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secondspring

Question about greenhouse tomato trellising

secondspring
9 years ago

Hey everyone,

This will be our first year growing tomatoes in a summer greenhouse. I've read quite a bit about how to trellis them to a post-and-wire system--the kind in which a wire is suspended above the tomatoes and running the length of the bed, with polypropylene twine dangling from the wire for the tomatoes to climb--and I have a couple of lingering questions.

Our greenhouse is more of a mobile tunnel: it's just ground-anchored PVC with rigidity coming from rope tied between the hoops and staked to either end of the tunnel. So, there's no solid structure to which we might attach the wire that runs above the tomatoes.

I've read that it's possible to use heavy duty posts with a turnbuckle. My questions are:

1) What kind of post exactly? Everything I've read says "sturdy metal posts," but that's pretty vague. If someone could point me to exactly the right kind of post I need, that'd be really helpful. Would some kind of wood work just as well? We may have some scrap 4x4 posts lying around. Keep in mind that our beds are 35 feet long, and will need to support 35 tomato plants.

2) How can we attach the wire to the turnbuckles, and then to the post?

3) What gauge wire is recommended? I've not been able to find an explicit number online.

Thank you all in advance for your help--I need to get the trellis in the next couple of days, as the tomatoes are in need of something to climb.

Comments (13)

  • cole_robbie
    9 years ago

    Standard farm fence posts are "T-Posts." I put a picture of them below. They come in different lengths. You'll want a post driver, which is a metal tube that slides over the top of the post.

    String is cheaper than wire. I use sisal string. There are multiple ways to trellis. I like using 2x4s and screwing a section about 2' long to the post perpendicularly. I sandwich two boards over the post and screw them together. Then I drill 3 holes, and run string through each of them. As the plants grow, I'll add another set of three strings above them.

    My high tunnel plants are trellised on cattle gates hung from T-posts. I like the gates a lot better than string, but they are a little pricey.

    Here is a link that might be useful:

  • 2ajsmama
    9 years ago

    With a PVC hoophouse, I'd go with the T posts and cattle panel (I used CRW, comes in 150ft rolls but if you only need 35ft then I'd get two 16ft CPs and do 32ft, maybe leave the 3ft gap in the middle so you can walk between, if you already have space at end of bed to walk around). I've done that out in the field.

    OR...Jay (jrslick) uses wooden stakes and FL weave, you could weave on T posts too and might be able to do 1 post every 3 plants. I don't like the sisal b/c it stretches (and degrades out in the weather) - the poly baling twine is better. I'm thinking of this method in my new HT.

    I'd also space the plants 2ft apart (18" if the soil is really good and the bed is wide) instead of 1 ft apart. Just don't prune to a single stem like you would for the vertical string, you'll still get as many tomatoes with 2-3 stems per plant as you would with 1 stem and 2x the plants.

    Search for jrslick tomato pictures and you'll see how nice and bushy his are, I don't know how many stems he prunes to. Oh, and he grows determinates (so maybe he doesn't prune at all).

    This post was edited by ajsmama on Tue, May 20, 14 at 16:03

  • jrslick (North Central Kansas, Zone 5B)
    9 years ago

    You can come and find out how many stems I prune too, I need to start doing it this weekend! :)

    Since this is inside, I would weave them. Much less cost involved. I plant mine in double rows the rows are 18-20 inches apart and the plants are 24 inches apart in each row. We grow determinate and Indeterminate plants and use the same system. We just have longer stakes for some of them!

    I usually prune the suckers off the indeterminate up to the first flower cluster and after that I forget about it. I am usually too busy to do it much after that. I also prune off the lower suckers on the determinates to ensure good airflow around the plants.

    I place a metal T post at each end and one in the middle of each row. Then I drive a 2 by 2 wood post between every 3 or even 4 plants. Outside I do every two or three.

    Some outside plants with 4 foot stakes (had lots of issues with BER very early in the season)

  • 2ajsmama
    9 years ago

    Jay - could you pop in on my HT construction thread? Trying to figure out what connectors to buy to attach purlins to hoops. Don't really want to use the 1" conduit clamps like original owner did (make more holes). But crossover connectors look expensive - jaderloon may have best price. How did you attach yours?

