Plants in the Alpine House or Cold Frame: Ventilation in the Alpine House
Started by: Richard Jeffery
To introduce fans or not?Go to latest contribution by Richard Jeffery, 24 January 2007, 23:36. Go to bottom of this page.
With the extremes of heat in the summer months and now damp in the winter, is it time to introduce electric fans into the alpine house? Whilst it seems like a good idea in principle, in my case I would have to lay 50 metres of electricity cable to reach the house and this is almost impossible to do because of the layout of the rest of the garden. Not only that, but it would be a pretty expensive exercise too. How many members use and benefit from fans, and for those that don't, what other alternatives are there for increasing ventilation without letting in too much damp?
I move a number of more vulnerable plants to a lean to greenhouse attached to the back of my house during winter so I can have a fan working on them. Like you my alpine house is a long way from the electricity supply and on the other side of a brook. The 'fan assisted' plants do well while botrytis attacks a number of plants every year which don't make it high enough up the priority list to get space in the lean to. Eventually I will have to bite the financial bullet and install an underground cable
Does anyone know of a solar powered fan system, would avoid all the problems of laying cable.
There are certainly solar powered fans out there, two wests & elliott used to do one I think. They are usually of pretty low power output and hence air moving capability and, of course, don't keep going at night. As my Alpine house is at the bottom of a steep North facing slope which gets no sun at all at this time of year probably wouldn't be too efficient during the day either. Might be good for some summer ventilation though.
I have used a fan in my "alpine house" for 20 years or more, but I laid power (~80')to the greenhouse 40 years ago, so it is not a problem. Just for a fan it does not need to be a permanent installation. A suitably protected or visible extension lead would be OK for temporary use in mid winter, and there are always low voltage fans from a transformer in the house.
Don't I remember massive fans in the end walls of the alpine house in Edinburgh botanic, and you could not hear for fan noise in the Wisley behind the scenes large house before the recent changes.
Brian, what type of fan do you use? Large or small, oscillating or fixed, and do you use it day and night or just overnight? It must be difficult to decide when to use it at the moment with such changeable weather conditions; mild, wet and windy one day, and cold and sunny the next. Richard.
Sorry for delay Richard. I have not logged on here recently. I use an instrument ventilation fan, mainly because I some years ago I had a free supply of part used ones. These are ~5" square and 1"+ thick. They are good enough for only about a couple of yds sq in front of them, but I only have a very small unheated house, and that has 4 sq ft of permanent ventillation even when the door is closed, under the door and a removed side window. My frost free house has a permanently running heater fan (Parwin) summer and winter.
I use a simple 24hr timer, 15min segmented timer, set for 15mins an hour or so at night, 15 on and 15 off during the day. If the door is wide open and it is windy I may turn it off, but usually I forget. It is about 20 watts from memory.
You can improve things by plant sorting. I grow a number of winter growing plants, e.g. bulbs, which means green active plants alongside dormant cushions. This is probably why the house is always too humid in winter, and I cannot grow any decent sized cushions before botrytis arrives. If I separated winter growers from spring summer growers I am sure I would have less trouble, but with limited space something has to give.