Constructing a grape vine trellis is an excellent way to support your vines and ensure they receive ample sunlight for optimal growth. This guide will walk you through building a basic 2.0m x 2.4m (6′ x 8′) grape vine trellis, including the necessary materials and tools, and detailed construction steps. Let’s get started!
Materials Needed
- 2.4m (8ft) steel star pickets (x3)
- Plastic-coated or galvanized wire, 2.0mm or 12 gauge (30ft/10m)
- Turnbuckles (x3) or another tensioning method
- Bolts 6mm x 50mm (1/4″ x 2″) with matching nuts and washers (x2)
- Plastic safety cap for star picket (x1)
Tools Required
- Club hammer or similar tool to drive star pickets into the ground
- Drill with 8mm drill bit
- Pliers/wire cutters
Trellis Construction Steps
Step 1: Determine the Location for the Trellis
Orientation: For maximum sun coverage, position the trellis lengthwise from north to south. To use it for shade, position it to block the sun from the desired direction.
For example, to block the north midday sun in the Southern Hemisphere, place it in a northernmost position running west to east.
Step 2: Drill Holes in the Star Pickets
- Lay the star pickets on the ground with the sides that have holes facing inward. This is important, as the wire will be strung through these holes when the trellis is assembled as an upside-down “U” shape.
- Hold the flat edges against each other as closely as possible to determine where to drill the holes to bolt the posts together.
- Drill one hole at the top of each upright post and two holes on the horizontal post—one near the top and one near the bottom.
- Do not assemble the trellis yet.
Step 3: Drive Star Pickets into the 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)
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
Posts should be set with 1/3 of their length below ground and 2/3 above ground. Divide the height of the post by one-third, this is the depth of the hole required for it. For example, with a 180cm (6′) post, 60cm (2′) should be in the ground, and 120cm (4′) above ground.
How Wide to Dig Post Holes
The general rule for digging post holes is to dig the hole three times the diameter of the post. For a 10cm (4″) post, the hole should be 30cm (12″) wide.
Step 4: Assemble the Trellis
- Attach the horizontal post across the top using the 6mm x 50mm (1/4″ x 2″) bolts, nuts, and washers. Use washers under the nuts to ease tightening and prevent loosening.
- Ensure the trellis sits at the desired height and is level. Drive the posts deeper if necessary. In this example, the 2.4m (8′) posts were driven 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.
For additional support, if the trellis is located at the edge of a raised garden bed, the vertical posts can also be fastened to the side of the raised bed..
Step 5: Attach the Wire
Attach the wire through the holes of the inner edges of the vertical supports at the desired height. Note: The use of turnbuckles is optional but recommended, as small galvanised turnbuckles are quite cheap, and allow for very precise adjustment of tension on each wire.
- Use plastic-coated or galvanized wire, 2.0mm or 12 gauge in thickness, and string the wires across the vertical posts of the trellis. 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 turnbuckles to tension the wires so they’re nice and taught.
Recommended Wire Spacing
- Wire spacing is really a personal preference, though it’s recommended to space the wires 30cm (12″) to 45cm (18″) apart for grape vines.
- Use three to four wires, with the lowest wire sitting approximately 60cm (2′) above the ground.
Step 6: Plant the Grape Vine and Secure it to 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
Additional Information
What Are Turnbuckles?
Turnbuckles are devices designed to adjust the tension on wires strung between two points. Each turnbuckle has a metal body with threaded eyelets or hooks on each end. These eyelets or hooks can be configured in three ways: both ends with eyelets, both ends with hooks, or one end with a hook and the other with an eyelet.
One end of the turnbuckle has a left-hand thread, and the other end has a right-hand thread. By rotating the metal body while keeping the ends fixed, the threads move in opposite directions, allowing you to either tighten or loosen the tension on the wire. This makes turnbuckles an efficient tool for precise tension adjustments.
Pictured below are the three types of turnbuckles mentioned:
How to Tie Wires to Posts with a Haywire Twist and Barrel Roll
To securely fasten wire to the eyelets of turnbuckles or directly to posts, use the Haywire Twist and Barrel Roll method:
- Thread the Wire: Pass the wire through the eyelet or hole in the post.
- Form a Twist: Rotate the loop until a twist forms.
- Complete Twists: Make 3 to 4 complete twists.
- Create a Right Angle Bend: Bend the end of the wire at a right angle to the main wire.
- Form Barrel Rolls: Wrap the end of the wire tightly around the main strand 3 to 4 times to form barrel rolls.
For direct attachment to a post, 3 to 4 barrel rolls are usually sufficient.
Visual Guide to Trellis Construction
The picture below highlights the various parts of the trellis to assist in explaining the construction. (Click on the picture to enlarge)
- Yellow lines indicate the position of the wire supports
- Red rectangles show the position of turnbuckles
- Purple circles show the position of fastening bolts
- Blue square shows the position of the plastic safety cap
In conclusion, building a grape vine trellis enhances the support and health of your vines. By following these steps and ensuring proper tension and spacing, you’ll create a sturdy structure that promotes optimal growth and fruit production. Happy gardening!