personally I would just add enough t post so that it did not sag... how bad would it be if after 5 years of growing your vine the guide wire gave lol. also make sure your using real t-posts not the the el-cheap-o V-posts they sell at lowes and homedepot. t-posts are almost 1/4 steal bar that is solid. the v-posts are 1/8th inch bent sheet metal that do not have nearly the same strength

I'm in a very similar situation. I plan to anchor to a locust post set about 30 degrees off of vertical, extending about 12-15" out of the ground, and set at least 36" deep.

Do you mean end post anchors? Check the link for various types. I never used them, but if I did, i would probably use the earth anchor. I saw a Utube video of these being used for all things, a Kiwi trellis! I would still use these on a vertical setup. They did in the video too.

Here is a link that might be useful: earth anchors

This post was edited by Drew51 on Wed, Apr 17, 13 at 7:23

I used some earth anchors (the local hardware store referred to them as mobile home anchors) and they failed. All it takes is a few days of good hard rain to saturate the soil and they will come up under a load.
I pulled mine out. I ended up using eye-bolts set in concrete. Yes, it is more work, but it is stronger and you will be better off in the long run. Imagine your kiwi's mature and loaded with almost ripe fruit.

thomis,

Thanks for your input. I am in the same position and was ready to purchase Earth Anchors. FWIW, do you think they would be better in drier, rockier, and clayier soil, or just impossible to install?

"All it takes is a few days of good hard rain to saturate the soil and they will come up under a load."

That would not happen where I live because we have a heavy clay soil, and they would never give no matter how much is rained. If anything the rain would make them even harder to remove.

I myself use 1 inch diameter 10 ft (buried 4 feet), steel poles. They are bent, but the clay holds them firmly in place. I use wire tighteners if any slack occurs from the bend. I don't use any other support. They are not even cemented in, just placed directly in the soil. Again the clay will never let go of them.

This post was edited by Drew51 on Thu, Apr 18, 13 at 1:35

That's true, I didn't have them in clay. I have clay in some areas but I positioned the orchard over some friable loamy soil that used to be pasture.
milehighgirl, "do you think they would be better in drier, rockier, and clayier soil, or just impossible to install?"
Yes, I think they are hard to install in rocky soil, I remember having to abandon holes and start others when I encountered rocks. If its really dry perhaps you could wet it down good with a hose to make it easier to screw them in.
All that said, its still worth a look at the eye bolts in concrete. I will try and find a pic or two.

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That cemented anchor is awesome looking!! A great idea for heavy loads even in clay. I only need them for blackberries, raspberries and grapes (only 6 ft section with post on each side-so has a lot of support). If I were to grow kiwis, I would consider doing this.
Anyway those eye bolts in cement look prefect. How thick is the cement? Any rebar in those?

Yeah with clay my brambles are in raised beds or highly ammended soil. Same with my fruit trees. I only have a backyard to deal with. A small backyard at that! So I have very limited room. I just constructed 5 rasised beds, all different sizes, all next to each other.
I do also grow trees at my cottage where I own more property.

My farm is fenced with high-tensile wire. I suspect that 1/2 mile runs of multiple strands of wire under tension put more pressure on the end/corner posts than some wimpy grape or kiwis are gonna put on 'em. I don't, however, on most runs, crank the tension up to the 200 psi the wire is rated for - with electrification, I only need enough tension to eliminate 'sag'.
I don't use any concrete, and have only resorted to earth anchors on two occasions - and those merely because of special situations/sites that wouldn't accomodate what I describe below.

For ends/corners, I just set a substantial post - redcedar, black locust, Osage Orange, old utility pole - 2.5-3 ft in the ground. In the bottom of the hole, on the 'back side' - opposite the direction of pull, I place a large flat rock, and backfill the hole, tamping the replaced soil firmly. Then, just below ground level on the 'front side' of the post, I bury a 2-3 ft 'bedlog'/deadman brace.
You can see bedlog bracing and floating brace types at the site linked below. If you use only a bedlog, as they demonstrate, the post can, over time, rotate and lean (I learned this the hard way) - but if you put a flat rock at back of the post, in the bottom of the hole on the opposite side of the post from the bedlog, you'll largely eliminate post rotation or leaning due to wire tension.

No guy wires to trip over or mow around, no problems with frost-heaving or a big chunk of concrete that you have to dig out and dispose of if you decide to abandon or have a change of plans.

Here is a link that might be useful: bracing

Here is my set up, you can see the posts bend a touch, but I can pound them in more with a fence hammering device.
Since they are not cemented they can be removed and repositioned even. I don't ever see a need to do so though.

A different angle where you can see the end post is bent a lot, it has wire going in 2 directions, one is really pulling on it, but who cares what it looks like.

Nice set up there on the raised beds.
"No guy wires to trip over or mow around"
Yes, that is the only problem with using the anchors, I have to weedeat around the anchors.

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I love the cement idea as that seems like it would be more steadfast than either the earth or ground anchors - thanks for the suggestions!

Second question I had on the T-bar trellis is what should I use fo the uprights? I'm looking for something that will not decline for 20 + years in moist soil. Most large trellises I've seen used 4x4 lumber uprights. I was thinking about using the "plastic lumber" 4x4's to prevent replacement in 20 years when they start to rot/weaken below the soil line - anyone have experience with this? Are they as strong/sturdy as regular wood 4x4's?

I'm not familiar with the product, but I have yet to see anything plastic last very long. I could see it getting brittle and cracking, or crumbling. A good way to prolong lumber is backfill post hole with gravel, or even sand. I guess it keeps moisture out, and when wet dries quickly. It should also keep out roots and pests. I use steel, it should last a few hundred years. I like the steel conduit poles. The heavy duty gauge is expensive. The lighter gauge seems fine for small garden.