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Soil for a large raised bed - Tucson

Posted by Melt_In_The_Sun 9a (My Page) on
Tue, Dec 11, 12 at 14:25

Hi all,
I posted this elsewhere, but got no responses...this seems like a good group of people from AZ, so I hope someone can help me out!

I have a nearly complete raised bed that will need 5 or 10 yards of soil. It's going to be a general purpose bed, with various small trees/shrubs/succulents/etc. in it. I need some advice on what kind of soil to use. Most of the plants we'll be using would probably be OK in the native soil, so I'm thinking that a sandy screened topsoil would probably be OK. But, many of the vendors around here have a raised bed mix that contains a lot of compost. I know that the soil isn't great, but I don't want to make it too rich.

Here's my wife's first-pass list of ideas. This area will be spine-free.
Aloe fleurentiniorum
Aloe karasbergensis
Aquilegia chrysantha
Boophone distichia
Caesalpinia gilliesii
Chaemerops humilis
Convolvus cneorum
Dichrostachys cinerea
Drosanthemum floribundum
dwarf citrus
Echeveria (will try a few things)
emu bush
Erythrina flabelliformis
Graptopetalum paraguayense
Graptoveria 'Fred Ives'
fernleaf lavendar
Hardenbergia violacea
Haworthia coarctata
Hibiscus coulteri
Malephora crocea
Melampodium leucanthum
Mirabilis jalapa
Scadoxus multiflorus
Scilla peruvianus
Urginea maritima
�Mangave 'Macho Mocha'
Yucca 'Blue Boy'/"desmetiana"

Maybe some bigger stuff too:
Acacia willardiana
Vitex agnus-castus
Sophora secundiflora 'Silver Peso'

Thanks for any advice!

Follow-Up Postings:

RE: Soil for a large raised bed - Tucson

If your native soil is truly sandy it might work OK, but I've found that although my native soil works great in the garden, it is a complete disaster once I use it in any amount in a pot or raised bed (or the compost pile for that matter). This is due to the clay content.

Now I make my own potting soil with volcanic scoria (cinder) mixed roughly 60/40 with some fluffy organic material such as compost. It works really well for me and is basically free, since I make the compost myself, and collect the scoria from a nearby volcanic hillside. Without that much compost you could use peat or some inexpensive compost available by the truckload.

I think you'll have better results if you avoid anything loosely called "topsoil" since this can often be bare mineral soil with no organic matter, lots of caliche, and a high clay content.

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