Protecting the Great Lakes and other waterways is an important way to make sure that everyone has access to safe drinking water, clean beaches and a healthy environment. Understanding the Greenhouse Nutrient Feedwater (GNF) regulation helps to protect the Great Lakes by providing greenhouse operators with a cost-effective option to manage GNF in a way that reduces the amount of phosphorus entering our waterways. There are many ways the regulation protects our waterways, including:

  • requiring application setbacks from watercourses and wells
  • prohibiting application to frozen or snow-covered land
  • requiring agricultural operations to carry out sampling and analysis of soil as part of the preparation of a GNF plan
  • establishing annual, daily and hourly application rate limits
  • establishing annual, daily and hourly application rate limits
  • ensuring permanent GNF storage facilities are maintained to minimize leakage

Many greenhouse operations use circulation systems to deliver water and fertilizer to greenhouse crops that are grown without the use of soil. Some greenhouses use closed circulation systems that re-use the nutrient-rich water, or nutrient solution, continuously.

There are times when the nutrient solution is no longer suitable for growing greenhouse crops. At this point, the nutrient solution can be removed and used to fertilize other agricultural crops. GNF is the nutrient solution removed from a closed circulation system at a greenhouse operation that is registered under the Greenhouse Nutrient Feedwater Regulation, O. Reg. 300/14 (the regulation). GNF still has nutrient value suitable for certain crops. Re-using the material is a good option for some growers (Figure 1).

Flow diagram of a closed circulation system showing the movement of greenhouse nutrient feedwater
Figure 1. A closed circulation system. Greenhouse nutrient feedwater is the nutrient solution that is removed from the closed circulation system of a registered greenhouse.

The following are overviews of the regulation as it applies to:

Overview of the regulation

The regulation, made under the Nutrient Management Act, 2002 (NMA), sets out the rules for managing GNF generated by a registered greenhouse, including rules on storage, transportation and land application.

The regulation applies to greenhouse operations generating GNF and who choose to register under the regulation. It outlines how to manage the GNF generated from a registered greenhouse, including:

  • transportation of GNF between agricultural operations, including the piping of GNF
  • rules for how farmers can land apply and store GNF they receive from registered greenhouses

The regulation was developed based on an analysis of the risks posed by GNF application to land, the risk of nutrients entering waterways and the potential benefits for agricultural crops. The regulation:

  • supports the economically sustainable growth of Ontario's agri-food industry, specifically the Ontario greenhouse sector
  • provides greenhouse operators with another option to manage GNF in a way that is protective of the environment
  • provides clear, predictable rules for the greenhouse sector
  • encourages greenhouse operations to use sustainable operational practices with the option to reduce, re-use and recycle GNF
  • reduces approval costs for greenhouses and costs for farmers receiving GNF
  • provides farmers with a new source of nutrients they can use to fertilize crops

Amendments to O. Reg. 525/98 under the Ontario Water Resources Act, 1990 (OWRA) exempt greenhouse operations that register under the GNF Regulation from requiring an Environmental Compliance Approval (ECA) for sewage systems that only manage GNF (outlined in s. 53 of the OWRA). This is to ensure there is no regulatory duplication. The OWRA regulates the direct discharge of GNF to groundwater or surface water.

Part III of O. Reg. 300/14 and Part 3 of the Greenhouse Nutrient Feedwater Management Protocol set out the rules for greenhouse operations to register under the NMA. Greenhouse operations must prepare their registration in a form specified by the director and submit it to the director. The registration must contain all information required by Part III of the regulation and Part 3 of the protocol. If the operation has five or more nutrient units, a GNF strategy must also be submitted at the same time as the registration of the greenhouse operation. The strategy:

  • indicates how the nutrients will be stored
  • identifies the agricultural operation that will receive the GNF
  • must be prepared by a person who meets the requirements set out in the regulation
  • must be updated annually

