On 10/11/12 3:43 PM, Peter Jason wrote:
In very dry areas, is it possible to bore a
2-meter hole and plant a tree at the bottom?

The roots are nearer water this way and the hole
will collect any scarce rainwater.

The tree will etiolate upwards into the light
where normal growth will continue.

What do you think?


If there is a rare heavy rain or if the surrounding land drains towards
or near the hole, the tree will drown. I know of a group of Japanese
ornamental cherry trees, some of which were planted in shallow basins.
They are dying from root-rot.

Plant your tree on a slight mound.

If you can bore a hole 2 m deep, make 4-6 of them about 8 cm in diameter
in a circle around where you want to plant your tree. Get 2 m lengths
of 8 cm plastic pipe, the kind used for drains. Starting about 10 cm
from one end, drill 2 cm holes around each pipe. Place each pipe in a
hole in the ground with the undrilled 10 cm at the top. Fit a grate
over each exposed pipe end to prevent the pipe from filling with leaves
and other debris. Use these pipes to irrigate your tree by filling each
pipe with water once a week.

If the water table is 2 m down, eventually the tree's roots should reach
it. After 3-4 years, reduce the frequency of irrigating. If the tree
does not show any stress, the roots have indeed found the water table.
You might then be able to stop all irrigation. Leave the pipes; they
will permit air to enter the soil, which is good for healthy trees.

Note that all this will not work only if the tree is a type that has
only shallow roots that cannot reach the water table. Oaks, conifers,
and many others develop tap roots that will succeed in finding the water
table. But many of these are sensitive to excess water that would fill
a 2 m planting hole.

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