Winter Greenhouse Regime

[Diane Whitehead]

Yes, I can use that curtain wire trick.  Thanks.

It must be dim inside when you add the shade cloth to the double bubbles
Do the cymbidiums not need much light?

[Darren]

Given our low angle sunlight in winter you can safely line the north side (and possibly the east?) of a greenhouse permanently with 5cm thick polystryrene sheet sold for insulation. In fact if this is then either left white or covered with reflective film or foil (or old mirrors in my case) this will actually increase the light reaching your plants by reflecting back the sunlight coming in from the south. My crocus now grow straight up rather than leaning to the south.  This reduces the area for heat loss by a considerable amount, and it is on the sides which get the worst of the cold winds in the UK too.

I use an electric fan heater with an external thermostat which is set to maintain at 1 to 2 C. Bubble plastic is applied to all sides and roof when temps below -3 are forecast, to prevent the heater working too hard. The glass and plastic alone will keep out -2.

The lowest external temp I've measured here so far this winter is -4.4C which I know is milder than most of you have had.

[Maren]

Hello Diane,

there is a reduction of light, you are quite right. for that reason I use the lightest shade netting available. I found one that gives just 20%, the cymbidiums seem OK with that. I am also considering using pea netting over the bubble instead of shade netting. that's a bit harder to fix and may be less effective due to its flimsy nature.

But I'll try it next summer. At present I can't get out of the house, snowed in solid. I anticipated this and stocked up with food, but I miss my daily newspaper.

[ian mcenery]

A very interesting thread with some very ingenious ideas. My old greenhouse was a very old (40 years) and small Alton in cedarwood now residing at the allotment in pieces waiting to be erected. This had lots of gaps to let out the heat brought about by my miserly maintenance. Previously I had little use for a greenhouse as I always believed that the best place for plants was in the garden where I had less chance of killing them and they looked more natural. So my greenhouse prior to this was used mainly for propagation and overwintering young and very tender plants and was therefore fine. Joining this Forum and having a little more time on my hands  made me get more interested in bulbs and realising that many winter bulbs are best enjoyed in the comfort of somewhere protected from the weather was good for the both of us.  Having decided to invest the kids inheritance I bought a new 12 x 8 custom jobbie on a half brick base with windows to all panels (auto in the roof) the thought being to allow good ventilation hoping that I could leave these open all year round. Well after the current bout of weather it seems this falls into the category of "the best laid plans of mice and men". I had also decided that I would buy any accessories I might need at the time so as to get over the pain of parting with my money. As a result I also bought plunge staging, a thermostatically controlled fan heater and since I needed a light a mercury vapour lamp.

I am growing mostly Cyclamen, Crocus, Narcissus and a few other things mostly bulbs. The problem faced here was that many of the plants will take quite low temperatures whereas Cyclamen rolfsianum and  persicum and a few other tender plants do not like cold at all. What I have done so far is to set the fan heater to come on at 0 centigrade (32F) and God only knows what it is costing- but there is at least some peace of mind well at least until the meter is read.

In terms of soil warming cables I also have a few cuttings which I have been trying to root so I have used a soil warming cable on these but like previous comments this dries out the sand plunge very quickly- I only noticed this morning 

My greenhouse is unfortunately in a semi shaded position (my neighbours trees) and does not get enough light at critical times meaning the the plants have a tendency to lean toward what light there is and as they quickly root into the plunge I do not want to damage the roots by moving these- well the cyclame are OK but not the others. As an experiment I am  using a mercury vapour lamp a timer switch which comes on for a couple of hours before dawn giving the plants a little more daylight

[ArnoldT]

Ian's comments about spending the inheritance reminds me of a bumper sticker I saw on a fancy sports car.

"My heirs will walk"

[ian mcenery]

Ian's comments about spending the inheritance reminds me of a bumper sticker I saw on a fancy sports car.

"My heirs will walk"

I believe the term used now is I'm off  SKIing

Spending the Kids Inheritance 

[PDJ]

The one thing that surprises me is the number of people who don't heat their greenhouses then complain there whatever has died.

I keep my 11 x 8 greenhouse at 5'C all through the winter with an electric heater, there not that expensive when you consider the cost of the plants.

[Ezeiza]

Well, I have read a lot of false information concerning the supposed hardiness of South African bulbs.  No wonder one would lose them by following it.

[David Nicholson]

The one thing that surprises me is the number of people who don't heat their greenhouses then complain there whatever has died.

I keep my 11 x 8 greenhouse at 5'C all through the winter with an electric heater, there not that expensive when you consider the cost of the plants.

Do you line it out or take any other action to keep costs down?

[David Nicholson]

Well, I have read a lot of false information concerning the supposed hardiness of South African bulbs.  No wonder one would lose them by following it.

Alberto, it would be helpful if you indicated examples of where you disagree with what has been written so far please

[PDJ]

I keep my 11 x 8 greenhouse at 5'C all through the winter with an electric heater, there not that expensive when you consider the cost of the plants.
[/quote]

Do you line it out or take any other action to keep costs down?
[/quote]

I don't line it as it only reduces what little light is available this time of year. 

[Tony Willis]

The one thing that surprises me is the number of people who don't heat their greenhouses then complain there whatever has died.

I keep my 11 x 8 greenhouse at 5'C all through the winter with an electric heater, there not that expensive when you consider the cost of the plants.

I do not complain I just  replace them with hardier subjects.

[PDJ]

A tip from the building trade:

To prevent roots freezing and to increase the temperature.

A method I used before going over to electric heating.

1.  Thermal boards used in building either during the construction to fill the wall caverties or as secondary insulation.  The boards range in price from £5-£30 and you lay them on the floor and staging.  They require holes making to accommodate supports the same thickness as the boards so heavy items can be placed resting on the supports. 

2.  A more professional job can be done with planks across the supports.

3.  WARNING remove the insulation once the weather warms up or you can Cook your plants.

Similar to lagging outside pipes to prevent freezing. 

[PDJ]

Forgot to mention the boards are available from builders merchants or B & Q.

[Diane Whitehead]

Well, I have read a lot of false information concerning the supposed hardiness of South African bulbs.  No wonder one would lose them by following it.

  Well, that year I was awakened by strong winds and slashing sleet and heard the greenhouse door blow open. I just snuggled down in my warm bed and didn't go out to fix it.  So it wasn't bad advice that did in my South African bulbs, just my cursed need for comfort.