On Sun, 26 Aug 2012 16:35:17 +0100, Jake
wrote:

(but forgot to mention ....)

Black soil tends to be high in organic matter/humus and so is quite
rich in nutrients to begin with. But it can also contain a lot of
other things and when you say fine but heavy, that may indicate a lot
of clay content.

So in addition to the pH test that Baz recommends - and this will be
an essential pre-requisite to any recommendation as to what to add to
the soil - you need to establish the type of soil. For example, when
wet, if you get a handful and squeeze it, does it stick together like
a muddy ball or does it remain crumbly? If you poor water on it, does
the water drain through or puddle on the top? When it gets dry (as if,
this year) does it set solid and crack or remain malleable?

A little bit more info is needed if you want constructive suggestions;
otherwise all we can offer is best guesses.

Oh and what plants does she want to grow? If she wants to fill the bed
with rhododendrons then suggesting you add a load of lime will be
daft. Many soil improvers will affect the pH one way or the other.

Cheers, Jake
=======================================
Urgling from the East End of Swansea Bay where sometimes
it's raining and sometimes it's not.