How Ozonated Irrigation Water Improved Root Development and Reduced Greenhouse Crop Losses by Millions

Water quality is one of the most important — and often overlooked — factors in commercial greenhouse production. Contaminated irrigation water can introduce pathogens, algae, and biofilm that weaken plant roots, slow growth, and increase crop losses.

A large-scale irrigation water study conducted at Metrolina Greenhouses evaluated the impact of ozonated irrigation water on plant growth, crop production speed, and greenhouse operational efficiency.

The results were significant: faster root development, shorter crop cycles, reduced fungicide use, and a dramatic reduction in crop shrink — saving millions of dollars annually.

The Challenge: Irrigation Water Quality in Large Greenhouse Operations

As one of the largest greenhouse operations in the United States, Metrolina Greenhouses produces millions of plants each year for major retailers across North America.

Like many large greenhouse facilities, the operation relies heavily on pond and well water for irrigation.

While cost-effective, untreated irrigation water can introduce several challenges:

• Algae growth in irrigation systems

• Biofilm buildup in pipes and filters

• Pathogens in irrigation water

• Slower root development in young plants

• Increased disease pressure

Over time, these issues can impact plant quality and increase production costs.

Prior to improvements in irrigation water treatment, the facility experienced significant annual crop shrink, with dump losses ranging from $1.7 million to $5.4 million per year.

The Solution: Ozone Water Treatment for Irrigation

To improve irrigation water quality, the greenhouse implemented an ozone water treatment system to treat pond water before it entered the irrigation system.

Ozone is a powerful oxidizer that helps improve irrigation water by:

• Destroying pathogens and microorganisms

• Breaking down organic contaminants

• Preventing algae growth

• Removing biofilm buildup in irrigation systems

• Delivering cleaner water directly to plant roots

Unlike many chemical treatments, ozone naturally breaks down into oxygen and leaves no chemical residue.

Trial Results: Pansy Root Development After 14 Days

A controlled greenhouse trial compared pansy plug development using three different irrigation water sources:

• Ozonated pond water

• Raw pond water

• Raw well water

After 14 days of growth, pansy plugs irrigated with ozonated pond water showed significantly stronger root development than plants receiving untreated water.

Growers observed several improvements:

• Faster root expansion

• Greater root density

• Improved early-stage plant vigor

• More uniform growth across trays

Strong early root development is critical because it allows plants to establish faster and move through production more efficiently.

Cool Wave® Pansy Variety Performance

The trial also evaluated plant performance using the Cool Wave® pansy variety, a widely grown spreading pansy used in commercial bedding plant production.

When comparing plants irrigated with ozonated pond water versus untreated pond water, the Cool Wave pansies receiving ozonated irrigation showed stronger growth and better uniformity.

Key observations included:

• Larger plants early in development

• More consistent growth across trays

• Faster establishment after transplanting

These improvements are particularly important for greenhouse growers producing high-volume branded varieties, where uniformity and production timing are critical.

Production Improvements After Full System Installation

Following the successful trial results, a full ozone water treatment system was installed at Metrolina Greenhouses.

The greenhouse reported several measurable improvements across its production operations.

Faster Crop Production

Growers reported significantly shorter production times across multiple bedding plant varieties.

Production improvements included:

• 7–10 days faster production on most liners

• Up to 2 weeks faster growth for begonias, petunias, and marigolds

• 3 weeks faster pansy development in 88-cell trays

• 1 week faster pansy development in 288-cell trays

Overall, total cropping cycles were reduced by 2–4 weeks.

For large greenhouse operations producing millions of plants annually, even small improvements in production speed can significantly increase total output capacity.

Reduced Fungicide Use

Improved irrigation water quality also reduced disease pressure in the greenhouse.

After installing the ozone system, the operation reported:

20% reduction in fungicide use

Lower chemical use not only reduces production costs but also improves sustainability and worker safety.

Stronger Plants and Better Shipping Performance

Plants grown with ozonated irrigation water developed stronger and more robust root systems.

These stronger plants resulted in:

• Reduced plant damage during shipping

• Improved shelf life at retail locations

• Greater tolerance to short-term drought stress

• Higher overall plant quality

For greenhouse operations supplying major retailers, stronger plants help reduce returns and rejected shipments.

Cleaner Irrigation Infrastructure

Continuous ozone treatment also improved the greenhouse’s irrigation system performance.

