Winegrowers Supplies - Trellising
After laying the black plastic mulch you can then put the posts/stakes in; even before inserting the vine support poles and rabbit guard nets.
For larger vineyards, galvanised steel posts can be used. These have a very long life and have built-in slots for the wires, saving time and money in not having to hammer in hook-nails.
Kiln-dried and tanalised wood stakes are very good in the long-term (up to 50 years). Most of us have not had them kiln-dried so some posts start to break at ground level after 10 years or so, which is very annoying.
Intermediate wood posts/stakes are usually 8 feet (2450mm) long, 3" to 4" top diameter. They are knocked 2' 6" (750mm) into the ground, with one post every 4 vines; the posts are always positioned halfway between vines. In my larger vineyard I hired a 360-degree tracked-excavator to push down on the top of the posts, whilst I held a 1700mm baton alongside so the operator could see the height to stop. The tracks straddle the vine row, so this has to be done with the support canes removed (either before they are inserted initially or the following winter after pruning).It's normal to use large (4" to 5" inch diameter, 9 foot long) kiln-dried and tanalised wood posts for the row end posts. You can use galvanised steel ground anchors wired diagonally to the top of end posts or a Lintel system (2 posts 1 vine apart with a wood D-shaped lintel across the top, and a very strong diagonal bracing wire) as I do. In Germany they use a single long end-post and drive this in at an angle (about 25 degrees) so that the ground anchor is vertically below the top of the post, this avoids the problem of people tripping over diagonal wires but has the disadvantage of requiring different lengths for the moveable wires with chains.
Wire heights: there are many small variations on the wire heights, according to whether the fruiting canes are bowed and how high the top of the posts are above ground, assuming this is 1700mm and the top wire is at 1650mm:-
I suggest the single main wire (with Spannfix wire strainer
about 600mm in from the end post) at 1100mm above soil level; the vine support pole is clipped to this.
I also have a lower single wire (with Spannfix wire strainer about 600mm in from the end post) at 550mm above soil level; this is not essential but after about 4 years when the vine stock has reached 20mm diameter I use a special clip to secure the stock to the wire.
The first upper pair of moveable wires (one each side of the posts, with a chain at each end of the wire) is 250mm above the main wire. The second upper pair of wires is 550mm above the main wire. When the shoot growth is around 500mm the lower pair of wires can be unhooked from the hook-nails, pulled outwards and downwards to go under the growth, then carefully raised and put back on the hook-nails; ideally two people do this simultaneously the first working one post ahead of the other. The upper pair of wires can be handled similarly later in the growth season.
For the moveable wires the hook-nails should be hammered in to
the intermediate posts at about 45° to the wire direction, leaving about an
inch sticking out, so that the wire can't lift out when the wind blows or
when the slope of the land is concave.
I also use hook-nails for the single fixed wires, hammering them (at 90° to the wire direction) almost right in but allowing a 1mm gap so the wire can slide as it expands and contracts, and as the wind blows the foliage around. The big advantage over staples is that the hook-nails are square steel so don't split the wood as much as staples do, also they have a greater life. They are also longer and have a slight ripple on the steel so don't pull out as easily.
A leaf-wall of 1100mm high is ideal, which means topping the vine-hedge at about 2100mm above soil level, 450mm above the top wire.