Regular checkups

As a greenhouse grower, you know maintaining and protecting your greenhouse is as important to your bottom line as a good yield. In fact, the two go hand in hand. Proactively maintaining your greenhouse can help reduce equipment failures, increase operating efficiencies and improve product yields.

But greenhouse maintenance is more than just kicking the tires of your operation every once in a while. Your maintenance plan should include routine inspections of your frames, glazing, ventilation, heating and more. If you don’t already have a regular maintenance schedule, create one. It’s also helpful to keep a repair log and note any potential maintenance issues. Assign the task to an employee who is familiar with your greenhouse and can manage pre-season or multi-annual inspections. The effort could extend the life of your expensive machinery and likely strengthen your business’ bottom line.

Here’s my recommended checklist to get you started.

Paneling and glazing

A variety of greenhouse coverings exist, so be sure your maintenance plan suits your materials. Also, different glazing types — including glass, poly film and polycarbonate —require different maintenance plans. Adjust accordingly.

Do a visual inspection: Look for areas where you need to repair tearing or broken or slipped glass. Make note of any cracked or missing sheets of polycarbonate. Check for loose screws and attachment extrusions.

Check the clips: Ensure all the clips hold the glazing panels in place. You can secure loose glazing clips in place with silicone sealant to provide extra strength against strong winds.

Check bar caps: Regularly test your bar caps for tightness if you’re using glass panes.

Wash panels: Wash polycarbonate and acrylic panels with a mild detergent and lukewarm water using a soft sponge to remove dirt, smog and debris. Once clean, test and measure the level of lighting.

Address spray-on shading: If you apply shading in the summer, wash it off in the fall. You can remove spray-on shading with a cleaning compound or a commercial shade remover. Spray on the cleaner, let it stand for a few minutes, then thoroughly flush with clean water.

Examine your poly cover: Repair small holes or tears with polyethylene tape. If your poly has stretched or loosened, you can tighten it by removing the lock strip inserts and pulling the plastic taut. Plan to replace plastic that’s older than four years. Don’t forget to clean and inspect the inflation blower. Set inflation pressure so it’s about the same as an inflated balloon.

Minimize heat escape: For an older glass greenhouse with broken or slipped glass, cover it with a layer of film poly to reduce heat loss. For loose poly covering, an air-inflated poly tube located halfway between the ridge and eave will keep the plastic rigid and help shed snow.

Frames

Different frame materials require slightly different checklists. However, daily wear and tear — and severe weather like hail, snow or wind — can weaken any greenhouse frame. Include the following tasks in your maintenance worksheet.

Paint or scrub: For wood frames, save painting or staining for summer. For aluminum frames, address any signs of corrosion or wear and tear.

Examine low areas and corners: Don’t forget to look down. Clean any rust or corrosion from bolts and framing materials at ground level. Also check for mold or rot on wood frames.

Replace damaged frame components: If you’ve discovered damage to any part of your structure’s framing or bracing, replace the bent or damaged materials. Even a slight dent or bend can dramatically reduce the strength of some structural components, leading to a higher risk of collapse when tested by wind or weight. Tighten collar tie and truss bolts. Excessive heat and constant wind can loosen these crucial frame mechanisms.

Ventilation and fans

Greenhouse vents play a critical role in creating a safe environment for your plants by replenishing CO2 and removing excess heat and moisture. Exhaust fans work in partnership with your shutters and vents. These tips can help keep your greenhouse grow-ready.

Lubricate vent components: Roof and sidewall vents get a lot of use, so they need continuous attention. Lubricate bearings, racks and pinions, and vent arm hinge points. Also grease the shutter hinge points so they close tight. Don’t forget to check the fluid in your gearbox drives.

Fix loose-closing vents: If your vents don’t close tight, you can add weather stripping to help stop excess permeation.

Check vent position switches: With automated vents, double-check the minimum and maximum vent positions to ensure they stop at the correct spot.

Check hinges and catches: With manual vents, windows or louvers, test to make sure the hinges and catches work smoothly. Grease the linkages if they don’t.

Inspect fan components: Always disconnect power when inspecting your fans. Check for loose or worn belts, clean fan blades and tighten or replace any screws that vibrated loose.

Clean horizontal air flow (HAF) fans: If the fans are hardwired, be sure to follow proper lockout/tagout procedures. Clean the blades and guards. Oil the bearings if they aren’t sealed. Clean evaporative cooling pads. Regularly clean and disinfect your cooling pads to enhance airflow and minimize fungus growth.

Heaters and boilers

A functioning and efficient boiler is a crucial part of your greenhouse — and not something you want breaking down in the middle of a cold snap. Your maintenance goal here is to keep your heater running smoothly at all times.

Service all equipment before the heating season begins: It’s important to have your heating unit inspected annually by a licensed heating, ventilation and air conditioning (HVAC) company to ensure your heaters and exhaust pipes are clean and in safe operating condition.

Check limit controls: Evaluate for efficiency status:

• * High heat
• * Fan or blower operation
• * Barometric draft control on the flue pipe
• * Safety pressure relief valves on boilers

Remove dangerous debris: Blow out burner ports and clean heater of any spider webs, bird/wasp nests or any other debris.

Inspect heat exchangers: Check for leaks and corrosion and clean heat-exchanger surfaces. Vacuum and use a wire brush to clean radiators and fan pipes.

Check for combustion potential: Look for signs of fuel or gas leaks and reestablish proper clearances of any flammable liquids or combustible materials near heating equipment.

Do a combustion test: Check efficiency, draft and smoke level with a combustion test on the heating unit.

Do a test run: Test your heating systems to ensure they heat your greenhouse as expected. Also test run the back-up generator and check its fuel supply.

Floors and doors

Floors need to allow for good drainage and insulate the greenhouse from cold. Doors need to seal properly for optimal insulation and pest control.

Regularly clean the floor: Use soap and a disinfectant to scrub concrete floors. Remove any dirt, debris and algae, and pay close attention to corners, cracks and areas under benches.

Repair floor cracks: Remove any weeds or debris from cracks and crevices. Repair cracks in concrete with caulk or other repair material. You can repair a cracked concrete foundation wall with an epoxy adhesive.

Consider floor insulation: To avoid heat loss, insulate as deep as the frost line around the perimeter of a heated concrete slab floor. Some growers have even insulated below the slab.

Inspect doors: Add or replace weatherstripping to reduce permeation through small gaps around doors. Use brush-type astragal weatherstripping on sliding doors. Replace worn doors showing large gaps with insulated steel doors and frames.

Pests and disease

Keeping pests and disease at bay in your greenhouse is a vital part of greenhouse maintenance. Common pests in warm, humid conditions include aphids, red spider mites and mealy bugs. Common diseases and conditions include mildew and botrytis. To help keep your yields safe, follow these tips.

Disinfect irrigation and holding tanks: Irrigation lines and holding tanks develop algae and can host thousands of gnats, which are a threat to small roots.

Prevent invasion: Thoroughly inspect your greenhouse for small gaps in the base, frame or glazing panels and properly fill them. Make sure your doors close tightly.

Deep clean: Schedule time to deep clean your greenhouse to help alleviate disease propagation, mold and pests that might otherwise overwinter.

Zach Bruce is the safety services manager for Hortica, a brand of the Sentry Insurance Group. hortica.com

Read the rest of Greenhouse Insider:

Sponsor Letter: A welcome message from the NGMA president

Case Study: A lasting legacy

Upgrades: Prioritizing upgrades

Construction: Zoning approval procedures

Membership: 2024 NGMA member list