Precocious flowering - a warning

[Dionysia]

Graeme, they're basic 3 speed 12 inch desk fans that you can buy at DIY stores and similar. They can be difficult to find in the winter as they're seasonal for most users but I did recently buy a couple of back ups off Amazon, just in case one breaks down this winter.

[Mark Griffiths]

thanks Paul, I'm not growing Dionysias but sometimes have similar types of issues with the few things I do grow like Primula allionii - I did have one very nice plant which was completely covered in flowers - it must have sweated underneath because I then lost almost all of it to rot - this was before any flowers faded.

[Steve Garvie]

Paul - could you post some pictures of the fans - I have lost a couple of dionysia this year and it is really frustrating - I only get in that alpine house once a week and by that time its usually too late

I'm not sure how long this eBay link will last but I have found these fans to be very useful: http://www.ebay.co.uk/itm/Clip-on-air-fan-circulator-cooler-hydroponic-grow-room-tent-office-desk-fan-6-/390705242971?hash=item5af7d8e35b:g:nykAAOSwuWVWFS6s

They easily clip onto internal framework in the greenhouse, are surprisingly resistant to humidity and whilst having a low power consumption produce good airflow. I have used these types of fan on Ophrys and South African amaryllids in a greenhouse extension which has poor ventilation (to conserve heat). It is best to purchase a few and place them such that there are "criss-crossing" airflows -the swirling and airflow interference patterns ensure excellent air movement. Mine are controlled by a plug-in timer (has the facility to switch on/off in 15 minute increments over 24 hr). I am only now using these fans on cushion plants in the "open" alpine house but despite the continuing unseasonably mild temperatures with excessively high humidity I have been able to halt the spread of botrytis on my small collection of Dionysias.

Another more expensive option is to use a dessicant dehumidifier. These have only recently become available at an affordable price. Basically the technology is based on humid air being sucked in over a zeolite disc which very effectively absorbs the moisture and is then "recharged" by a small heating element in a regular cycle. A cheap unit will cost about £130+ but can effectively remove 8L of water per day -more than enough for a large greenhouse. Unlike compressor dehumidifiers these units remain efficient even at low temperatures.

[Maggi Young]

Those SwiftAir fans are  available via the Amazon link at the foot of SRGC pages :
http://www.amazon.co.uk/QUALITY-Office-Hydrophonics-Cooling-Fans4less/dp/B00EUZB4JW/ref=sr_1_fkmr1_1?ie=UTF8&qid=1449782493&sr=8-1-fkmr1&keywords=SwiftAir+clip-on+electric+fan

[Dionysia]

Good to see further tips being given. I adopt a lower tech method of reducing moisture. Every morning I check for condensation on the windows and remove with a Kärcher window cleaner. Only realistic if you're retired with a tolerant spouse.

[Graeme]

Another more expensive option is to use a dessicant dehumidifier. These have only recently become available at an affordable price. Basically the technology is based on humid air being sucked in over a zeolite disc which very effectively absorbs the moisture and is then "recharged" by a small heating element in a regular cycle. A cheap unit will cost about £130+ but can effectively remove 8L of water per day -more than enough for a large greenhouse. Unlike compressor dehumidifiers these units remain efficient even at low temperatures.

Have got one of these in a shed somewhere - I bought a battered second hand one when we were trying to dry out the plastering in the house - I had never ever considered using it in one of the alpine houses - thanks

The fans look good too - I had been looking at ones which look like a drum and hang from the ridge bar - but they get in way or the lighting

[Martinr]

Another good source of desk fans is to find your local auction house that deals in the bottom end of the auction market. You can usually get working 12" fans for about £5

[meanie]

Thank you for this thread.
As someone who is slowly building up a collection of winter flowering Salvia it is something that I am vigilant towards. Thankfully so far this  year the greenhouse door and windows have barely been shut which helps but I have been extra cautious too. I wipe the glass down at least once a day with workshop paper towel and have newspaper on all flat surfaces which is chucked every two or three days - small measures which offer small but useful benefits. The hardest part was leaving all my Echium seedlings outdoors as they all exhibited signs of infection as early as October outdoors.

[Mark Griffiths]

just to add I've started using a dehumdifier which started after a decade to become too noisy for the house. Of course now it is out in the greenhouse it is silent. I've run it on foggy days but so far haven't been able to do enough measures to see what the effect on humidity is. It does put out some heat which is ok for me as most of the my plants are cyclamen but might be an issue for others.

[TC]

I am rather fearful of mains electricity in a glasshouse.  At one time I thought of getting an electric fan from a car and connecting it up to a twelve volt battery in a garden shed and keeping it topped up with a mains battery charger. A cable carrying 12V would not present any danger. I think it would work but have yet to get round to it....like most other ideas !

[Mark Griffiths]

I had an electrician wire it up. From the house with armoured cable, to the garage with a seperate fuse set to the greenhouse with plenty of power available for heaters, light, fans etc.

[johnralphcarpenter]

I did the same in the polytunnel.

[TC]

I have 20 feet of armoured cable left over from the wiring job to my shed.  I have a consumer box fitted with two ring circuits and lighting circuit.
I have fitted a PIR controlled lamp connected to the ring circuit with a weatherproof outside switch.  Fitting the electrics does not bother me but routing out a channel in the concrete base for the armoured cable seems too much of a bother.  Anyway, the costs of electricity would put me off.

[Martinr]

My builders overcame that little problem by bringing the armoured cable up just short of the base and mounting a double outdoor switch on a 4x4 post. An appropriate extension lead is then used to route the power in via one of my louvre panels, with a suitable drip loop of course.