Preventing snow damage (our blog by horticulturalist Peter Whyte)

The opera isn’t over until the fat lady has sung, and winter isn’t over until danger of heavy snow is well past.  The problem with snow is twofold: it is so heavy when it lies that it can damage or distort greenhouses, and more damage can be done by trying to remove it.

Snow is light in thin layers, but as it builds up its weight increases quickly.  Ten or twelve centimetres of snow can melt down to one centimetre of water which doesn’t sound much, but over the area of a roof it’s enough weight to do damage.  It’s especially a problem if the wind drives it on to one side of the roof in a lopsided pile, as the uneven weight distribution can bend the framework over sideways.

Taking it off makes sense, but must be done carefully.  All cladding, be it glass or plastic film, is more brittle when cold.  It’s all too easy to break a pane of glass by touching it with a metal implement or puncture polythene cladding with a sharp object.  Use a plastic or rubber-tipped shovel or a soft brush, or on polythene tunnels a strip of cloth or soft rope sawn gently back and forth across the top.

Clear a glasshouse in the same way as installing the glass in a new one.  Don’t do all one side and then the other, as the weight can distort the frame.  Remove a small amount of snow from each side alternately, and work from one end to the other.  Wear gloves over your coat cuffs, or you might get your arms soaked in melting snow!