Great to have this explained so clearly.

Hetty.

I was always confused between the two, buying it online (which I need to do here) made it more important that I figure it out. One of the things I need to know about any soil additive is whether it floats or not, many of my potted plants are pond plants and it is a major pain to have a bunch of stuff floating out of the pots. Perlite floats - it will work its way out of the deepest pot. Vermiculite doesn't float if it is well soaked before putting in the pond. Mostly I just remember that the white stuff floats, the beige not so much.

Thanks for a thoughtful comparison of these two.

drdawg, that was a fantastic article. Great explanation. Clearly explained.

Jonna, I don't think I would ever use perlite under water. Heck, 90% of what I use for my tropical plants (orchids in particular) would not be suitable in a situation as you describe. Why would you want to even use perlite or vermiculite under water?

Dutchlady1 said:Great to have this explained so clearly.

Ken - great article. I knew which did which but never the "why". Not even 6AM & I learned something today

Really enjoyed reading the difference between the two. I will have to star this. Six months from now I will be questioning which did what Thank you for explaining why vermiculite is good for seed starting and perlite is good for cuttings.

Thanks to all of you for your nice comments.

Thanks you for the clear explanation! I wish the employees at the garden centers knew as much.

They only sell them, Mary, not grow them.

for your kind comments.

Wonderful article. I've heard of both, but really didn't know much about them. To me, perlite looks like little pieces of stryofoam.

It is white and is very light, but it is hard rather than soft. Perlite is a natural, though heated, material. Styrofoam is completely man-made, expanded polystyrene, a plastic. Styrofoam will quickly make its way to the surface if used in potting soil (its 98% air), and though perlite can do the same, it doesn't do it rapidly, particularly if it is wetted before being incorporated into the soil. Some commercial growers (and I guess we hobbyists as well) might use Styrofoam in their orchid media, and the large, fir, pine, or cypress chunks keep the Styrofoam in place.

Ken, I am always using old potting soil mainly because I'm cheap I guess. What I discovered the hard way is that I can use it if it has vermiculite in it but not if it has perlite. I've found my pond too many times with a layer of white floating perlite that worked its way out of the soil. It is a pain to scoop it out with a strainer, but that's the only way I've found to get it out of the pond.

Yep, I would expect that. When I lived on the Mississippi Gulf coast I had a really wonderful koi pond, waterfall and all. It was next to my swimming pool deck and the whole area was pretty tropical (though it wasn't even a sub-tropical area. I just used soil, plain and simple garden soil in my pots that grew water-plants.