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 or galvanised wire, 2.0mm or 12 gauge (x30ft/10m)
- Turnbuckles (x3) – or some other means of tensioning the 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)
- Yellow lines indicate the position of the wire supports
- Red rectangles show position of turnbuckes
- Purple circles show position of fastening bolts
- Blue square shows position of plastic safety cap
Step 1 – 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.
Step 2 – Drill the star pickets to allow them to be bolted together
- Lay steel star-pickets posts on the ground, with the sides that have the holes facing inwards. This is important, as the wire will be strung through these holes when the trellis is assembled as an upside-down “U” shape.
- Hold flat edges against each other as closely as possible to work out where to drill the holes to bolt the posts together.
- Drill one hole at the top of each upright post, and drill two holes on the horizontal post – one hole near the top, and the other a short distance from the bottom (pointed end).
- Do not assemble at this point.
Step 3 – Drive star pickets into ground, the correct distance apart
The posts need to be hammered into the ground, the correct distance apart so they can be bolted together.
In firm soils, hammer the posts into the soil with a club hammer (small sledge hammer) if the soil is firm.
In loose soils that can’t adequately support the posts, dig holes of the correct depth and width (see below), then secure the posts in the holes using one of the following methods:
- Using gravel, set the posts into the holes, hold the posts straight, fill with gravel and pack it down around them.
- Using concrete, for an even more secure fixing, the posts must be held in place securely and straight until the concrete sets. To do this, use some kind of support, such as a teepee structure made of three timber stakes tied together at the top, then fill the hole with concrete.
How Deep to Dig Post Holes?
The general rule when setting fence posts or any other posts into the ground, is to have 1/3 of the total length above the ground, and 2/3 above the ground. Divide the height of the post by one-third, this is the depth of the hole required for it.
The simple way to do this is to divide the length of the post into three, the bottom third should be below the ground. So with a 180cm (6′) post, 60cm (2′) is in the ground, and 120cm (4′) is above the ground. If the posts need to be higher above the ground, longer pots are used.
How Wide to Dig Post Holes?
The general rule digging holes in the ground for posts is to make the post hole be 3 times the diameter or width of the post.
If the post is 10cm (4″) wide, the hole should be three times wider, which would be 30cm (12″).
- After the posts are in place, attach the horizontal post across the top by using the 6mm x 50mm with matching nuts and washers. Use the washers under the nuts to make it easier to tighten, and to prevent the bolts loosening.
In case the posts are too high, they can be driven deeper into the ground until the trellis sits at the desired height.
I drove the 2.4m (8′) posts 75cm (2.5′ ) into the ground, creating a 1.65m (5.5′) high trellis. Depending on the firmness of the soil, this will hold very securely.
As a further note, if this trellis is located at the edge of a raised garden bed, the vertical supports can be fastened or attached to the side of the raised bed for additional support.
Step 4. Attach 2mm wire through the holes of the inner edges of the vertical supports at the desired height
- Using plastic coated or galvanised wire, 2.0mm or 12 gauge in thickness, string the wires across the vertical pots of the trellis frame.
Note: If using turnbuckles, only attach the wire to one side only. If the turnbuckles will be placed on the left, only attach wires to the post on the right.
- Before using turnbuckles, wind them out to lengthen them, so they can be wound back in later to shorten them and tension the wire!
- Attach each wire to a turnbuckle, starting with the bottom one, working upwards, then turn the turnbuckes to tension the wires nice and taught.
Note: This step is optional but recommended, as small galvanised turnbuckles are quite cheap, and allow for very precise adjustment of tension on each wire.
What spacing should be used between wires?
- Wire spacing is really a personal preference, but a spacing of 30cm (12″) to 45cm (18″) between wires is a recommended distance for grape vines.
- Use three to four wires, with the lowest wire sitting approximately 60cm (2′) above the ground.
On the trellis I’ve built that is pictured in this article, the wires are spaced 45cm (18″ or 1.5′) apart from the bottom, leaving a shorter distance to the top. Looking back, spacing the lowest wire 60cm (2′) above the ground would have been much better.
Step 5 – Plant the grape vine and tie it to the wires of the trellis
Now that the trellis support is completed, the grapevine can be planted and the canes ties to the support wires.
For instructions on how to train and prune the grapevine in the following years, see article – How to Prune Grape Vines – Cane and Spur Pruning Explained
If you’re unfamiliar with turnbuckles, they’re devices for adjusting the tension on wire strung between two points.
Turnbuckles have either two threaded eyelets on each end, two hooks on either 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 three types of turnbuckles mentioned:
Note: When using the turnbuckles, wind them out first to lengthen them! Once they are wired in placed, then they can be turned to shorten them, and tension the wire.
- When using turnbuckles with two eyelets, fasten one end to the post with a short piece of wire, then fasten the long wire from the other post to the other eyelet.
- When using turnbuckles with a hook and an eyelet, the hook can be attached straight into the hole in the post if it will fit.
How to Tie Wires to Posts with a Haywire Twist and Barrel Roll
To fasten wire to the eyelets of the turnbuckles, or directly to the holes in the post, a secure way to do this is to use a method called a Haywire Twist and Barrel Roll, as detailed 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, use 3 to 4 barrel-rolls, I’ve found that to be sufficient.