On 9/19/10 6:31 AM, Dave_s wrote:

If the tree is dying ONLY of old age, not dying from GREENING DISEASE,
I might want to plant the new DWARF MEYER LEMON in the same location.
What should I do to the soil before planting the replacement tree in the
same location?

Remove it soon. That means digging out a hole about 4 ft in diameter
and 3 ft down. Fill the hole with a mix of native soil, compost, and
peat moss until the packed soil is level with the surrounding soil.
Then treat the hole with a soil fumigant (available in many nurseries).

Let the spot go fallow until next March before planting a new tree. A
newly planted citrus is going to send out new shoots quite soon after
planting. You are likely to see some night-time frost in the winter,
which might kill that new growth. Thus, you want to wait until the
frosts are past.

Just before planting the new tree, dig out the hole and place a generous
amount -- 2-3 handsful -- of bone meal or superphosphate in the bottom.
Stir that into about 3-4 inches of the soil at the bottom of the hole.
Place another few inches of unenriched soil on top of that. The
phosphorus in either fertilizer will promote flowering and fruiting.
Since it does not readily dissolve and leach through the soil, it must
be placed where roots will find it.

Plant the tree slightly above grade so that the packed soil is slightly
mounded. Citrus requires good drainage. Water should not accumulate
around the trunk.

Protect from snails, which love not only citrus leaves but also citrus
bark. I have several strands of bare copper wire wrapped around the
large pots for my dwarf lemon, orange, and kumquat. I have several
strands of the wire loosely wrapped around the trunk of my dwarf
tangelo, which is in the ground. Others use copper foil. Also, instead
of using snail bait, I have place carnivorous decollate snails in my
garden. (See http://www.ipm.ucdavis.edu/PMG/r107500111.html.)
However, it takes about three years for those to give good control
against the brown snails that are so destructive in southern California;
by that time, the brown snails can kill your tree by eating the bark all
the way around.

--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 21 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a, very close to Sunset Zone 19)
Gardening diary at http://www.rossde.com/garden/diary