" writes:

You probably have every thing you need in your kitchen and/or laundry
room. Take a gallon of vinegar mix in a cup of salt and a half cup of
dish detergent. Mix it up and spray it on a nice day with no rain in
the forecast. You will notice it to start dying in a couple of hours.
In a day or two it will all be dead. That is what I do and it works
great.

I don't think salt is a good idea:

http://homeguides.sfgate.com/rock-sa...nts-56853.html

Soil Changes

A major problem with using rock salt even in small concentrations is
that is tends to stay in the soil for years until water leaches it
out. The salt raises soil salinity, which dehydrates the roots of plants
and keeps them from absorbing necessary nutrients. If you add too much
rock salt and it begins to affect plants you want to keep, as well as
ones you want to kill, start watering the plants deeply every day to try
to flush the salt out of the soil. You might not be able to save those
plants, because it could take months of daily watering to return the
soil to a viable salinity, but you can restore the soil so that new
plants can grow.

Where to Use It

Salt doesn't always stay where it's put -- it can be washed off into
your flower bed or lawn, killing large swaths of plants you want to
keep. Some salt-tolerant plants such as the bigleaf hydrangea (Hydrangea
macrophylla) can survive a bit of runoff, but not a full concentration
of rock salt applied nearby. Apply the salt on a day with no chance of
rain to let it soak in where you want it without the possibility of
runoff. The best places to use rock salt are those where you don't ever
want plants to grow, such as cracks in your driveway or along fence
lines.

--
Dan Espen