Keep Your Greenhouse Squeaky Clean

Weeds can attract and harbor pests and diseases in the greenhouse.

From Botrytis to Thielaviopsis, diseases on greenhouse plants threaten to wipe out your most valued investment. This could equate to tossing a few impatiens or, worse, throwing out an entire crop. There’s a reason for the saying cleanliness is next to godliness — you need to be religious about greenhouse sanitation.

Getting Started

“Starting clean and staying clean is important,” says Paul Pilon, horticultural consultant and owner of Perennial Solutions Consulting. “Most greenhouse growers are good at sanitation when bringing plants in, but can’t keep it up throughout multiple production cycles.”

The best way to ensure everything starts clean is to tackle an empty greenhouse. Everything from pots and containers to benches and equipment needs to be sanitized with products containing active ingredients like quaternary ammonium, hydrogen dioxide or chlorine dioxide. This process should be repeated between crop cycles.

“Start from ground zero and go from there,” Pilon says. “Any time there is an opportunity to clean benches, we need to take advantage of those windows of opportunities.”

Top Sanitation Must-Dos

Clean up a dirty greenhouse using these ten steps.

1. Wash Your Hands before working with plants. Sinks and hand sanitizer stations throughout the greenhouse make washing up convenient.

2. Use Disinfection Mats Place these mats at all greenhouse entrances, and ask workers to step on them with both feet before going inside.

3. Clean Materials Often This includes tools, flats, benches and other greenhouse equipment. Disinfect with products, wash or steam between cycles.

4. Check For Problems Upon Arrival New plants should be inspected for diseases and pests before entering the greenhouse setting. Reject shipments problematic shipments right away.

5. Remove Problem Plants Carefully using lidded trash cans or plastic bags. These plants should be discarded outside the greenhouse.

6. Keep Clean Items Off The Floor This is a perfect spot for contamination; anything that lands on the floor should be sanitized before being reused. Use different cleaning materials on the benches and the floor to avoid cross-contamination.

7. Dispose Of Weeds And Debris such as used soil, old tags and dead leaves. In the work space, these items attract pests and diseases that can contaminate new materials. Sweep and wash the floors regularly.

8. Keep Trash Outside Trash bins can harbor unwanted pathogens and pests. If they cannot be kept outside, seal them with a lid and empty the contents daily.

9. Dress The Part by avoiding yellow and blue clothing. These colors attract insects. Remove dirt from shoes before stepping inside. Consider using gloves when planting and propagating.

10. Train Staff In The Art Of Clean Each worker should be able to identify pest and disease problems, as well as follow sanitation procedures to avoid contaminating healthy plants.

Once the greenhouse interior is cleaned and ready for plants, be sure to inspect for problems such as leaf spotting or pests. Some sanitation guidelines suggest checking every 100 plants or every five to 10 feet on
the benches.

Be sure to pay special attention to crops that require a high level of sanitation such as geraniums. Pilon also mentions that some articles suggest quarantining the problem crops, but such extreme measures may not be necessary.

“It’s not cut and dry. Different crops need more sanitation,” Pilon says. “Many growers have observed a problem on the incoming line but did not deal with it right away. Be proactive instead of reactive.”

Key Points

The propagation areas and sections where there are a lot of plants require some of the highest levels of cleanliness, Pilon says. Plants and dirty equipment should be kept off the greenhouse floor or other contaminated surfaces.

For the most part, growers should not reuse flats. If you are reusing flats, be sure to wash and disinfect them between cycles. Soil, however, should never be reused.

“Reused soil is a big area of contamination.” Pilon says.

To ensure contaminated soil does not infect new soil, the greenhouse should be swept and the areas underneath benches, containers and equipment should be cleaned and sanitized. Hoses and water left on the floor also act as breeding grounds for bacteria, so hose hooks should be installed and water cleaned up.

To ensure success with your sanitation program, the best approach is to remain vigilant about cleaning procedures.

“I think we miss a lot of what’s on the materials we bring into the greenhouse,” Pilon says. “Know what you have and head off any problems before they magnify in the greenhouse setting.”

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