The treatment system helped eliminate:

• Biofilm buildup inside irrigation pipes

• Algae accumulation in filters and emitters

• Organic contamination in irrigation lines

Cleaner irrigation systems lead to:

• More uniform watering

• Reduced maintenance requirements

• Longer irrigation equipment lifespan

Financial Impact: Millions Saved in Crop Losses

One of the most significant benefits of improved irrigation water treatment was the reduction in annual crop shrink (dump losses).

Prior to implementing the ozone system, dump losses ranged from $1.7 million to $5.4 million annually.

Annual Dump Losses

Fiscal Year	Dump Loss	Percent of Sales
2008	$5,430,933	4.31%
2009	$4,281,259	3.29%
2010	$2,881,092	2.31%
2011	$1,789,432	1.38%
2012	$2,037,239	1.45%
2013	$2,817,851	1.93%
2014	$827,153	0.53%

By 2014, after implementing ozone water treatment, dump losses had dropped dramatically to $827,153, representing only 0.53% of total sales.

This improvement represents millions of dollars in recovered revenue annually.

Key Benefits of Ozonated Irrigation Water for Greenhouse Production

Plant Health Benefits

• Faster root development

• Stronger root systems

• Improved plant uniformity

• Faster crop cycles

Operational Benefits

• Reduced fungicide use

• Cleaner irrigation systems

• Less algae and biofilm buildup

• Reduced maintenance requirements

Financial Benefits

• Significant reduction in crop shrink

• Faster production cycles increase capacity

• Millions saved in annual losses

Why Irrigation Water Treatment Matters for Greenhouse Growers

Water quality plays a critical role in greenhouse production efficiency and plant health.

The results observed at Metrolina Greenhouses demonstrate how improving irrigation water quality can dramatically improve both plant performance and operational profitability.

For growers producing millions of plants annually, even small improvements in plant health and production speed can translate into major financial gains.

Learn More About Greenhouse Water Treatment Solutions

Advanced Treatment Technologies provides water treatment systems designed for greenhouse and agricultural irrigation applications.

Our solutions help growers:

• Improve plant health

• Reduce chemical inputs

• Eliminate algae and biofilm

• Increase production efficiency

To learn more about how ozone water treatment can improve your greenhouse operation, visit:

AdvancedTreatmentTechnologies.com Greenhouse Irrigation Water Treatment FAQ Frequently Asked Questions About Greenhouse Irrigation Water Treatment

What is ozone water treatment in greenhouses?

Ozone water treatment uses dissolved ozone gas to disinfect irrigation water before it reaches plants. Ozone destroys bacteria, algae, and plant pathogens while also breaking down organic contaminants. Because ozone naturally decomposes into oxygen, it leaves no chemical residue in greenhouse irrigation systems.

Why is irrigation water quality important for greenhouse  crops?

Irrigation water quality directly affects plant health, root development, and disease pressure. Poor water quality can introduce pathogens, algae, and organic contaminants into irrigation systems. Maintaining clean irrigation water helps prevent root diseases, improves nutrient uptake, and supports consistent plant growth.

How does ozone improve irrigation water quality?

Ozone is a powerful oxidant that quickly destroys microorganisms in irrigation water. It can eliminate bacteria, fungi, algae, and biofilm that accumulate in irrigation systems. By reducing microbial contamination, ozonated water helps maintain cleaner irrigation lines and healthier root zones.

Can irrigation water affect root development in greenhouse plants?

Yes. Irrigation water quality can significantly influence root health and development. Water containing pathogens or high organic loads can stress plant roots and reduce growth. Clean, well-treated irrigation water supports stronger root systems and improved nutrient absorption.

What are common contaminants in greenhouse irrigation water?

Common irrigation water contaminants include algae, bacteria, fungi, biofilm, and organic matter. Surface water sources such as ponds and reservoirs may also contain plant pathogens that can spread disease through irrigation systems if not properly treated.

What are the benefits of ozone irrigation water treatment?

Benefits of ozone treatment for greenhouse irrigation water include:

• destruction of plant pathogens

• improved root zone health

• reduced biofilm buildup in irrigation lines

• improved water clarity

• no chemical residue in irrigation water

Why do large commercial greenhouses treat irrigation  water?

Large commercial operations such as Metrolina Greenhouses treat irrigation water to maintain consistent crop quality and prevent disease outbreaks. Water treatment helps protect plants from pathogens, maintain clean irrigation systems, and improve overall production reliability.