Boost tomato harvest with single-stem trellising

What you do

This method, called single-stemming and string trellising, aims to avoid tangled vines, yellowing leaves, pest problems, and low yields often associated with traditional tomato growing. This method has been used for ten years, harvesting large, juicy tomatoes from a 9x4 raised bed.

First, an overhead support structure is needed. This can be a trellis bar, greenhouse rafters, house eaves (if south-facing), or a custom-built wooden frame. You can use 4x4 posts vertically with 2x4s across and 2x3s horizontally, attaching screw eyes to the underside of the horizontal beams. Smaller wood like 2x4s for uprights and 1x2 furring strips for cross-braces can also be used, but may degrade faster.

Twine is tied securely to the overhead support. The bottom of the twine is anchored by burying it under the root ball of the newly planted tomato or by tying it to a stake in the ground. The twine should be perfectly vertical.

The core of the method is single-stemming: growing the tomato plant with only one main leader. This involves regularly removing "suckers"—small shoots that grow in the junction (armpit) between a leaf and the main stem. As the plant grows, its main stem is gently twisted around the vertical twine for support. Tomato clips can also be used but are not strictly necessary. This twisting should ideally be done later in the day when the plant is warmer and more flexible to prevent snapping the stem. If the main tip snaps, the next available sucker is trained to become the new main leader.

For gardeners in zones 6 through 11 (or similar long-season climates), a tweak can increase harvest by 30-40%. Instead of cutting off the plant's top when it reaches the end of the string, a tomato hook is used. The hook allows you to unhook the twine, release a few wraps, and lower the entire plant. This gives the vine more vertical growing space, extending its productive life.

Why it works

This method concentrates the plant's energy into growth and fruit production, rather than dissipating it into numerous unproductive branches and leaves. By removing suckers, the plant develops "apical dominance," directing hormones and resources to the main stem and its fruit. This results in more, larger tomatoes.

Single-stemming also significantly improves air circulation around the plant, which is crucial for preventing diseases like mildew, especially in humid climates. With a less dense canopy, it's much easier to spot and address pest problems (like hornworms or aphids) early, before they cause significant damage. Harvesting is also simplified as the fruit is openly visible and accessible, rather than hidden within a dense bush. Additionally, this vertical growing technique is a major space-saver, allowing for more plants (and thus more variety) in a smaller garden footprint.

Try it

1. Install Overhead Support: Set up a sturdy overhead structure (e.g., a simple wooden frame, a pergola, or use house eaves if south-facing) that can support the weight of mature, fruit-laden vines. Ensure it is at least 6-8 feet high. For hot/tropical climates, consider materials that withstand humidity and sun exposure.
2. Attach Twine: Securely tie a strong, UV-protected twine to the overhead support for each tomato plant you intend to grow.
3. Plant Tomatoes: Plant indeterminate tomato seedlings directly beneath each twine. Anchor the bottom of the twine by burying it under the root ball or tying it to a ground stake.
4. Single-Stem: Regularly inspect your tomato plants (every 1-2 weeks) for "suckers"—small shoots emerging from the junction between a leaf and the main stem. Pinch or snap these suckers off to maintain a single main stem.
5. Twist/Clip to Twine: Gently twist the main stem of the tomato plant around the vertical twine as it grows. Alternatively, use tomato clips to secure the stem to the twine. Perform this in the late afternoon when stems are more flexible to avoid breakage.
6. Extend Season (Long-Season Climates): If you have a long growing season (like many hot/tropical regions), once the plant reaches the top of your support, use a tomato hook. Unhook the twine, release a few wraps, and lower the plant, allowing it to continue growing and producing fruit.

Watch out for

• Snapping Stems: Be gentle when twisting or clipping the plant to the twine. Stems are more brittle in the morning; try to do this task later in the day when they are more flexible.
• Consistent Maintenance: Single-stemming requires regular removal of suckers. Neglecting this will result in a bushy plant, negating the benefits of the method.
• Sturdy Support: Ensure your overhead structure is robust enough to bear the significant weight of mature, fruit-laden tomato plants. Weak structures can collapse.
• Indeterminate Varieties: This method is primarily for indeterminate tomato varieties, which continue to grow and produce fruit throughout the season. Determinate varieties have a more compact growth habit and may not benefit as much.