organic garden - vermiculite or perlite?

[2Cor1:8-10]

what do you use for an organic garden besides organic compost and organic soil? We are doing a raised bed. I've been told I should use vermiculite or perlite but I'm not sure those would be good for an organic garden. . . .

any other options?

[Macky]

Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. When it reaches temperatures of 850–900 °C, perlite softens (since it is a glass). Water trapped in the structure of the material vapourises and escapes, and this causes the expansion of the material to 7–16 times its original volume. The expanded material is a brilliant white, due to the reflectivity of the trapped bubbles.

Vermiculite is a natural mineral that expands with the application of heat. The expansion process is called exfoliation and it is routinely accomplished in purpose-designed commercial furnaces. Vermiculite is formed by weathering or hydrothermal alteration of biotite or phlogopite.

Both are naturally occurring minerals and therefore organic by definition. They're basically just puffed like popcorn for use by gardeners.

Neither, however, are necessary in the outdoor garden. Fill your beds with good soil and compost and you'll be fine.

[2Cor1:8-10]

Thanks Robin!

If I just use soil and compost, will it be too thick? I was told that the perlite or vermiculite helps to loosen things up and keep it 'lighter'.

[Macky]

Sufficient amounts of organic matter applied each year accomplishes the same thing over time and does so without encouraging excessive mining of minerals that aren't native to your soil.

Your outdoor garden soil isn't meant to be as light as what you'd have for a potted plant indoors. Container gardening (inside or out) needs soil that drains readily (because containers are easily waterlogged) but still retains a sufficient amount of moisture. This is the purpose of the perlite and vermiculite in containers. If your raised bed has full contact (and thus drainage) with the ground, then these simply aren't issues for you and thus don't require the addition of perlite or vermiculite.