The polytunnel has developed a layer of green algae on the outside along with a bit of urban pollution (we are under the Heathrow flightpath and not far from a busy A road) along the roof – so time for a good clean.


Last year I had scrubbed out the interior, surprised at the amount of green growth on the inside of the tunnel.  Surprised because that hadn’t been my experience with the previous tunnel at Park Road – different plastic perhaps, albeit from the same supplier.

I’d done a bit of internet research for the best way to clean the outside of a polytunnel and the best products to use.  It seems the best way to clean a tunnel is with two people, an old sheet and two lengths of rope; however, there was only me (the under-gardener is a fair-weather allotmenteer) and a recent spot of life-laundry meant there are no ‘old’ sheets to be found.  I do have quite a bit of twine though!  The most-favoured products come from Northern Polytunnels (so it must be the proper stuff, right)  Formulated to be kind to the polymers in the tunnel plastic and reputed to deter future formations of the green stuff (watch this space)  I ordered a bottle of Polytex Pro for the outside and Hortisept for the inside.

I applied it with a sponge-headed floor mop, which worked a treat inside and out.  I was a little perturbed by the PPE warnings on the Polytex bottle and I wonder how the Sweet-pea aisle will fair this year but the tunnel is sparkling.

Obligatory before and after shots.

I’m interested to see the difference the increased light levels make to the crops already growing in the tunnel: spinach, cauliflowers, rocket, broad beans and a sad-looking calabrese that’s providing a handful of side-shoots each week.