The Importance of Tomato Internode Length / Distance
The Internode Length Dictate Plant Height and Health. Here Is How To Control Internode Length in Tomatoes.
Table of Contents
What Is The Internode Length or Distance?
Technically it is the distance between the stem nodes. Or in simpler language the distance between the leaves on the stem.
Why Does Internode Distance Matter?
There are several reasons that I go into in the article but one of the most obvious is that the internode length dictates that plant height. Leggy plants have very long internode lengths and that means that the trusses are high off the ground. I’ve seen some so bad that the first truss is over 4 ft from ground level. Clearly we don’t want fruit sat on the soil, but too high is also undesirable.
Plus tall plants reach the top of the greenhouse or polytunnel very quickly and limit the yield.
The image on this page is of a Moneymaker tomato and shows how short the internode length can be if managed correctly. I have marked the internode length in red on the image to help make it clearer. A larger photo is repeated at the bottom the article.
At the extreme I have managed to get nine trusses on a six foot high Moneymaker plant. I’m not suggesting this is needed if growing at home, but it shows the potential.
However, to get nine trusses on short stem we must go beyond just internode spacing. The number of leaves between trusses also comes into play. The number is not fixed. It is variable. Fewer leaves means more trusses but less photosynthesis. I’ll write an article on that another day, for now let’s consider internode length.
Tomato Internode Length
How To Control Internode Length
Here are practical ways to control internode length in tomato plants for optimal growth and yield:
1. Choose the Right Variety
Bush varieties naturally have short internode lengths.
Cordon varieties (which tend to have longer internodes):
It is hard to recommend one or two varieties here as I find all of them can be grown with short internode if fed and watered correctly. To be fair, this is an art form that takes years to master. My favourites … Moneymaker and Gardeners Delight BUT they have to be good seed selection as quality has deteriorated in recent years.
2. Optimise Light Exposure
Prevent leggy seedlings:
Use strong, direct light (e.g., grow lights 2–4 inches above plants for 14–16 hrs/day).
South-facing windows or supplemental lighting is often recommended if growing indoors. BUT I have windows /light on three sides in a conservatory and find that this is insufficient compared with greenhouse.
In the garden/field:
Space plants properly (18–24+ inches apart for determinate, 24–36+ inches for indeterminate).
3. Control Temperature
Avoid excessive heat:
High temps (>85°F/29°C), especially at night, promote internode elongation. Give the plants plenty of vent at night as well as during the day when it is hot. Commercially I opened my vents in June and left them open day and night until September. Toms need good airtime circulation.
Ideal range: 70–80°F (21–26°C) day time, 60–70°F (15–21°C) night time.
4. Manage Water & Nutrients
Avoid excess nitrogen (N):
High N promotes leafy growth and longer internodes.
Use high potash fertilisers. Eg Potassium Nitrate (Tomorite) as this has reduced nitrogen and the potash improves flavour.
5. Hormonal & Growth Regulators (Advanced)
Don’t try this at home. I’m putting it here for awareness and don’t feel it is necessary, even on a commercial scale.
Gibberellin inhibitors:
Commercial products like Bonzi (paclobutrazol) or Alar (daminozide) reduce stem elongation (used cautiously in controlled environments).
Natural alternatives:
Brushing plants gently (1–2 mins/day) mimics wind stress, promoting thicker stems and shorter internodes. I achieved this by squirting water on the crop every day as a pollination aid. It works extremely well provided the weather is warm and the excess moisture can evaporate within a few hours. The evaporation raised humidity and helped pollen germination as I have explained elsewhere.
6. Avoid Overcrowding & Stress
Crowded seedlings compete for light, causing elongation (“legginess”).
Key Takeaway:
Shorter internodes = compact, sturdy plants with better light exposure and yield. Longer internodes = more vine-like growth, needing support but can produce more fruit over time.
For home growers: Focus on light, spacing, and feeding.
