Changing soil pH - rhodos.
Chris Hogg wrote:
On Sat, 16 Jun 2012 06:23:56 -0700 (PDT), Rob G
wrote:
My apologies if this has been covered before - I've done a brief
search and not found anything.
I've an area of some 3m x 6m that I want to plant with rhodos and
azalias. It's currently reading around 7.0 across the plot - ie
neutral. Do I attempt to adjust the whole bed soil and with what, or
should I just dig big planting holes and mix in a lot of peat ?
Many thanks
Rob
Attempting to change the pH of soil is like trying to push water
uphill, IMO, although with a pH of about 7 you may have a chance to
move it a bit, but it will tend to drift back over time. You need to
dig in lots of acid compost and/or peat, and water with sulphate of
iron. As this can require quite a lot of stuff for a whole plot, I
would go for just treating the planting holes; make them about 1 meter
across and say 30 cm deep. After-care should include giving the rhodos
a generous watering with Sequestrine a couple of times a year.
The problem that ericaceous plants have when growing in alkaline soil
is that certain trace elements, notably iron and to a lesser extent
manganese, are not soluble at alkaline pH and are not available in
sufficient quantity to supply the needs of the plant. Sequestrine, or
any other brew of sequestered trace elements, supplies those trace
elements in a form that is soluble at high pH and they are then
available to the plants. An indication of iron deficiency in rhodos
etc. is yellowing of the leaves, although it can be caused by other
things.
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