Here are the instructions for the construction of a basic 2.0m x 2.4m (6′ x 8′) grape vine trellis as shown below.
Construction materials required are as follows:
- 2.4m (8ft) steel star pickets (x3)
- Plastic coated galvanised wire, 2.0mm or 12 gauge (x30ft/10m)
- Turnbuckles (x3) – or some other means of tensioning wire
- Bolts 6mm x 50mm with matching nuts and washers (x2)
- Plastic safety cap for star picket (x1)
Tools required are as follows:
- Club hammer – or something else to hammer star pickets into the ground with
- Drill with 8mm drill bit
- Pliers/Wire cutters
I have highlighted the various parts on the picture below to assist in explaining the construction.
(Click on picture to enlarge)
- Determine location for trellis. Orientation should run lengthwise north to south if you want to maximise sun coverage and not shade out any adjacent garden areas. If you choose to use it for shade, position it to run lengthwise across the direction you wish to block the sun from. For example, to block the north midday sun in the Southern Hemisphere, place in a northernmost position running west to east.
- Drill the star pickets to allow them to be bolted together. Lay them on the ground, drilled edges of the uprights facing inwards (important, as this is where you will string your wire) arranged in an upside-down "U" shape, and hold the flat edges together as close as you can, and then work out where you need to drill them to bolt them together. You will drill one hole at the top of each upright, and on the start picket that sits horizontally, you will need to drill one hole near the top, and one a short distance from the bottom (pointed end). Do not assemble at this point.
- Drive star pickets into ground, the correct distance apart. I drove mine 75cm (2.5′ ) into the ground, creating a 5.5′ high trellis. Depending in the firmness of the soil, this will hold. If it is loose, you may have to pack it down around the vertical supports, if that is insufficient, you may have to dig holes first and fill with a firmer material, or concrete. As a further note, if this trellis is at the edge of a raised garden bed, you can fasten the vertical supports to the side of the raised bed for further support.
- Attach 2mm wire through the holes of the inner edges of the vertical supports at the desired height. (You can use spacing of 30cm/1′ from the top, and every 30cm/1′ below that, this will give you three wires, with the lowest wire sitting approximately 60cm/2′ above the ground). In the picture of the one I’ve built, the wires are spaced 45cm (1.5ft) apart from the bottom, leaving a shorter distance to the top. Adjust to personal preference. Attach each wire to a turnbuckle, starting with the bottom one, working upwards, to tension up the wires nice and taught. Note, if the ground is not firm enough, and you tension up the turnbuckles too much, especially the lower ones, you will pull the posts inwards, and loosen the other tensioned wires above.
- You now have a completed trellis. All you need to do now is plant the grapevine in the centre and train it across the trellis as it grows.
If you’re unfamiliar with turnbuckles, they a device for adjusting the tension on wire strung between two points.
Turnbuckles have either two threaded eyelets on each end or a hook on one end and an eyelet on the other. They are screwed into each end of the long metal body. One eyelet has a left-hand thread and the other has a right-hand thread. By rotating the metal body while the ends are fastened, the tension can be adjusted by causing both ends to be screwed in or out simultaneously.
Here are pictures of the two types of turnbuckles mentioned:
When using the type with the two eyelets, you fasten one end of the wire to the post, then the other end to the eyelet.
When using the type with the a hook and an eyelet, you can put the hook straight into the hole in the post if it will fit.
Tying the Haywire Twist and Barrel Roll
To fasten wire to the eyelets of the turnbuckles, a secure way to do this is to use a method called a Haywire Twist and Barrel Roll, as explained below:
- Thread wire through eyelet, then rotate the loop so that a twist forms.
- Complete 3 to 4 twists.
- Bend back the end so it makes a right angle bend to the main wire .
- Wrap the end of the wire into a series of 3 to 4 tight rolls around the main strand or standing part to form the barrel–rolls.
When tying wire directly to the post, you can simply use 3 to 4 barrel-rolls, I’ve found that this is sufficient.