Building A Trellis for Indeterminate Tomatoes
In this article, we cover selecting the proper wire cable diameter based on the number of plants you will be growing and show our best practices for anchoring cables to your hoop house.
Trellising indeterminate tomatoes allows vines to grow vertically, which aids in cooling the vine and promotes healthy fruit sets. It also allows the farmer to efficiently maintain and harvest crops throughout the growing season while keeping the house’s pest and disease pressure to a minimum.
Build what your crops need and avoid choosing the cheapest option. Tomato plants get heavy! The last thing you want is to come in one morning to find a whole row of tomatoes has fallen to the ground.
Determining the trellis wire cable diameter you need to support your tomato vines.
Depending on the size of your hoop house and the number of plant sites per row you plan, you will need a different diameter of wire cable. In the formulas below, we assume that you will be spacing your plants at 18” intervals within rows. These formulas also assume 10 pounds of weight per vine. If you will be using a different spacing within rows for your plants or will be growing a heavier crop, adjust these two variables accordingly.
Below, we have done the math for you on common hoop house lengths. If your house is a different size or you wish to adjust the variables mentioned above, you can set up your own equation using this formula.
In all of our equations below, we have assumed 6’ of end wall working room. This allows you 3’ on either end of the row to wrap the vines around and continue the racetrack. If you need more space for your own comfort or other factors inside your house, adjust this amount.
Tomato vine weight and length formula
Hoop house length in feet - end wall working room x 12” / 18” = # of plant sites
( # of plant sites @ 18” on center) x 10 pounds = Total MINIMUM weight to support
Trellis wire cable diameter recommended for common hoop house lengths.
20’ hoop house
6’ end wall working room = 14’ of row space X 12” = 168” / 18” spacing = 9.33 plant sites ≅ 10 X 10 lbs. of vine weight = 100 lbs. working weight
Conservative working wire = 3/16”
Budget working wire = ⅛”
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40’ hoop house
6’ end wall working room = 34’ of row space X 12” = 408” / 18” spacing = 22.67 plant sites ≅ 23 X 10 lbs. of vine weight = 230 lbs. working weight
Conservative working wire = 3/16”
Budget working wire = ⅛”
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60’ hoop house
6’ end wall working room = 94’ of row space X 12” = 648” / 18” spacing = 36 plant sites ≅ 10 X 10 lbs. of vine weight = 360 lbs. working weight
Conservative working wire = ¼”
Budget working wire = 3/16”
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80’ hoop house
6’ end wall working room = 74’ of row space X 12” = 168” / 18” spacing = 49.33 plant sites ≅ 50 X 10 lbs. of vine weight = 500 lbs. working weight
Conservative working wire = ¼”
Budget working wire = 3/16”
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100’ hoop house - 6’ end wall working room = 94’ of row space X 12” = 1128” / 18” spacing = 62.66 plant sites ≅ 63 X 10 lbs. of vine weight = 630 lbs. working weight
Conservative working wire = ¼”
Budget working wire = 3/16”
What kind of wire cable should I use to build my tomato trellis?
We recommend using 7/19 304 galvanized stainless steel cable. This is often called aircraft cable. It is made up of seven strands of wire, each composed of 19 individual strands. It is quite strong and corrosion-resistant, which is crucial in a humid hoop house.
The equations from the above section will determine which of the many available diameters of this cable you will need to support your growing vines.
Attaching vines to the trellis wire
We recommend the Qlipr Trellising System, which works well with our Truss Kit.
- The metal hooks come in various sizes to fit your setup. They're stainless steel and reusable each season.
- The clips are lined in soft foam, gentle on your plants.
- Use this system quickly and easily with the lower-and-lean method.
Framework for supporting trellis cables in the hoop house
The following framework can be used to build attachment points for each row of trellis wire. It is up to you to decide if your existing frame is strong enough to support the additional weight or if you need to beef up your internal framework. The construction outlined below by Nick is based on the All-metal Hoop House kits designed and sold by Bootstrap Farmer. These kits include four-foot ground posts sunk two feet into the ground. They have been designed to provide enough pulling support to attach this kind of trellis system.
A 1” piece of square tubing is used as a horizontal support bar. This support bar will be attached as shown below. Your trellising cable is then attached to these using eye bolts and 6” turnbuckles with hooks. The black hexagons represent the attachment points where the square tubing connects to the four end-wall uprights.
The smaller grey hexagons represent the anchor points for each row of trellis wire. Depending on the size of your hoop house, you may need to place the horizontal bars higher or lower than pictured here. Because the tubing is attached to the inside of the uprights, there will be over an inch of space between the plastic and all of the attachment hardware to prevent rubbing.
Working from the inside edge of your house, the order for each row assembly will be:
- Eye bolt nut (put a little lock-tight on it)
- Square tubing
- Eye bolt
- Turnbuckle with hooks
- Looped wire with clamp-down anchor
HOOP HOUSE END WALL VIEW
SIDE VIEW OF TRELLIS LINE
OVERHEAD VIEW OF TRELLIS LINE
Following these outlines and equations, you will be able to build a strong trellis system that will last you for years if properly maintained. Build the best system you can afford and keep in mind that most of the expenses in installing this type of system will be one-time costs. If you have questions, please email us at contact@bootstrapfarmer.com. We are always happy to help you design a system that will work for you.
Adapting a tomato trellis for outdoor use
Use t-posts to adapt our trellising system for outdoor plants, using the methods outlined above. The t-post will replace the square tubing and provide a place to hang shade cloth should you need it in your area.
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