This Forum will close on Wednesday 27 March, 2024. Please refer to the announcement on the Discussions page for further detail.
Greenhouse query
InTheMoorlands
Posts: 161
Anyone any idea what the ideal temperature should be for a greenhouse in winter, should there be such a thing?
Ours contains bonsai and succulents brough in from the garden plus a few vegetables in trays. I’ve a strip heater that kicks in with a gentle heat at 5C. Last night’s low was 2.5C. I have another small electric heater for when the outside temperature drops to below freezing. Outside daytime temperature is currently 1C!
Just wondered what others were doing.
At about 750 feet on the western edge of The Pennines. Clay soil.
0
Posts
The minimum temperature is set by the minimum required by the most tender plant. You could have just a warm zone.
In my unheated greenhouse in winter I have: bonzai, but more to protect the pots; evergreen agapanthus; Rhododendron cubitii, more for protection of the spring flowers; hydrangea cuttings up to 3-tears old; Aeoniums; young Oleander; mind-your-own- business, houseplant balls; mint; French tarragon.
The temperature where measured just below the eaves can drop to that outside, but for a much shorter time.
"Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
Pennines at about 750 feet. It can get a bit chilly at times. One year the cold killed two mature trees in the garden. The man who took them down said that he was taking down a lot that had been killed by the cold in this area.
What I assume to be the tenderest plants are the succulents which are on wooded boards just off the floor. This must be the coldest part of the greenhouse, but they are too heavy to put any higher. Some succulents can stand the cold but I'm not too sure about the ones we have. My aim is not to let the grenhouse go below zero, but I'm seeing more and more posts about cold greenhouses, presumably due to energy costs, so I wondered what others were doing.
I used a 1000w heater to keep the temps up to about 10C. That was in March and April when I had seeds in a small propagator.
I'd guess that may have used up to 10 units/day which would be about £3.50 a day at current prices.
If your greenhouse is bigger or more exposed it would be more.
The heater would likely be on more during the Winter too.
I only used mine to keep seedlings alive in Spring
A lot will depend on winter temperatures of course.
We rarely even have frosts where I live over the last few years
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.
Yes, exactly. Thinking about it I realize that there cannot be any standard answer.
Just one point though. Would there be any great benefit in keeping the greenhouse warmer than just above freezing? For years I've just been concentrating on stopping the bonsais and succulents from freezing, but I am now doing other things.
Besides succulents and bonsais, I also have turnips, spring onions and rocket in trays. The turnips look healthy but have been in for two months and I can only see one bulb out of ten plants. This is my first year at growing veg. in the greenhouse in winter so sorry if this is a bit of a daft question!
I don't have any bonsai or succulents, so can't help I'm afraid.
I'm sure you'll get more answers soon
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.
Re Bonsai - depends what you have. Keeping the shallow pots and roots frost free for the hardier ones is the most important I think. To a certain extent, you can do this by using internal protection - lined boxes etc. - not always attractive admittedly but if you are more interested in keeping them alive rather than the look of it, it would help. Again, with succulents it depends what they are and their position in the GH - some form of internal protection may help.
Given the cost of all forms of fuel at the moment, the less you have to heat the GH ( whether part or whole ) would obviously be better.