Any such thing as GOOD perlite?

[fanaticactus]

In my seemingly constant search to lighten my soil mixes, I keep trying to find something else than perlite. Yet I see it's recommended in almost every recipe for any substrate that's used to keep roots in an airy mix. In my area, it seems that Miracle-Gro has a strangle hold on the perlite market. Rarely can I find anything else. I've become so disappointed in the quality of their product because almost every bag I've bought contains practically pure dust; it looks like very fine snow. It's almost as if the bags have been run over by tractors, pulverizing the contents. Has anyone else found this to be true as well? Has anyone found a different brand of perlite that has decent sized pellets? Old fashioned vermiculite seems also to have become too fine to do much good. I use diatomaceous earth, as found in Napa/Oil-Dri; but other than that and aquarium gravel and the coarser sand sifted from bags (a tedious and time-consuming task)--and all three of those make a heavier mix--I know of nothing else in the way of additives to help the porosity of the soil.

[DaveW]

When you can't find things locally always try EBAY:-

http://www.ebay.com/sch/i.html?_from=R4 ... ted+States" onclick="window.open(this.href);return false;

[iann]

I wouldn't have thought Oil-Dri was too heavy. I find perlite to be far too light Other than weight it should be at least as good as perlite as a soil additive and no reason to seek out perlite if the oil-dri is easily available. I think it is better, but you should be aware that it will hold more water than perlite, except maybe Miracle Gro snow perlite. Besides, perlite is nasty and ugly.

[fanaticactus]

When you can't find things locally always try EBAY:-

http://www.ebay.com/sch/i.html?_from=R4 ... ted+States" onclick="window.open(this.href);return false;

Thanks, Dave. It looks like that's going have to be the route I take. After experimenting for three or four years with varied batches of soil, I'm about at my wit's end, especially when the quality of what's commercially available seems to have plummeted.

I wouldn't have thought Oil-Dri was too heavy. I find perlite to be far too light Other than weight it should be at least as good as perlite as a soil additive and no reason to seek out perlite if the oil-dri is easily available. I think it is better, but you should be aware that it will hold more water than perlite, except maybe Miracle Gro snow perlite. Besides, perlite is nasty and ugly.

I think you've summed it up quite well, Ian!

[DaveW]

Perlite is also available in a few different grades or particle sizes:-

http://www.william-sinclair.co.uk/files ... erlite.pdf" onclick="window.open(this.href);return false;

[fanaticactus]

Perlite is also available in a few different grades or particle sizes:-

http://www.william-sinclair.co.uk/files ... erlite.pdf" onclick="window.open(this.href);return false;

Wow! I was wondering if it came in various grades, Dave. It seems that the UK really has plant lovers' interests at heart. I've seen so many products from there that don't exist over here. Here the attitude seems to be: This is what we make and we don't care if it's exactly what you need. If you don't want it, don't buy it!" I'll have to do more detailed research on line to see if I can find some and, just as important, the exorbitant postage rate I'd have to pay. Thanks again.

[DaveW]

America is just a bigger country than the UK, you probably have many similar products but just have to search further afield to find them. EBAY is often a good start to find just what is available, also use Google or similar to search the Internet. However equipment for small greenhouses like vent openers is probably more common here since we rely on those more not having the climate to grow tender plants outdoors, plus with smaller amounts of land around properties things like 6ft x 6ft greenhouses would be more common here.

For instance I just Googled for "Perlite America":-

http://www.perlite.net/" onclick="window.open(this.href);return false;

Amazon sells it but I don't know what grade:-

http://www.amazon.com/s/ref=nb_sb_noss_ ... ds=Perlite" onclick="window.open(this.href);return false;

[fanaticactus]

America is just a bigger country than the UK, you probably have many similar products but just have to search further afield to find them. EBAY is often a good start to find just what is available, also use Google or similar to search the Internet. However equipment for small greenhouses like vent openers is probably more common here since we rely on those more not having the climate to grow tender plants outdoors, plus with smaller amounts of land around properties things like 6ft x 6ft greenhouses would be more common here.

For instance I just Googled for "Perlite America":-

http://www.perlite.net/" onclick="window.open(this.href);return false;

Amazon sells it but I don't know what grade:-

http://www.amazon.com/s/ref=nb_sb_noss_ ... ds=Perlite" onclick="window.open(this.href);return false;

Thanks very much, Dave. The first link is a particularly interesting one. And I would want to know what grade I'd be buying, so I'll search that out. At this point, I'm so fed up with the junk they commonly sell in stores, I don't even mind the extra postage.

[CactusFanDan]

In response to the title: no. Try to find pumice if you can, otherwise hard-fired clay products are good too.

[Steve Johnson]

In response to the title: no. Try to find pumice if you can, otherwise hard-fired clay products are good too.

