In-ground Planting Mix

From: Dan Levin levin at pixar.com> on 2001.07.16 at 14:07:18(7041) I've dug out a modest area inside my greenhouse for an in-ground planting area. After placing a 4 - 5" [10-12 cm] layer of drain rock in the bottom of this pit, I'll be topping up with another 18 - 20" [45-50 cm] worth of planting mix; as the native soil here in the San Francisco area is essentially clay. +More My intent is to grow a mixed collection of tropicals in this bed. >From Araceae: Amorphophallus, Anchomanes, Anthurium, Alocasia, Dieff., Philo's, etc. etc.; some Heliconia, various Zingiberaceae, Bromeliads, Palms, Cycads... the usual suspects! Does anybody out there have any experience/ words of advice concerning conservatory (in-ground) soil mixes or specific materials to either use or avoid? I'm considering a mix comprised of locally available components which I'm blending at the approximate ratio of - 40% coir (in lieu of peat moss) - 30% red lava gravel (graded 1/4" size [6.5 mm], clean) - 20 % fir bark (also graded 1/4", clean) - 10% horticultural sand My sample of the above looks great- but I'm really concerned what it'll turn into 5 years from now. Especially since my preference is to not dig out the entire bed and replace the contents much before 2010, if at all possible. What do the under-glass botanical gardens do? Anything special used for the beds inside MOBOT's Climatron for example? Thanks, -Dan

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