You're correct! ;-)
Fir bark = 1/4 - 1/8
Turface/Granite = 1/16 insect screen.

Josh

Great! Thanks! I don't have to buy so much turface then :)

Another question... From what I read, one of the advantages of the gritty mix in containers is that it doesn't compact like regular potting soil and suffocate the roots. Why doesn't that happen to trees that grow in the ground with regular dirt soil?

Sure thing! ;-)

Soil in the yard does compact or *settle* - however, there is a wealth
of soil biota that burrows, roots, and worms through the yard to increase aeration.
Also, the ground itself acts as a huge wick, if you will, to draw moisture away from
roots.

In certain yards, though, you will find compacted soil or soil that retains moisture.....
and in those areas, roots will suffocate if they can't grow into looser, more aerated
regions of soil.

Josh

Just an addition to Josh's good comments about compaction: soil compaction is one of the most common problems of the landscape and lawn. We just don't think about the problems that foot traffic (for example) can cause!

One of my most useful 'perscriptions' for declining trees or lawns is to core-aerate! ;-)

Absolutely! ;-)

Aerating lawns is a great idea. I also de-thatch the excessive "bermuda" grass that builds up.
It's a chore, but it really improves the look and texture of the lawn area.

I recommend the de-thatched grass mulch be kept in bags until it is completely dead/composted.
But I digres....

Josh

Thanks for the info/advice!

What are people's opinion on putting earth worms in pots filled with regular pre-packaged potting soil? I think I've read conflicting things in this forum about it being good and bad.