  • secondspring
    Original Author
    9 years ago

    Thank you all for your input. But, I'd really prefer to try to wire and twine method I'd originally described. I like the idea of being able to train the tomatoes up to the wire and then laying the pruned bottom part of the stem down along the ground, so as to maximize growth and production (I've read that tomatoes can reach 10 feet or longer with this approach).

    Could anyone answer my original questions? Thanks,.

  • 2ajsmama
    9 years ago

    Well, I've seen someone grow in slit-open bags of Miracle Gro under a CP hung horizontally with strings coming down from it but they had a sturdy structure to support it all.

    Maybe Cole_Robbie can post a photo of the T Post setup described in his first post.

    I had tried to build a trellis with 4x4 posts outside, forget the spacing will have to look but turnbuckle and 14g wire - couldn't get 1 post in deep b/c of ledge, and both it and the one opposite it starting pulling in toward the middle, even with steel stakes and guy wires. I abandoned that idea (ground also didn't drain well) started using those wires to hang deer netting, I'm going to build up the beds sometime and plant blueberries there.

  • 2ajsmama
    9 years ago

    Sorry to hijack but Jay with double rows how do you weave and harvest from the inside? I'm thinking of 4 ft wide bed in center of HT for double row of tomatoes but now I'm wondering if two 2ft beds with maybe 1ft between would be easier?

  • randy41_1
    9 years ago

    i've used steel fence posts outside to trellis tomatoes. the posts have a hole in the top you can pass the wire through. the posts are 6'. they have a point on the end and a shoe (the flat piece of steel that stabilizes the post). you can't tension the wire as it will pull in the end posts like ajsmama says. the wire can be in the 10 gauge range. something you can easily bend and twist by hand. when the plants get fruit they will pull down on the wire and tension it as well as pull in the end posts. no problem though. i attach the plants to the wire with tomato twine and vine clips. no reason why you can't do this inside. if you have a way to brace the end posts you can tension the wire.

  • cole_robbie
    9 years ago

    I think you can tension a T-post if you run a wire to a ground anchor behind it from the top of the post, and then also tension that wire.

  • jrslick (North Central Kansas, Zone 5B)
    9 years ago

    Here is a double row. You can easily pick from the inside as the plants are two foot apart in the row. I weave the plants as long as I can and then I just add some string on the outside and "Cage" them between the two posts. They basically form a tomato hedge.

    You can put more plants in the same space doing it this way and they have the same amount of space.

    Jay

    This post was edited by jrslick on Wed, May 21, 14 at 12:04

  • 2ajsmama
    9 years ago

    So do you zigzag the twine between the 2 rows or weave each row independently? How wide is your plastic? Looks like plants are offset, so I don't know if it's 2ft on diagonal or 2ft going perpendicular to the edge of the plastic from plant to plant.

    It just looks to me like it would be hard to get in the middle without breaking some trusses. I could theoretically reach into the middle of a 4ft wide bed since I'm 5ft 2 but standing and reaching between plants (esp trying to weave) might be a problem, that's why I'm thinking a narrower bed or separate rows might be easier?

  • jrslick (North Central Kansas, Zone 5B)
    9 years ago

    Each Row is weaved by itself. Then as they get bigger, I just weave a string on the outside of the bed to keep them contained and out of the aisle.

    The plants are offset. In one row I have plants at 1, 3, 5, 7, 9 etc... and the other row is at 2, 4, 6, 8, 10 etc...

    The plastic is 3 foot wide. That is what I use on my mulch layer. We have 7 beds in this building with 14 rows. 4 foot plastic would be better with this set up, but I use what I have. There are two runs of drip tape under each bed.

    Reaching to the middle of the bed is not a problem. The bed is only 3 foot wide. Doing this is a better use of resources and valuable space.

  • 2ajsmama
    9 years ago

    Thanks, so I will rethink my 4ft bed, maybe I can even fit 4 beds instead of 4 in the 13.5ft wide HT.

    To the OP - I just measured, my 4x4s are 7ft apart in width but 20ft apart the length of the rows. 14g wire pulled through eyebolt in top of post with tensioner between eye and stake so guy wire and trellis wire is all 1 length. The posts pulled toward the middle of the row. Maybe making separate guy wires attached to the posts would be better?

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