That's what I have to say for the benefit of our US members -- why make do with perlite when you can get pumice? Maybe I have to lead y'all to this, so here we go:

http://www.ebay.com/sch/i.html?_odkw=ho ... e&_sacat=0" onclick="window.open(this.href);return false;

From this link, you'll have to do your own research on the sources you want to go with. In terms of grain sizes, smaller is better -- look for the 1/16"-1/4" aggregate range. Avoid pumice with a lot of big chunks, I wouldn't bother with anything that's mostly 3/8" or larger. You should find plenty of sources to choose from. And please, please, please -- don't even think about vermiculite!

[fanaticactus]

Thanks to all the good advice you've all given me, I've just ordered 3.5 gal. of pumice. Now, as for the amount to combine with DG... I imagine it depends on the climate where one lives, but are there general guidelines or doesn't it much matter? Are we talking 50/50 or more like 70 DG/30 pumice, or somewhere between? And do I dare ask about the advisability of mixing in a dash of earthworm castings for a bit of fertilizer or sphagnum for texture and more moisture retention?

[Steve Johnson]

Thanks to all the good advice you've all given me, I've just ordered 3.5 gal. of pumice. Now, as for the amount to combine with DG... I imagine it depends on the climate where one lives, but are there general guidelines or doesn't it much matter? Are we talking 50/50 or more like 70 DG/30 pumice, or somewhere between? And do I dare ask about the advisability of mixing in a dash of earthworm castings for a bit of fertilizer or sphagnum for texture and more moisture retention?

Well, congrats on getting the pumice! Before we continue -- what kind of DG do you plan on using? Coarse aggregate to match the pumice, or will you be using some of the "play sand" DG for your mix as well? That "play sand" is not exactly a good substitute for soil, and hopefully the coarse pumice/DG aggregate is the only stuff you'll be going with. If you feel the need to add soil with your mineral component, even a commercial potting mix would be better if you can extract out as much of the organic crap as you can. But do you even need it? Here's where it's helpful to know your options...

For those who aren't familiar with its properties, pumice has the unique combination of open porosity and the ability to hold a surprising amount of water. In fact, a number of people grow their cacti and succulents quite successfully in nothing but pumice. Whether you can or not depends on your climate. I have a favorite expression describing overall climates in the southwest -- "dry as a popcorn fart". Maybe not the best place for using straight pumice, so I have a feeling that growers in the desert need soil in their mixes for moisture retention. My coastal microclimate is rather humid, on average the RH tops out at 80-90% during the day and 35-50% overnight. If the climatic humidity in your area during spring and summer is similar, the only reason to add soil in your mix would be for any cacti that can't support proper growth of their really fine root systems in a coarse mineral aggregate. Now let's discuss DG...

The only reason I use it is to make my pots as heavy as possible so they don't tip over in the wind. However, because we're talking about the coarse stuff, the DG actually works against the amount of moisture being retained by the pumice as it dries out. The 60/40 ratio of pumice to DG has been pretty much perfect for me, and I think I got lucky about finding the sweet spot with a humid climate and more temperate summers compared to what the inland folk have to deal with. If your humidity is high enough but your GH gets hotter during the day, DG in the mix may be a liability. Such being the case, straight pumice on its own should avoid the pitfall of having a pumice/DG mix drying out too fast in your summertime heat. If you end up deciding on a pumice/DG mix -- definitely tilt the ratio in favor of pumice!

Don't know if a dash of earthworm castings would do any good, but I don't think it'll hurt either. Sphagnum = peat = bad news -- avoid it like the plague. Go back to what I just said about soil.

[fanaticactus]

Thanks, Steve. Good details for me to keep in mind. Our climate, being New England, is extremely variable. We are in a low valley surrounding Lake Champlain, and my location is actually closer to the NY shore than the VT shore--i.e., on the western side of the island which, itself, is in the western half of the Lake. The moderating effects of the Lake keep us warmer in winter with less snow and a bit cooler in summer than mainland Vermont. Sort of our own microclimate. The prevailing winds are from the south (straight up the Lake), but we're wide open to the north and west, making for a breezy, if not downright windy spot in most types of weather. Our humidity/dew point is probably considered average. Right now they are 49% and 61F, but I've seen the dew point as high as 73F during our heat waves with a tropical air mass. The temp can be in the 90s for two, three or four days in a row usually three times during a "normal" summer. So much for the climate.

The DG I would use is an auto store absorbent, which I've always used. I wanted some extra "grit" in the mix, so I've sifted some Sakrete "Traction Sand" and have some nice sized irregular rough sand/crushed stone, the size that remains after the finer stuff goes through a regular kitchen sieve (don't know what size mesh that is--maybe 1/16"?) but nothing larger than perhaps 3/8". I wanted something that would still aerate and not compact and would not hold water because the DG and pumice will hold enough, I believe. I'm thinking I should experiment first with a 60 pumice/30 DG/10 grit mix, but not go wild until I see how satisfactory the results are. Reasonable?

