Acacia and Rock Dust Fertilizer

[druid]

Dear Australian Garden Gurus,

By some miracle, I finally got a bumper crop of acacia obtusifolias to survive past the notoriously difficult "early seedling stage", where the death rate is staggering, apparently from damping-off fungus.

Now I need to figure out the rock dust issue. I called my nursery and they have two rock-derived products:

1) "chipped shale"

2) "rock dust phosphate", NPK 0:4:0

Does anyone have idea whether either, none, or both of these products would satisfy the finicky demands for rock minerals that the acacias crave?

I was told they prefer "rock dust" or "granite chips" by a little birdie.

I know they don't like too much nitrogen, but what are the general acacia requirements for phosphate and potassium (P&K)?

Any takers??

DRUID

[ 31. October 2003, 08:37: Message edited by: druid ]

[mescalito]

Hi druid!

I had great results with common potting mix & shale chips....a nice even mix of both

Good luck!

[Ed Dunkel]

I would presume this extends to most native plants (not all), but keep it (very) low on the phosphates.

Australia is an old continent and most of the quite soluble phosphates have been leached out of it. Just keep that in mind when dealing with natives. A number of australian native plants have specially designed root systems that can extract and use very small amounts of available phosphorus and thus are easily overwhelmed.

If you are going to use fertilisers with some phosphorus in it (P Value in the NPK list) then when you see signs of phosphorus poisoning stop applying any more of it.

[druid]

Thank you for your suggestions!

What are the signs of phosphorus poisoning so that i can recognize it? I will not apply any more standard fertilizer now that I know this.

Great warning! Thank you!

DRUID