Commercial Greenhouse Foggers: A Fresh Approach to Your IPM Program

Today we’ll cover what foggers are and how you might use them for cooling, humidity, or pest control. We go over different types of foggers and how they work, discuss our experience with foggers in our greenhouses, and give you some tips on choosing the best fogger for your needs.

Foggers vs. High-Pressure Spray Equipment

A fogger is a piece of equipment that turns a certain volume of liquid into a mist or fog via a high rate of pressure. Depending on the liquid, a fogger can be used to cool the greenhouse, increase humidity, or spray pest control substances. Foggers can be stationary, portable, handheld, or aerosol canisters. 

High-pressure spray equipment (HPSE) is typically used for spot treatment of pests using a spray gun with a long hose. It is extremely taxing to treat every plant with HPSE, although it is possible. HPSE also uses more chemical and water than foggers. 

Fogger Pros

Foggers have a few excellent benefits that high-pressure spray equipment doesn’t offer. First, given the correct volume and psi setting, a fogger will fill the entire volume of your greenhouse; this means that when it’s used to treat pests or disease, it will reach every plant. 

Second, since the fogger creates a gas, fog will reach the underside of leaves, every plant, and all the cracks and crevices in your greenhouse where pests may be hiding. 

Third, foggers use less chemical and water than HPSE, making them more cost-effective.

Fourth, since foggers reach every plant by filling the volume of the greenhouse, they require much less work than HPSE. Foggers are an extremely thorough, time-efficient, and fairly cost-effective way to spray for pests.

Fogger Cons

There are a few potential downsides to using a fogger. First, fogging will cover every plant in your greenhouse, which you may want to avoid if only some plants need to be treated. Treating plants that don’t need it wastes chemical and could lead to phytotoxicity. 

Second, foggers can leave more residue on plants and the ground than other spray methods. Be aware of this as you let your crew back into the greenhouse. You may need to extend the restricted entry interval (REI) based on the condition of your greenhouse when the fogging is finished. 

Third, not all pesticides can be fogged, which simply means you must be aware of which pesticides you’re using and whether a fogger is a good fit for your greenhouse or will require a change of chemical. 

Types of Foggers

There are four main types of foggers: Thermal pulse-jet, cold, aerosol, and auto. Which fogger you choose will depend on its primary use in your greenhouse — whether for humidity or pest control. 

Thermal Pulse-Jet Foggers: These expensive handheld foggers are used in large greenhouse operations. They use heat from a pulse-jet engine to create fog and typically offer a spray that is finer, faster, and spreads further than cold foggers. However, a price tag of $1,000-$3,500 makes these perks less important.

Cold Foggers: With the most expensive cold foggers at under $500, this high volume fogger is much more cost-efficient than thermal pulse-jet foggers. It uses high pressure to create tiny droplets which are dispersed into the greenhouse from the handheld machine. It is typically used in large greenhouses. 

Aerosol Foggers: Aerosol comes as individuals canisters of pesticide, typically sold at hardware and garden stores. These are for small volume pest control in the greenhouse and are also used in homes. 

Autofoggers: Autofoggers use one or more misting nozzles and a fan to turn a small volume of pesticide into a fog. DRAMM and other companies offer small and large versions to treat a variety of greenhouse sizes.

Our Foggers

We assembled our own fogger units for two of our greenhouses based on the autofogger style. We discovered that these much cheaper homemade foggers were just as effective as expensive machinery.

For our second greenhouse, we used four Fogco fan units with 10 misting nozzles. Fogco produces this for cooling, but we modified it to spray pesticides. We attached high psi tubing to a 110 gallon tank with a pump and motor. One fan hangs in each corner of the greenhouse, with tubing attached to each fan connected to the tank outside the greenhouse. We mixed water with the desired pesticide, and the pump mixes the solution by circulating it, and then the motor pushes the solution through the tubing and into the misting nozzles. These emit fog, and the fans on each unit help it to spread and fill the greenhouse.

We employed a similar strategy in the third greenhouse — but without the Fogco fan units. Greenhouse three has eight bays, each with one line of high-pressure tubing, all of which are connected. Each line of tubing has ten misting nozzles, one every 10-15 feet across the entire greenhouse. This tubing is connected to a 200-gallon tank with a pump and motor that functions in the same way as the first version. The main difference here is that this version doesn’t have the Fogco fan units, which are expensive and not totally necessary for full coverage in this space. Fans are helpful for spreading fog through the greenhouse, but cheap box fans will do the trick with this. This version, created entirely by our team, was cheaper and still effective.

Tips for Using Foggers

Foggers are a great tool for the greenhouse and can be effective and helpful for saving time and money. Labor costs from HPSE are significantly reduced. While foggers are effective, you shouldn’t rely on them to eradicate pest infestations. Instead, use them for prevention weekly or bi-monthly, taking care to employ a holistic, integrated pest management strategy. 

If you’re able to make your own fogger, we strongly encourage you to consider that route vs. paying for an expensive product. On the other hand, an expensive machine will save you the time of assembling your own system, so choose which option works best for your business. A handheld or portable autofogger may best suit your needs if you have a small greenhouse.

Please reach out to us with questions about foggers, pest control, or controlling your greenhouse environment. We’d love to chat with you about our experience and help you grow your commercial greenhouse.

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