[Steve Johnson]

Thanks, Steve. Good details for me to keep in mind. Our climate, being New England, is extremely variable. We are in a low valley surrounding Lake Champlain, and my location is actually closer to the NY shore than the VT shore--i.e., on the western side of the island which, itself, is in the western half of the Lake. The moderating effects of the Lake keep us warmer in winter with less snow and a bit cooler in summer than mainland Vermont. Sort of our own microclimate. The prevailing winds are from the south (straight up the Lake), but we're wide open to the north and west, making for a breezy, if not downright windy spot in most types of weather. Our humidity/dew point is probably considered average. Right now they are 49% and 61F, but I've seen the dew point as high as 73F during our heat waves with a tropical air mass. The temp can be in the 90s for two, three or four days in a row usually three times during a "normal" summer. So much for the climate.

The DG I would use is an auto store absorbent, which I've always used. I wanted some extra "grit" in the mix, so I've sifted some Sakrete "Traction Sand" and have some nice sized irregular rough sand/crushed stone, the size that remains after the finer stuff goes through a regular kitchen sieve (don't know what size mesh that is--maybe 1/16"?) but nothing larger than perhaps 3/8". I wanted something that would still aerate and not compact and would not hold water because the DG and pumice will hold enough, I believe. I'm thinking I should experiment first with a 60 pumice/30 DG/10 grit mix, but not go wild until I see how satisfactory the results are. Reasonable?

Quite reasonable! There's really nothing else I can add, except to say that what I'll call "open" mixes do wonders for the aeration of root systems in potted desert cacti. In my younger days of growing cacti through 1970-1991, it never occurred to me that I had any alternative to the heavy soil-based cactus mixes I was using. Back then if someone suggested that I should grow them in pots full of tiny rocks, I would've said "you're nuts!". As I spent all that time worrying about so much of the collection not doing well. In the 20 years I was away from the hobby, things certainly changed. However, if it weren't for the forum, I'm not sure if I would've done anything but go back to my "old school" ways when I went to the California Cactus Center to start my new collection 3 years ago. After I discovered the forum, I'm sure glad I pulled myself out of it, and the experience I've gained here has made all the difference. If my small contribution helps anyone at all, so much the better!

Experimentation is par for the course, and don't be surprised if you have to make adjustments to your mix. You're on the right track, so I wouldn't expect anything major, perhaps tailoring the ingredients to certain cacti you feel really need it. Do you grow Tephros? If so, I'll spare you the trouble -- 50/50 pumice/soil mix. Doing a "Columbo" here -- one more thing, sir. IMO now is not the best time to be changing your mix since your cacti are already committed to whatever they'll do over the rest of the growing season. Early spring is a great time to repot cacti with minimal disturbance of their roots. This gives them a fresh start with the new mix you'll use as they prepare for a full growing season next year. When you unpot the plants, get their roots as squeaky-clean as you can. I'm a huge proponent of treating cactus roots with 1% Hydrogen peroxide to kill any potential fungus/rot and promote faster healing. This is especially crucial when you move cacti from one mix to a different mix. Soak the roots in peroxide for 15 minutes, gently rinse in running water, then let them dry out completely before repotting. A 1-2 week settling in period is recommended before giving the plants their first watering. I always err on the side of caution and give it 2 weeks, although some growers claim that repotting cacti in winter may be best since that's all the settling in they need before they get their first deep watering of the year when the growing season starts. I happen to be one of those growers now, but then again I had the luxury to chance it with minimal risk given the blessings of my L.A. weather. Are you bold enough? That, my friend, will have to be up to you.

This thread turned out to be more than you bargained for, huh? Anyway, I think we have some good info on the table with this one. Hope you're finding it useful, and I for one look forward to hearing more about your efforts moving forward.

Best of luck, and happy growing!

[Saxicola]

Thanks to all the good advice you've all given me, I've just ordered 3.5 gal. of pumice. Now, as for the amount to combine with DG... I imagine it depends on the climate where one lives, but are there general guidelines or doesn't it much matter? Are we talking 50/50 or more like 70 DG/30 pumice, or somewhere between? And do I dare ask about the advisability of mixing in a dash of earthworm castings for a bit of fertilizer or sphagnum for texture and more moisture retention?

You could try 1:0 ratio of pumice to DG and your plants would do great!

DG is fine I guess and I used it to create my cactus garden in my yard, but for potted plants I use straight pumice with no problems. I'm not really sure what adding DG to a mix is supposed to do over just having pumice. I think a lot of people think they have to make a mix for mixing's sake without having a clear reason why. I'm not directing that at you Steve! I know everything you do is well thought out. That is just a general statement about people making mixes without understanding what each component is meant to do.