What Gauge Wire for Trellis?

Is 12.5ga high tensile wire sufficient for trellising blackberries and muscadines? Posts would be set 20ft apart. Total length 150ft. This is what’s available locally at TS. Breaking load is 1,500lb.

I could order 9ga if that’s what’s really needed for the muscadines. I can’t imagine blackberries needing more strength, but not sure about the grapes. Thanks

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Grape will be a much heavier load on trellis than blackberries, Blackberries require side to side support while the canes hold them up vertically. Grapes need vertical support for their entire weight. More stands of wire can be used to support grapes rather than thicker wire. a 20 pound load on a tight wire may stretch the wire at 400 pounds depending how taught the wire is at 0 pound load.


My heaviest bearing grapes (cayuga, vidal) put 1000-1300 lbs on 300 feet of trellis, so 12.5 gauge should be ok. That’s on an umbrella system where realistically some of the weight is passed onto the middle training wire.

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All my fruits don’t come close to that weight.

It’s a small commercial block I take care of, a friend sprays it and I do the handwork with some part time help in the summer. I have probably picked that amount in the fall using most of a day.

I can’t say what one would need but can say the heavier the wire the harder it will be to work with. I much prefer the larger gauge wire. Much easier to twist or tie down.

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9 gauge is the size recommended for muscadine trellises. I use and prefer the barbless wire. It appears to be strong enough to support an annual 50-60 pounds of fruit plus the huge vine. Post spacing is an important factor on the load a wire can carry without sagging.

So, I’m trying to find the wire locally, but I’m having a hard time finding high tensile wire. I’m assuming that any wire that doesn’t specify high tensile probably isn’t. My question is, can I substitute a thicker gauge regular wire for grapes? For example, could I use a 9 ga wire in place of 12.5 ga high tensile?

I know I can mail order the high tensile stuff, but so far I’m finding either rolls that are way bigger than I need, high shipping prices, or both.

I add t-post about every 10’ and use a smaller wire (barbless).

I bought this spool of 2000ft for $100 and its a bear to work with.

With 2 sets of pliers i cant hardly bend it and i had to bring out some really heavy duty cutters to cut it. I have no idea how im going to attach it to T-posts on the ends. You cant wrap it… its too dang strong. I can see where it could be nailed to a wooden post…but no clue how to attach it to T-Posts.

I had to build a make shift cage to hold it while i cut the binders…it goes haywire when you work with it.

Says the breaking strength is 1500lbs and i believe it.

anyone worked with this on t-posts?


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One Way Anchor Vise Grape Trellis Coated Wire Tightening Vice 12.5 Gauge 10 Pack https://smile.amazon.com/dp/B00BB0D3IO/ref=cm_sw_r_cp_api_glt_i_B9XW0P8JH6AXPHVPS7VG?_encoding=UTF8&psc=1

Some YouTube videos on setup. Need well anchored (deep set) wood end posts.


Not exactly an answer but with some more tools you should be able to get something done.

Crimping die-

Chain grabber/strainer/puller-

High tensile wire is a pain. Always stick an end in the dirt, wear safety glasses, and put one end under your armpit when you make a cut.

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Lol yes more tools always helps.

I have a barb wire fence stretcher and that seems to work… i thought about drilling a hole in my T-Post and while its stretched feed it thru the hole, then quickly crimp it with a pair of vice grips until i can get it more permanent.

The one way anchor vice seems to be the smartest idea.

@jcguarneri the hole drilled and feeding the wire through was going to be my suggestion. I’d make sure it is painted again once drilled just for looks, you might even try to make a rubber grommet for the hole, possibly try using a piece of automotive hose?

I was also going to suggest ratchet straps or a come along to tighten the line but it looks like similar tools have been suggested already. I’ve used wire rope clips for a similar but lower strength situation in the past.

This is kinda probably what i might do.

May I suggest a different method of tensioning wire for a trellis? This is the tool that I used for each of the high-tension wires that I used when I built my first muscadine and raspberry trellises, and the same one that I will use for my new ones.



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