I love living inside a greenhouse but it does require maintenance such as cleaning the roof. My greenhouse has twin-walled polycarbonate panels instead of glass. It is 60’ long by 36’ wide by 12’ high at the gutters and approximately 24’ high at the roof ridge. There are clear panels on the north-facing roof and translucent light-diffusing panels on the south-facing roof.

Ideally a greenhouse is not surrounded by tall trees that cast shade and debris onto the greenhouse’s roof. But here the trees serve several beneficial purposes such as shade from part of the hot afternoon sun, wind-break during fall and winter storms, and privacy from the road and neighbors’ view. I removed only trees within the greenhouse footprint, dead trees, or any leaning toward structures which left dozens of trees encircling my property.

However, the roof didn’t actually need washing the first couple years. Between the slope and frequent rain, most debris washed down to the gutters. Until the worst tree pollen season anyone ever remembers. Everything from cars, to buildings, to gardens, to paved surfaces was coated with sticky orange pollen that soon decayed to a sickly blackish grey. With summer sunlight streaming through the greenhouse walls, it became painfully obvious that my greenhouse roof had accumulated a thick layer of tree pollen.

Although I’ve been able to clean the gutters from a 14′ telescoping ladder, I’ve previously tried to wash the roof from the ladder but couldn’t reach to the peak. While mine is a modest structure for a commercial agricultural greenhouse, its roof is just high enough to pose a challenge. Tying the pressure washer to the top of a ladder and working from another ladder was high risk to damage the panels and was awkward to reach the peak.

Next idea was to use plywood to make a level surface at roof height for the pressure washer and then climb the roof to reach the peak. However, the wet pollen layer was too slippery for both the worker and the pressure washer and this was quickly abandoned.

Final idea was to wet the roof from the garden hose and then scrub with a soft brush on an extension pole. This allowed the worker to reach the peak while climbing to only the first rung.

Ultimately, including 2 trial and error attempts, it took less than a full day to complete the entire roof. Pollen events like the one that caused the need to wash the roof this time are less than once in ten year events. I do not expect to need to wash the roof every year; possibly not even every 2 to 3 years. And now that I know what works and doesn’t work, the next time should take about four hours.