it does not matter as long as where a dust mask which is advisble when gardening any way to keep bugs out of your mouth and nose.

The perlite will float, vermiculite doesn't as much. Perlite is pretty much useless in my opinion. I really don't think you need as much of either as the book says. If you add a lot of peat moss it serves the same purpose of helping the soil hold moisture.

What it is useful for is germinating seeds.

Hi Sanj;

josiwax is right, Perlite is useless. Vermiculite is much better.

CloneZero

Doesn't perlite create air space for the roots? I don't use much peat because of the whole environmental issue with it. I use mostly compost, lots and lots of compost.

"Doesn't perlite create air space for the roots?"

Not really. It pretty much forms little rounded balls like styrofoam. It tends to float to the top of soils, and it crushes to powder easily. It doesn't really have space where the roots can access air. Vermiculite, however, is thin sheets of material which are expanded to have spaces in between them. These spaces hold water and air and are accessible by root hairs.

Great guys...based on your comments, I will be buying a big bag of vermiculite for my garden.
Ok since perlite is like styrofoam, can I crush styrofoam, and mix it with soil? will it make soil fluffy as well? Has anyone experimented with this?
I understand that perlite and styrofoam are completely differnt products.

Perlite is not *that* much like styrofoam, and though it crushes easily, its still a mineral when it breaks down, where styrofoam breaks down into refinery products - which one would you rather eat?

I checked American Clay Works. They quoted me $40 a bag. Maybe they realized they could get more for it. That is how much it costs at O'tools or Garden Country in Broomfield. Well that posting was back in 06 so the price has definitely gone up.

I left a bag of vermiculite out in the rain and a bag of per lite also. Accidentally of course. The vermiculite seemed to hold water like crazy and per lite just drains. The both help prevent compaction as far as aeration I use the felt smart pots so I'm not too worried about it

from HGTV web site:
Q: What's the difference between vermiculite and perlite?

A: Both vermiculite and perlite are sterile products used as root-cutting media and as components of various potting mixes, but there's one distinct difference between them.

Vermiculite is a mineral--mica, to be exact. When heated, it puffs up, and in this state it absorbs and holds water. However, due to its tendency to compact, it shouldn't make up more than 25 percent of a potting mix.

Perlite is a white volcanic substance that is a derivative of silica. It too is heated so that it puffs up. Yet, perlite does not absorb water, making this the main difference between it and vermiculite.

vermiculite is used primarily in potting mixes (because of its water-holding capacity) and perlite for rooting cuttings. However, because perlite is sterile, the cuttings must be replanted in a potting mix that contains nutrients. Do this once roots begin to form.

You can use both perlite and vermiculite interchangeably. Because perlite and vermiculite are roughly one-tenth the weight of sand, they are ideal additions to potting mixes for folks who garden on terraces or rooftops where weight is an important consideration.

Note regarding vermiculite and cancer risk: Is there asbestos in the vermiculite sold for gardening uses? from www.health.state.mn.us

Not all vermiculite products contain asbestos, but some do. An EPA study showed some vermiculite products contain low levels of asbestos. Asbestos is found primarily in the unmixed vermiculite product although some was found in pre-mixed potting soils. For consumers using vermiculite on an infrequent basis the health risk is low. Greenhouse workers in daily contact incur a higher level of risk.

Here is a link that might be useful: Vermiculite and Gardening Use

I don't use either one. Twigs, wood shavings, news paper, leaves, yeah just use compost it works well for me.

IMO if you are trying to do Mel's SFG method, I think Perlite and Vermiculite aren't economical at all, they are expensive. If you wanted to get the same result with what those 2 things do, then get sand if you want to loosen the soil and improve drainage or mix compost (or clay if you have a sandy soil) into the soil to help with water retention

Bought both of these products to pot a robellini palm tree, was told vermiculite was good for drainage!! Just read to the instructions & says it's good for holding moisture, which I don't really want. Thought I might mix tiny gravel particles to my compost instead of using either of these products to create good drainage. My robellini is planted in soil with John innes no 3.. Put is starting to look yellow. I have been told this is too strong a mix, has any one got any ideas on potting a robellini, please.

