On Tue, 11 Jan 2011 09:30:04 -0800, Billy
wrote:

Where are you?

I'm in the Sacramento area. Winters are cool and rainy, with
occasional frost; Summers are hot and dry.

What is the soil like?

Generally deep, fairly heavy loam left by an ancient sea bed; but our
yard is heavily landscaped, and I don't know the history of the soil
that was used for fill. It looks like the native soil but I can't be
sure.

What kind of grapes are these?

When we moved in two years ago I collected samples from each vine and
took them to one of our local Master Gardeners (part of California's
ag extension program). I got some identifications, some tentative
ones, and some of "Gee, that's interesting, but..." Almost every vine
seems to be different. I can't find my notes at the moment, but the
ones I'm working on now appear to be wine grapes.

...if the vines are on rootstock?

No idea. I see no evidence of grafting scars, but I'm not sure what to
look for, and perhaps the vines are too old for them to be visible.
Many of them are over an inch thick at the base.

What did the leaves on the dead
plants look like last year, or the last year that they had leaves?

I think they were long dead when we bought the property two summers
ago. The vines are so tangled together that it's hard to tell which
ones are dead and which ones aren't. The one I mentioned, at a corner
of the shed: I suspected it was dead, but I wasn't sure until I
started cleaning up dead wood a few days ago.


Songbird wrote:

can you describe things further? (how many,
what kind, how they are arranged, spacing,
what kind of support, setting, sunlight, water,
etc?)

There are a lot of vines, almost every one a different variety, as I
mentioned above. Most of them are planted along the side of an arbor
covering a path about 50 feet long, which goes gently downhill in a
generally southerly direction. Most of those are in full sun (at least
at the top) through much of the day, but are shaded in the late
afternoon. Last year I put them on a drip irrigation system with a
couple of emitters near the base of each vine. They're on their own
branch of the drip system, so that I can water them infrequently and
deeply. The year before that, and probably many years, they received
no water at all except for the winter rains.

One vine (the only one producing heavily to date) is a seeded table
grape, Concord I think, which grows up a wall facing generally
northeast, over the top, and down the other side. (It also grows into
the surrounding trees, over 20 feet above the ground, which poses an
interesting dilemma: the higher vegetation does not appear to be
bearing much fruit, but I wonder if it is providing energy to the rest
of the vine, and should be retained.)

it can vary by variety, but generally first
year growth will be the smallest and smoothest
canes from the tips (where the leaves have died)
back to where they join with another cane. they
might even still be green and flexible.

One thing I've discovered, to my distress, is that much of the dead
wood is still flexible! That has made it very hard for me to be sure
what's dead and what's not.

By the way, I've wondered whether the thicker stuff I cut would make
good kindling.

the other thing to look at is the tendrils
that hold the vines to each other or the
support structure.

That's odd, now that I think about it: so far I've encountered very
few tendrils. That may be a peculiarity of the variety(ies) I've
worked on.

...or even posting pictures

That's a good idea, and I'll do it within the next few days. Can you
give me a general idea what kind of pictures would be most useful?

the other half i would only trim out the
obviously dead stuff and perhaps a few of
the more complicated tangles (to simplify
things for the next season).

Yes, that's along the lines I was thinking... if for no other reason,
because cleaning up a dozen vines would be overwhelming, even if I
knew what I was doing! Treating each half of each plant differently is
difficult, though, when I have trouble being sure where one plant ends
and another begins!