24. Crop density: how to calculate it to maximize yield and quality

Growing density is one of the most important-and often most underestimated-parameters in vertical farming and indoor cultivation. Deciding how many plants to fit in a given space completely changes yield, consumption, final quality and operational management.

Too low a density means wasted space.
Too high a density means stressed plants, slow growth and risk of mold or disease.

In this article we look at how to calculate optimal density, what variables to consider, and how modern technologies (such as Tomato+ greenhouses) allow it to be optimized automatically.

What is crop density

Growing density indicates how many plants are present per unit area (plants/m²) or per individual growing module.

In a multilayer system, you work on two levels:

1. density per tray or stand,

2. density per total square meter, taking into account the number of vertical levels.

Why density is crucial

Density directly affects:

• Photosynthesis → more plants = more mutual shading.

• Airflow → stagnant air = mold risk.

• Water and nutrient consumption → higher density = higher demand and faster changes in EC/pH.

• Light management → LEDs must provide sufficient PPFD even in lower layers.

• Yield per cycle and per year → wrong density = loss of annual productivity up to 40%.

Efficient cultivation does not aim for the maximum number of plants put in, but the maximum number of plants that grow well.

How to calculate optimal density

1. Start with the size of the adult plant.

Each species has a necessary "living space":

• Microgreens → high density (up to 1200-2000 plants/m²)

• Basil → medium density (200-300 plants/m²)

• Lettuce → lower density (20-35 plants/m²)

Consider final canopy diameter, not just initial stage.

2. Consider plant height and stratification.

In a vertical farm system count:

• height between levels,

• shading risk,

• uniformity of PPFD.

The more the plant grows in height, the fewer layers can be used.

3. Adjust density to available light

Insufficient light = spindly plant or slow growth.

Practical examples:

• With high PPFD (200-300 µmol/m²/s) → highest possible density.

• With lower PPFD (80-120 µmol/m²/s) → reduced density to avoid competitive stress.

Density is optimized only if light reaches each plant evenly.

4. Consider the microclimate

Higher density = higher local humidity = higher risk.

Need an airflow system designed to:

• avoid pockets of moisture,

• remove heat,

• maintain stable VPD.

5. Calculate real (not theoretical) density.

Simple formula:

Density = Total number of plants / Useful cultivable area

Example:

• 0.25 m² tray

• 50 plants

→ Density: 200 plants/m².

Repeat for each level and sum to get the overall density of the multilayer structure.

Dynamic density: the new standard in vertical farming

In the most advanced technologies, such as Tomato+ greenhouses, density is no longer a fixed parameter but a variable managed by software and data.

Thanks to:

• height sensors,

• AI chambers to recognize plant status,

• 6-channel dynamic light control,

• feedback loop Cloud → AI → greenhouse,

the system can automatically adapt crop parameters according to the density present.

Real examples:

• If density is high → greenhouse increases targeted illumination in shaded areas.

• If plants compete for space → the Growth Plan is modified in real time to avoid stress.

• If the canopy expands more than expected → the AI corrects light and irrigation.

This allows high yields even under less than perfectly optimal density conditions.

How to choose the right density in practice

For microgreens

• Very high

• Significant mat thickness

• Recommended PPFD: 80-180 µmol/m²/s
  Ideal density: 1200-2000 plants/m²

For aromatics (basil, cilantro)

• Medium

• Attention to light competition
  Ideal density: 200-350 plants/m²

For baby leaf

• Medium-high
  Ideal density: 400-700 plants/m²

For lettuce or broadleaf

• Low
  Ideal density: 20-35 plants/m²

Conclusion

Calculating the optimal density means finding the balance point between yield and quality, not simply putting in as many plants as possible.

In modern vertical farming, density is no longer a limitation but a dynamic parameter that can be optimized using data, sensors, and artificial intelligence built into Tomato+ greenhouses.

The combination of technology, AI and a scientific approach allows for maximum productivity, minimal competition and consistent quality 365 days a year.

Thank you for reading this article. Keep following us to discover new content on hydroponics, vertical farming, and smart agriculture.
Tomato+ Team