I really can't agree with some of the earlier comments. I use perlite to help with drainage and keep the soil from compacting, and I think it's good for that purpose. Vermiculite have it's own use to hold moisture, but it can get compacted over time especially heavy soil which can cause issue with drainage later on. Both perlite and vermiculite have aerating effect, in fact perlite is better for aeration in the long run than vermiculite since it can hold it's structure better. Vermiculite is better for seeds germination, perlite have it's usefulness for hydroponic growing. They are not better or worse than the other, just meant to be used for different purposes.

Since my mix is already water retentive with coconut coir, perlite is a better conditioner material for it than vermiculite.

Sand does not seem like a reasonable substitute for vermiculite or perlite. The particle size is much smaller. In Mel's book, peat and vermiculite serve two different purposes - peat to retain water and vermiculite or perlite to keep the soil "fluffy" or make sure it has air space. Her use vermiculite rather than perlite mostly for appearance. Many seed starting mixes are half peat and half perlite.

Gravel does not sound like a good idea either. How would carrots turn out if there was gravel in the soil?

Perlite is a closed cell substance - that means that the "air space" it creates is all INSIDE each piece of perlite and makes no difference whatsoever to the plants.

Gravel and sand added to non-sandy soils (say to a clay or clay loam) are not of any help either. If you want a sand-based mix - say for something that needs extraordinarily good drainage, like rosemary and lavender - that's one thing. But working it into a peat-based mix is not helpful and often counterproductive.

Pumice is a good soil amendment (in the right size) but few of us have access to affordable quantities. GrowStone is a pumice-substitute made from recycled glass, but it is too fragile (and expensive IMO) for use in a raised bed. I use it in my potting mixes all the time though.

What I use to fill a raised bed is a mixture of pine bark and peat. About 1:3 bark:peat. Then I mulch with a layer of brown cardboard (like they use to make moving or shipping boxes, no cereal boxes or the like) and cover that with whatever mulch is at hand - spent hay or straw if I am in a rural environment, bagged non-dyed pine mulch now that I'm in a desert, trucked in composted yard waste when I'm living somewhere where you can get that from the city for free or cheap, and bulk pine bark if I can get it and nothing else is available. All depends on what's available locally.

The quality of peat I can find has gotten worse and worse over the years. This year I could only get a superfine peat that is intended to be used as a lawn top-dressing. Both Lowe's and Home Despot stopped carrying the big 4.5cu foot bags of the coarser grade of peat. I think I paid $10 a bag for that last year; this year I'm stuck with the fine-grade stuff in a 3cu ft bag for $13.

The only other option was $40 a bag from a local "greenhouse". And it turned out that wasn't a good grade either.

We are all just going to have to get used to making changes as sources for this kind of thing dry up. I haven't been able to get real, coarse vermiculite in decades. The supposedly "coarse" stuff offered to me in the last 20 years or so is never coarse, it's always medium grade. I've given up totally on vermiculite, but can't really do without the peat. Hopefully when I move back to the green world and out of this desert, I'll have a few more choices - but things are slim-pickin's on the planting medium front these days pretty much all over.

Both good and poor info is given here. If your really interested in the facts of vermiculite / perlite go to this link. This is the MFGs company. a lot of questions can be answered here.

http://pvpind.com/Contact-Perlite-Vermiculite-Packaging.aspx

Can a fine or coarse gravel help if perlite and vermiculite cant be found

Moisture is absorbed into the vermiculite itself, perlite holds moisture in its cracks and crevices. Using gravel in my opinion defeats the purpose. Vermiculite can be located, just about anywhere, not in the big box stores, try a mom and pops local farm supply shop...ask them to order. Remember, extra course vermiculite is also available. here's a link to U.S data base. https://docs.google.com/spreadsheets/d/17MoZex4Hg0HyT75bSKn-1leQNG153RBvxkb5WggatmE/edit?hl=en#gid=0

Thanks I live in finland so getting anything out of the norm is difficult they even confiscated my nutes

I found vermiculite in the insulation section of a local home store (Menards). I doubt they are in the Rocky Mtn. area but maybe an equivalent store?

