You need to apply just enough gypsum to coat the soil, about 1/8 to 1/4
inch thick.

In my garden, I hand broadcast gypsum. I treat my entire garden --
front and back - every other year, using about 250 pounds. (50 pound
sack costs about $9.) In certain areas -- especially around my
camellias and azaleas -- I use it every year. I use it because my soil
is heavy clay, and gypsum causes the clay to become less pasty and more
granular. That is, it improves the drainage and prevents the clay from
becoming soggy. I generally apply it in October or November,
anticipating the rainy season (November through March) to rinse it into
the soil. I also dig it into the soil when planting. Counting the
footprint of my house, I have slightly less than 0.2 acre (a standard
tract lot).

DO NOT buy gypsum at Home Depot. Their gypsum is only 70% and contains
pebbles and other non-gypsum trash. It's garbage!! I generally look
for a brand called Bumper Crop, which is 90% gypsum. Many nurseries in
my area carry it.


On 6/15/2014 5:24 PM, ElCuartoMago wrote:
They've been growing in a very wet area for the nearly 20 years.....
not a "swamp" but it is a flood zone.

I'll try bringing in some gypsum but I have to be careful. It's a
very wet and you can't really bring equipment in. it would have to be
hand trucked (wheelbarrow). is there a suggested cubic yardage/square
yard that I should be targeting?

I've already moved a great deal of the debris (mostly like a river
river sand and many many rocks). the surface roots makes sense as the
above (i'm guessing) might have have suffocated the surface roots in
that area.



--
David E. Ross
Climate: California Mediterranean, see
http://www.rossde.com/garden/climate.html
Gardening diary at http://www.rossde.com/garden/diary