String support works best when you tie it loosely around the stem and anchor it to a stake or overhead frame

String support is one of the cheapest ways to keep tomato plants upright as they grow. The method works by tying a loop of string around the main stem — loose enough that the stem can expand — and anchoring the other end to a stake driven into the ground or to a horizontal wire or frame above the plant. As the plant grows taller, you add more loops of string up the stem, usually every 8 to 12 inches. The string bears the weight of branches and fruit, not the stem itself.

This approach works well for indeterminate varieties (the ones that keep growing all season) because you can keep adding support as the plant climbs. It also lets air circulate around the plant better than cages do, which reduces disease. The main trade-off is that string support takes more time to set up and maintain than straightforward dropping a cage over the plant.

Key Takeaways

  • Tie string in a loose figure-eight loop — one loop around the stem, one around the stake — so the stem can move and expand without cutting off circulation.
  • Start tying when the plant is 12 to 18 inches tall and the first flower cluster appears, then add new loops every 8 to 12 inches as the plant grows.
  • Use soft, flexible string like twine or cloth strips rather than wire or fishing line, which can cut into the stem as it thickens.
  • Anchor the string to a wooden stake, metal rod, or overhead wire frame depending on your garden layout and how tall your variety grows.
  • Check ties every week or two during the growing season and loosen them if the stem is pressing against the string.

Choosing the right string and anchor point

The string itself matters more than most gardeners think. Soft twine, jute, or cloth strips work well because they give slightly as the stem thickens and do not cut into the plant. Avoid fishing line, thin wire, or anything stiff — these can girdle the stem (cut off the flow of water and nutrients) as the plant grows and the stem expands. Cotton string or old fabric torn into strips are cheap options that work just as well as garden twine sold in stores.

The anchor point depends on your setup. A wooden stake (usually 6 to 8 feet tall for indeterminate varieties) driven 12 inches into the ground works for single plants or small groups. For larger plantings, many gardeners run a horizontal wire or wooden frame above the row and tie string down from there, which spreads the weight more evenly. Metal stakes work too, but they heat up in the sun and can damage the stem if it rubs against them directly — wrap the stake with cloth or use a stake guard if you choose metal.

The figure-eight tie: the knot that does not cut

The figure-eight tie is the standard because it keeps the string from pressing directly against the stem. To tie it, loop the string around the stake or support first, then bring it across and loop it around the stem, leaving an inch or two of slack. The string forms a figure-eight shape when you look at it from the side — the stake is at one end, the stem at the other, and the string crosses between them without touching both at once.

This design matters because it lets the stem move slightly in the wind without the string cutting into it, and it gives the stem room to expand as it grows thicker. A straightforward knot around the stem alone will eventually strangle the plant as the stem thickens. Tie the figure-eight loosely enough that you can slide a finger under the string — if it is tight against the stem, loosen it.

When to start tying and how often to add new loops

Wait until the plant is 12 to 18 inches tall and has set its first flower cluster before you tie the first loop. Tying too early can damage the delicate young stem, and the plant is not heavy enough yet to need support. Once you tie the first loop, add a new one every 8 to 12 inches as the plant grows upward. For indeterminate varieties that grow 6 to 8 feet tall, you will end up with 5 to 8 loops by the end of the season.

Check the ties every week or two during the growing season, especially after heavy rain or wind. Loosen any tie that is pressing against the stem — the stem will have thickened since you put the tie on, and what was loose will become snug. A stem that is being squeezed will show a slight bulge above the tie and may start to look pale or discolored. Loosen it when ready if you see that.

String support versus cages and stakes

String support, cages, and single stakes each have different strengths. A cage is the fastest to set up but offers the least support for heavy fruit and can trap moisture inside, raising disease risk. A single stake is cheap and straightforward but works best for determinate (bush) varieties or for pruning indeterminate plants down to one or two stems. String support takes more time but gives you the most control — you can tie as many loops as you need, adjust them as the plant grows, and keep air moving around the whole plant.

Many gardeners use a combination: a stake or cage for the lower part of the plant for stability, then string ties higher up as the plant gets taller and heavier. This hybrid approach gives you the speed of a cage with the flexibility of string support.

Overhead wire systems for larger plantings

If you grow tomatoes in rows, an overhead wire or wooden frame saves time and spreads the weight more evenly than individual stakes. The frame is usually made from two horizontal wires or wooden rails running the length of the row, supported by posts at each end. String hangs down from the wire to each plant, and you tie the string around the stem using the same figure-eight method.

As the plant grows, you can either tie new string higher up on the frame, or you can spiral the same string around the stem as it grows, tying it off at intervals. The spiral method is faster once you get the hang of it — you tie the string to the frame once, then wrap it around the stem as the plant climbs, securing it with a loose knot every 12 inches or so. This system works well for indeterminate varieties and is common in commercial greenhouses.

Troubleshooting common string support problems

If the stem is bending or drooping even with ties in place, the string is probably too tight or the anchor point is not strong enough. Loosen the tie first — a stem that cannot move at all in the wind will snap more easily than one with a little give. If loosening does not help, the stake or frame may be undersized for the weight of the plant. Add a second stake or reinforce the frame.

If you see the stem bulging above a tie or the leaves above the tie are yellowing, the tie is cutting off circulation. Loosen it when ready and check it daily for the next week. If the damage is severe, the plant may not recover that part of the stem, but loosening the tie will save the rest of the plant. In the future, use softer string and check ties more often as the stem thickens.

Frequently Asked Questions

Can I use the same string for multiple seasons?

No — remove and discard string at the end of each season. String that has been wet and dry repeatedly becomes brittle and can harbor disease spores. New string is cheap enough that replacing it each year is worth the disease prevention.

What if my string is too short and does not reach from the stake to the stem?

Tie two pieces of string together using a square knot, or buy longer string. Do not stretch the string tight to make it reach — it will cut into the stem as the plant grows and the stem expands.

Do I need to tie every branch or just the main stem?

Tie the main stem only. Heavy branches can be tied separately if they are drooping under the weight of fruit, but most of the time supporting the main stem is enough because the branches are attached to it.

Can I use string support on determinate (bush) tomatoes?

Yes, but it is usually not necessary. Determinate varieties are shorter and bushier, and a cage or single stake usually works fine. String support is most useful for tall indeterminate varieties that grow 6 feet or taller.