Since this item is related to food and sold as an insulation product it very well may have some objectionable items added for fire prevention, etc. Horticultural vermiculite is advised...Give this site a browse, if needed contact them , they are very pleasant. http://www.pvpind.com/Contact-Perlite-Vermiculite-Packaging.aspx

Vermiculite in a raised bed is just not needed. The best solution is heavy mulching and letting it build up over time; other than that, stick to the bark/peat mixes if you must fill a raised bed more quickly than nature can manage (or if you don't have access to cheap organic material).

Do not add sand or gravel of any grade. Do not add perlite - it has NO nooks and crannies and holds NO water other than by surface tension. That tiny little bit of water is not easily given up to roots. It does nothing to aerate the soil. The only thing perlite seems to be good for is floating up out of your mix and looking ugly. It apparently does have uses in hydroponics, but that's about it.

Worms are your friends. Organic matter is your friend. Cardboard covered by mulch is your friend. Peat and pine bark (in small sizes, like under an inch) are your friends.

Everything else is a useless waste of time, effort and money.

I'll agree with everything you stated, however, vermiculite has served me well. It is not useless in my opinion and works for me. Will I continue to use it ? Don't know about that one, I only read about the Square Foot Gardening program, followed it to the T, received results so far above my greatest expectations. This program exposed me to the wonders of compost, microbes, and doing away with all the nasty stuff I once used. I suppose as one goes further in knowledge about anything, experimentation will support changes.

I used vermiculite for literally decades starting 50 years ago, until I couldn't find it reliably any more starting about 25 years ago. I swore by it. And for a long time I couldn't come up with anything better.

But now it is nearly impossible to find in the very coarsest grade - I haven't seen anything I'd call anything but medium grade for decades. It breaks down rapidly in soil and I would never even consider using it in a raised bed, it just breaks down too fast. And it's always been too expensive in the quantities I would need to add at least every other year to a garden-in-the-ground! For me at least.

Not saying to dig up plain dirt to fill a raised bed, but use something the worms will help turn into friable fertile soil over time. Like bark and peat. Dirt on the ground needs to be friable soil, not container mix. I loves me some earthworms! And all their soil flora and fauna kith and kin.

Keeping in mind I mean a raised bed on the ground.

Now if you're talking raised beds as in a box that is up off the ground, like a container - for that I'd go with a Growstone based mix. Lightweight even when wet, very friable, its a very very usable container mix.

I know the Turface based gritty mix is very nearly sacrosanct on these forums, but (1) I've never had access to Turface in less than pallet quantities, and seldom that, and (2) that mix is SUPER DUPER heavy.

I've tried all the other container mix ingredients/soil amendments I could lay my hands on. Calcined clay, crushed pumice, etc etc. None of them worked as well as my peat-bark-vermiculite (I have always hated and avoided perlite) Cornell container mix.

Until now. Growstone is saving my container plants, LOL!

But it is too expensive and fragile to put in the ground. And just not necessary - using mulch and cardboard as a weed blocker (which also eventually is pulled down into the soil by the worm armies) improves all soil types, even heavy clay, much quicker than double-digging and and cover crops and constantly adding compost ever did for me.

I have never understood why Mel was so set on vermiculite for raised beds on the ground. It never lasts more than a couple of seasons at best, and if you don't need it later (as the soil "matures"), you didn't really need it to start with. Since I've been getting along without it for over 20 years, and NEVER used it in the ground anyway, it just isn't necessary. Worms do all my work for me. Worms, and cardboard to keep the weeds out.

If you're prone to slugs its a bit more complicated, but I've done it that way (cardboard covered with wood mulch) even in Portland OR, slug capital of the US, and Ohio, close second in that category, LOL!

Hi Z.

In case you're not aware, A grade called ( extra course ) is available. There are many folk out there that if it's not easy to get they quit. The folks at PVP are quite nice to deal with and answer any pertinent questions. I'm going to look into growstone, sounds interesting.

I keep seeing it mentioned on line, but I have yet to find somewhere to actually BUY it - at least local to wherever I've been living at the time (all across the country). In the past 25 or 30 years anyway. Shipping costs make it stupidly expensive if I can't buy locally.

I know its out there, but - like Turface - it continues to elude me. And isn't worth the trouble after all, I've come to decide.

But to each their own.

I just read about some benefits and different between vermiculite and perlite. They make the plants drain quickly.