The regulation adopts the Greenhouse Nutrient Feedwater Management Protocol and the Greenhouse Nutrient Feedwater Sampling and Analysis Protocol. These protocols provide additional information and requirements for managing GNF. The requirements of the protocols are part of the regulation and are legally enforceable. The protocols outline requirements such as:

  • GNF application rates
  • what greenhouse operations must provide when they register under the GNF Regulation
  • what must be included in GNF strategies, GNF plans, land application schedules and records of land application
  • sampling and analysis requirements

The Greenhouse Nutrient Feedwater Regulation gives greenhouse growers another tool to comply with environmental standards. Other than the NMA, greenhouse operations can also choose to:

  • apply the nutrient solution on land under an ECA
  • treat and discharge the nutrient solution using an approved sewage works
  • dispose of the nutrient solution at an approved waste disposal site using an approved waste hauler
  • discharge the nutrient solution to a sanitary sewer
  • discharge the nutrient solution to a septic system

These options are managed under other pieces of legislation. For more information about compliance with the GNF Regulation, the OWRA, the Environmental Protection Act, 1990 (EPA), and other options for disposing of GNF, visit the Ministry of Environment, Conservation and Parks (MECP) environmental permissions, or call the MECP Public Information Centre at 1-800-565-4923.

Ministry roles

The NMA and O. Reg. 300/14 are managed by the Ministry of Agriculture, Food and Rural Affairs (OMAFRA) and enforced by the MECP. Environmental protection is a top priority for both ministries.

OMAFRA is responsible for approvals, training, education and outreach under the NMA, accepts registration and strategy submissions and approves GNF plans.

MECP works with the greenhouse sector to improve environmental performance. They carry out proactive inspections of greenhouses to ensure compliance with the regulation and protection of the environment and they are responsible for enforcing compliance with the OWRA, the EPA and the NMA.

Training and education

The regulation prescribes a number of nutrient management practices. These practices include:

  • preparing GNF strategies, plans or land application schedules for an agricultural operation
  • engaging in the business of applying GNF to land at an agricultural operation subject to a GNF Plan
  • transporting GNF
  • land applying GNF at an agricultural operation

Before carrying out any of these practices, you must meet the requirements and complete the appropriate training. There are different requirements depending on the practice you wish to do.

GNF training requirements

Training requirements are found in subsections 71(5) and 71(6) of the regulation.

For nutrient management consultants and people wanting to prepare GNF strategies, plans and land application schedules for agricultural operations they do not own, operate or work for:

For GNF generators and receivers, greenhouse controllers and farmers wanting to prepare GNF strategies, plans and land application schedules for operations they own, manage or work for:

  • no specific certification is required
  • you must complete online training for greenhouse operators to allow them to review the regulatory requirements and to submit documents to OMAFRA

For independent carriers and people wanting to transport GNF for and between operations they do not own, operate or work for:

For people who represent businesses that want to land apply GNF and/or complete Land Application Schedules for agricultural operations they do not own, operate or work for, and the operations are subject to a GNF Plan:

For operators of land application equipment wanting to land apply GNF for agricultural operations they do not own, operate or work for:

GNF training and educational materials for individuals or companies who are interested in carrying out the practices listed are available from the University of Guelph Ridgetown Campus. More information on nutrient management courses and certification opportunities is also available.


For more information on the Greenhouse Nutrient Feedwater Regulation or registering your operation under the NMA, contact the Agricultural Information Centre at 1-877-424-1300 or


The information provided is for informational purposes only. This fact sheet provides a general and simplified description of some of the legal requirements of O. Reg. 300/14 (the "Regulation"), the Greenhouse Nutrient Feedwater (GNF) Management Protocol and the GNF Sampling and Analysis Protocol. The protocols are adopted by the regulation and are legally enforceable. This information does not provide a comprehensive description of the rules that are mentioned and there are rules in the regulation and protocols that are not covered at all. To determine your legal obligations, consult the relevant law. If legal advice is required, consult a lawyer. In the event of a conflict between the information in this fact sheet and any applicable law, the law prevails.