Jack wrote:
The local nursury is selling compost. $23/yard vs $20/yard for loam. Their
loam is way to rocky. I am building raised beds. Will a raised bed of
compost have enough structure for growing large shrubs?
.
I know this sounds like a crazy question, but this stuff is so light and
fluffy. Really nice though.
Thank you.



Unless the bed is raised 3-4 feet above the natural grade, you will
create problems using only compost. What you should do is dig down
inside the bed to a depth of at least 4 feet from the top of the
expected planting level. Break up the clods; a four-prong "potato hook"
cultivator is excellent for this. Then mix the compost with the native
soil, using enough compost so the result comes to the top of the raised
bed when packed down firmly. Use a spading fork for mixing. (Don't use
a pitchfork, which is likely to break.) While mixing, include some
phosphorous (bone meal or superphosphate); phosphorus does not leach
through the soil and must be placed where roots will find it.

The result will be a soil mix that does not inhibit shrub roots from
growing beyond, into the native soil.

--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 21 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a, very close to Sunset Zone 19)
Gardening pages at http://www.rossde.com/garden/