Indeterminate tomatoes grow 6 feet or taller and need sturdy support; determinate types stay near 4 feet. Enter how many plants you are growing and your support style below to estimate the posts, string, stakes, twine, or cages you need to buy.
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What your result means: the estimate lists the main materials for your chosen support style so you can buy the right amount in one trip. Add about ten percent for waste and ties.
How do you use the trellis calculator?
Enter your plant count and spacing, say whether your tomatoes are tall vining or short bush types, then choose a support style. The calculator estimates the main materials.
- Enter plant count and spacing in inches between plants.
- Choose variety type, which sets the support height.
- Choose a support style and press calculate to see the materials list.
What each result means
| Result | What it tells you |
|---|---|
| Row length | Total feet your plants occupy, the basis for every estimate |
| Posts / stakes | The vertical supports to drive into the ground |
| String / twine | Length of line to buy for tying and weaving |
| Cages or fencing | Number of cages, or fencing feet to build your own |
Which tomato support should you use?
The best support depends on how many plants you grow and whether they are tall or short. Long rows of indeterminate tomatoes favor a string trellis or stake-and-weave; a few plants or containers do well in cages.
| Support | Best for | Cost |
|---|---|---|
| String trellis | Long rows of indeterminate tomatoes | Low, most economical |
| Stake and weave | Market rows and many plants | Low to medium |
| Cages | A few plants, low effort, containers | Medium, reusable |
How does the calculation work?
The tool first finds your row length from plant count and spacing, then applies a materials rule for the support style you pick.
String: 2 end posts plus 1 every 8 ft; top wire = row length; string = plants times (height + 1)
Weave: 1 stake every 2 plants plus 1; twine = row length times 2 sides times about 6 passes
Cages: 1 per plant; or about 6.3 ft of fencing to build each
Support height is set by variety: about 6 feet for indeterminate vining plants and 4 feet for determinate bush types.
Worked example
Say you grow 10 indeterminate plants spaced 24 inches apart on a string trellis. Row length is 10 times 24 divided by 12, or 20 feet. That needs 2 end posts plus 2 mid posts (about 4 posts), a 20-foot top wire, and 10 strings at 7 feet each, roughly 70 feet of vertical string.
Factors that change your materials
- Variety height: tall indeterminate plants need taller posts and more string than short bush types.
- Spacing: wider spacing lengthens the row and adds posts and wire.
- Wind and site: exposed gardens need heavier posts set deeper.
- Season length: long seasons grow taller plants, so allow extra string height.
- Reuse: cages and metal posts last years, spreading cost over many seasons.
Understanding your outputs
| Output | Meaning | Best used for |
|---|---|---|
| Row length | Total feet of planted row | Sizing beds and buying wire |
| Post or stake count | Vertical supports needed | Shopping for T-posts or wood stakes |
| String or twine feet | Line to buy | Choosing a roll size |
| Cage or fencing figure | Cages to buy or fencing to build them | Deciding buy versus DIY |
When to use it
Use the calculator before the season starts, while planning your bed layout and shopping list, and again if you expand a row or switch support styles. Market gardeners use it to price a stake-and-weave row, while home growers use it to decide whether cages or a string trellis are cheaper for their plant count.
Common mistakes to avoid
- Undersized posts: a loaded tomato row is heavy; use posts at least 6 feet for indeterminate plants and set them 1 to 2 feet deep.
- Supporting too late: add trellises at planting, before roots and sprawl make it hard.
- Skimping on string: vining plants keep growing; buy extra so you are not short mid-season.
- Cages too short: a 3-foot cage is quickly outgrown by indeterminate types.
- Ignoring wind: tall string trellises need firm end anchors or they lean.
Accuracy and limitations
The estimate is a planning figure, not an engineering spec.
What it calculates accurately: row length and typical material quantities for each support style from your inputs.
What it does not account for: post depth and gauge, soil firmness, wind load, or how tall your plants actually grow. Buy sturdier materials for exposed or windy sites, and add about ten percent for waste and ties.
Methodology
Method: row-length materials estimate by support style. Inputs used: plant count, spacing in inches, variety height, support type. Assumptions: indeterminate 6 ft, determinate 4 ft; string posts every 8 ft; weave stake every 2 plants; about 6 weave passes; DIY cage about 6.3 ft of fencing. Rounding: row length and materials to whole feet or units. Edge cases: zero or empty plant count prompts for at least one plant.
Sources: Iowa State University Extension – Growing Tomatoes, Royal Horticultural Society – Tomatoes, The Old Farmer’s Almanac – Tomatoes. Last reviewed: September 24, 2026 · Reviewed by Aiza Anwar.
Frequently asked questions
How tall should a tomato trellis be?
Build supports about 6 feet tall for indeterminate tomatoes and 4 feet for determinate types, since vining plants keep growing all season.
How far apart should tomato stakes be?
For stake and weave, drive a stake every two plants, about 3 to 4 feet apart, so the twine holds the row upright.
Do determinate tomatoes need support?
Yes, a small cage or single stake keeps determinate tomatoes off the soil, which reduces rot and disease even though they stay compact.
What is the cheapest way to support tomatoes?
A string trellis is usually the cheapest for long rows, needing only end posts, a top wire, and vertical string per plant.
How much string do I need per tomato plant?
Allow about 7 feet of vertical string per indeterminate plant, matching the support height plus a little for tying.
Are tomato cages or stakes better?
Cages are easier and reusable for a few plants; stakes and string are cheaper and better for long rows of many plants.
How deep should tomato support posts go?
Set posts about 1 to 2 feet deep, deeper in loose or windy soil, so a heavy fruiting row does not lean or fall.
Can I reuse tomato trellis materials next year?
Metal posts, cages, and wire last many seasons. Replace string and twine each year, and clean supports to reduce disease carryover.
How many plants can one stake-and-weave row hold?
A single stake-and-weave row can run as long as your bed; add a stake every two plants, so a 20-plant row uses about 11 stakes.
Related tomato tools
Visit the Growing Tomatoes hub
This calculator provides general planning estimates, not an engineering specification. Choose sturdier materials and deeper posts for windy or exposed sites, and add about ten percent for waste. Spotted an error? Tell us here.