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The Beechgrove conservatory one day in Feb 2009

In a week when the forecasters reckon we are going to see a significant drop in temperatures and probably a dump of snow, my mind turns to the safety of the greenhouse,Ìý the conservatory and the plants therein. In the that means a mixture of a few tender shrubs, half-hardy perennials, pot plants, stock plants and winter salads.

As snug as a bug in a rug on that February day 2009

In the television garden, apart from the structures in the ‘Glasshouse Village’ (so named because we have five greenhouses, a Keder tunnel, several cold frames and a potting shed in a cluster) we have a rather splendid conservatory at the top of the garden. In past seasons we have moved all pots and containers into this large space, which we insulate with a bubble polythene tent and maintain at a minimum night temperature of +5degC using fan heaters. The other smaller houses are shut down until spring.Ìý The system has worked well.

Sadly, the conservatory is beginning to show it’s age, (it was moved from the original Beechgrove Garden when we moved to our new site in 1995). Hopefully we can affect the necessary repairs over the winter months and in preparation for that this winter, the team behind the scenes have been reversing the process – moving as much as we can into the Glasshouse Village, leaving the conservatory empty.

Plants are going to be packed in to smaller spaces and therein lies a major danger – excessive humidity which in winter we tend to call DAMPNESS! As most gardeners will know that means one thing, the scourge we call Grey Mould caused by the fungus Botrytis cinerea.Ìý There is one principal cultural control for that – ventilation, or more precisely, positive air changes. BUT, we don’t want to open up the greenhouse and let the temperature drop say the penny-pinchers. It is better for the plants to be dry and cold rather than wet and warm, say I.

Whilst we may highlight the dangers of snowfall and frost, in our climate the major dangers are caused by short days, poor light, low temperatures and high levels of condensation, moisture, humidity.Ìý In the enclosed atmosphere of a glasshouse or polytunnel packed with plants almost all in suspended animation, Grey Mould can cause havoc.

My answer is to pick over the plants as often as you can removing dead and dying foliage, water sparingly early in the day, don’t spill excess all over the place and once or twice a week leave the door open for an hour in the middle of the day to change the air, obviously choosing a time when the air is drier and perhaps there is a slight breeze.

Jim McColl presents ´óÏó´«Ã½ Scotland's the .