"W. Watson" wrote:
An irrigation line break caused a dawn redwood (9' tall) and a crabapple
(9') tall to lose their foliage in the heat of August (90F+) period. Intense
watering for two weeks brought almost all the foliage back on the crabapple,
and did a fairly good job on the dawn (meta sequoia). The dawn usually has
some trouble each August (we live 60 miles outside of Sacramento and August
has lots of 90F+ days). I generally spray it lightly for days during such a
tough stretch, and each year it comes back fine.

I was talking to a gardener about this and she offered that trees have
something like 1 main leaf and an auxiliary leaf, if the main dies the aux
takes over. Sometimes they have a few extra auxs. Does this translate into a
tree having two, maybe three lives if hit by a lack of water?

Your gardener obviously knows nothing about dawn redwood's growing
habits. Dawn redwood doesn't do well in dry soils. Actually it does
very well in areas that are too wet for most other trees. I have two
dawn redwood growing in a wildflower meadow that is always boggy and
they have doubled in size in the four years since I planted them...
one is now about 8', the other around 20'.

Crabapple prefers well drained soil, its prefered habitat is just
opposite of dawn redwood... I would not plant those two together...
you'd need to choose which one can live, and they definitely do not
compliment each other an aesthetically.