Re: Decomposed granite as a mulch

Carolyn Stone wrote:
> 
> I have some decomposed granite left over from path-building and I want to
> mulch an iris bed to deter weeds.  Would it be a good idea to use the
> granite for that purpose?  Any advice will be appreciated.

Carolyn
Stone mulches are appreciated by many plants (They are very good at
retaining moisture as well as weed suppression) and the flag iris group
often grow naturally in stony place, though on limestone rather than
granite.

I don't think this would matter in the least though, provided your
irises are dressed occasionally with some lime or dolomite. You could
simply scatteer this over the gravel at whatever time of year you expect
rain and let nature wash it is for you.

One thing however I think you would need to watch is that you do not
pile mulch over the rhizomes so they lose the baking in the sun they
need over summer if they are to flower well.

I am quite a fan myself of stone mulching and for instance have my two
citrus trees covered right over their root zones with large beach
pebbles. These are great water-collectors in dry times causing
condensation of the minutest traces of dew or drizzle which then
trickles down to the roots, and then as well  protecting this moisture
from evaporation over the daytime. 

Some may wonder how one can feed such plants, we do actually sprinkle
some grass clippings on top of the pebbles and depend on worms to carry
them down, but as well we lift the pebbles about every second spring and
put a new layer of about a couple of inches of compost on the surface
beneath.

This is enough food to produce excellent growth and crops from an NZ
grapefruit and a Meyer lemon without any supplemntary supplies. I think
part of the success is due to the roots zone being kept cool all summer
so there is practically no loss of OM by oxidization.

Moira
-- 
Tony & Moira Ryan
Wainuiomata NZ, 
where it's Summer in January and Winter in July.
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