Carl 1 Lucky Texan wrote:
simy1 wrote:

Excellent post and just what this 'newbie' needed to read.
What would be a reasonable 'rate' to apply wood ashes (from hardwood
charoal used in a BBQ pit - not a grill, no fat drippings or meat
product contamination) to soil (as yet untested) that is likely on the
acid side as it has had leaves (needles?) from 2 large bald cypress fall
on it for decades. It does grow St. Augustine and Colocasia and Alocasis
and several other ornamentals just fine so I wouldn't want to drive it
basic. But it seems some light application would be OK - I just don't
know what 'light' is! Also, I have just begun using a tumbling composter
and was wondering about adding ashes in there - again, at what point do
we get close to 'too much'?

Wood ash has a pH of 10.4. The reasonable rate depends, of course, on
the original pH and target pH. Wood chips have a pH of about 5, which
will go up to 6 over time, so you can add a lot of wood ash at the
beginning. My native soil has a pH of about 5.5. Wood chips are about
0.2%P and 0.2%K, and of course no N, though if they have green branches
in there, they could have a bit. I have had some chips piles become hot
on their own, just due to the green bits. Wood ash is about 50%Ca, and
about 2%P and 7%K. Both chips and ash are rich in the other
micronutrients.

One thing to remember about wood ash is that you never apply it during
the growing season, as it may burn the plants, and as you say it is
much better if you apply it to organic matter before spreading such
organic matter. That will buffer it some. Also, check the optimal pH
for the plants. Wood ash is death for blueberries, but is good for most
plants, and great for specific vegetables or for irises for example.

In my case, I spread about 1lb for 20 sqft in late winter, or twice
that if there are wood chips already there. 1lb/20sqft is what you may
consider your maximum. In my case, given the native soil and nature of
the organic matter in the beds, I find that it takes one application if
the soil in the beds is from mixed compost (mainly leaves and manure)
sitting on top of the native soil, to take the pH to 6.5. If the
compost is mostly from wood chips, I find that it takes three
applications.