.

jim4eq
I want to try a bag or two before investing in a bunch.

Michael.Exler
I am always open to trying new products, with in reason. Maybe repot a catt. and a bulb. Just for kicks

N_Calif_Kathy
Same here.

Adam's_Eden
I like aliflor, I have been looking to sell it with my supplies, and starter kits. True, I should use it first, but you all converted me in the short time I was here.

N_Calif_Kathy
Have you tried any of this Janette?

janetteh
Am using it now. Haven't had it long enough to make any statements about it. Our main problem is trying to keep plants wet enough during the summer months and this is the main reason I decided to try some.

The end.