[rozalia]

We have large polytunnel (20ftx 12) and its been up for 2+ years.  The outside surface was getting very green (unfortunately its near trees) so I cleaned what i could reach last autumn. I used a step ladder and bought a long handled sponge kitchen mop. Managed to wash about 75% but can't reach the top ridge. 
The area around the polytunnel is not very level so balancing on a longer step ladder is not an option.  We don't have a tap for a pressure washer (our water is from the nearby pond). Can anyone suggest how I can clean off the green algae/mould from the top.  Many thanks!

[joyfull]

the only thing I can think of is to hire a cherry picker from your local hire company - a wheeled version should be able to cope with the uneven ground either that or you may need to put down some scaffolding boards to level it off.

[RichardA]

caravan and haulage business suppliers (perhasp boat yards) sell telescopic handled soft brushes but at the end of the day if the job cannot be done safely then one option is just not to do it at all. A good clean on most of the tunnel will do wonders for the light incoming so the ridge is less important especially if near trees.
Some jobs just cant be done at reasonable cost sometimes
R

[mumofstig]

could you throw an old blanket over (lengthen the sides with string so it reaches) and with one person each side just pull it backwards and forwards along the tunnel 

[rozalia]

Thanks- like the long handled Caravan brush idea and think the blanket idea might work. I'll let you know what works.

[RichardA]

top of my polytunnel has about a metre width of debris net on it as otherwise birds sit up there and peck through at the crawling insects they can see under their feet inside the ridge of the polytunnel so I am not over bothered about cleaning the ridge in my case.
R

[Henwoman]

Mine's just been cleaned, with a soft sweeping broom but like you, we couldn't reach the ridge so have left it green.  I like the idea of the blanket though - good lateral thinking!