Summer is the perfect time for spring cleaning

Sep 09, 2023

For many ornamental greenhouse crop producers, summer finally provides the time to do some much-needed spring cleaning around the greenhouse. Once bedding plant season has ended and garden mums have been planted, but before poinsettias have taken over, is an excellent time to get into the greenhouse and clean, clean, clean!

A clean greenhouse really is one of the most important things to aspire for, as the payoffs can be numerous — less pests and diseases, weed-free containers, safer working spaces for employees, and a workspace that is enjoyable and makes you proud.

The first step in cleaning the greenhouse is to get rid of weeds, debris, growing substrate and plant material. For those plants that are still living and in the greenhouse, why are they there? Carrying over living plant material from season-to-season is one of the easiest ways to harbor pests and disease, making it impossible to break the cycles of infestation and infection. While “pet plants” are certainly enjoyable, they are not well-suited for commercial production facilities. Holding on to leftover crops? Pitch them! They take up space, cost money to maintain, and likely will not be sold. Coarse brooms, floor sweepers can be used once large materials have been picked up off the floor. However, before floors get swept, clean up any spaces above the floor first. Cleaning in a top-to-bottom direction will help remove the most dirt and dust from the greenhouse.

While we generally think of non-living debris when considering cleaning, let’s not forget about those problems that may be alive like algae and weeds. The combination of water, light, and nutrients provide the ideal place for algae to grow and thrive inside the greenhouse. However, it can make surfaces slippery and unsafe, and reduce the effectiveness of equipment, too. Algaecides including hydrogen dioxide and peroxyacetic acid product (ZeroTol 2.0 or OxiDate 2.0), quaternary ammonium product (Green-Shield, KleenGrow, and Physan 20), or sodium carbonate peroxyhydrate (GreenClean Pro Granular Algaecide) to kill any remaining algae. Hand-pulling weeds inside the greenhouse is going to be the best way to kill weeds when plants are in the greenhouse, but several are labeled for use inside if no plants are present.

Once the greenhouse space has received a general cleaning to get rid of debris, dirt and dust, it is time to move from cleaning into sanitation. Before you think about saving time and going straight to sanitation, stop right there. Unless surfaces are cleaned first, steps to sanitize the greenhouse will be rendered much less or completely ineffective. With surfaces cleaned, what are you going to use to sanitize the greenhouse? Well, that depends on what it is you are trying to sanitize: Containers, tools, floors, benches, cooling pads, irrigation systems? As previously mentioned, hydrogen dioxide and peroxyacetic, quaternary ammonium and sodium carbonate peroxyhydrate are all effective sanitizers, but have their own advantages and disadvantages. The ability to use these compounds in greenhouses with or without plants, the duration of contact time, etc. vary among the different products. You will need to evaluate the task at hand and pick the right tool for the job.

Keeping a clean greenhouse is not necessarily the most exciting or enjoyable part of the job. While correlation does not imply causation, it is no coincidence that many of the most successful growers maintain clean production facilities. While this article is focusing on taking advantage of the summer lull, these practices can and should take place to some degree throughout the year. Make the time to give your greenhouse the cleaning and sanitizing your crops deserve.

Christopher is an associate professor of horticulture in the Department of Horticulture at Iowa State University. [email protected]

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