Heating a greenhouse

[bojo7]

Hi!
My new greenhouse (8foot x 8foot)is a fair distance from my house (20 yards) and has no power supply. I just need to provide a little heat on sub-freezing days. I was considering a portable power supply (around £150 from Amazon) and a low-wattage (40W) greenhouse tube heater (£30 from Amazon).
I wondered if anyone had any experience of this or any alternative solutions?
Thanks!

My DF just has some candles in some sand in a metal tray on the floor of his greenhouse. I dont know how safe this is but he has done it for years to "keep the frost off"

Thanks tree frog, but would you believe that will not work for me because I will have tree frogs in the greenhouse!

Oh my goodness! Now I need a photo of your frogs 🐸

----Here you go!

Love it! And I dont know the solution to your heater problem but hopefully you figure it out soon so the little guys can stay toasty.

Several things to consider: do your tree frogs (how lovely!) have free run of the greenhouse or are they in an enclosure within? What temp do they require to survive? Then you need to calculate how much heat is required to maintain that level in the coldest weather in your greenhouse ( which will depend on where you live in the country.)

A 40 watt tube is most unlikely to make any difference in an 8 x 8 foot greenhouse, more suitable for a cold frame, I think. To heat a 6 x 8 greenhouse to about 5°c would probably require a 1.5 or 2 kilowatt heater in winter (depending where you live).

I have no knowledge on portable power supplies I’m afraid, but I don’t think one would be adequate.

Love the frogs 🐸 ❤️
Can you run an extension cable to it or does the heat source have to be totally independent from the house?

I like this question as have an unheated greenhouse but I'm truly invested in yours now I've seen those wonderful frogs! How lovely and i hope you keep them happy and warm ! (Sorry I'm no more use than that!)

I recommend a remote thermometer, which has one thermometer which you put in the greenhouse, and it communicates with the other that you put in your kitchen or living room. If the temperature drops below 0 in the greenhouse one, the indoor unit flashes and warns you to take action.

Thank you, Nan. Yes, the intention is that they have free run of the greenhouse – it is for them. They are European tree frogs and the ones I have are from Northern Europe and most should survive the British winter including being frozen, but I usually keep them inside during the coldest months as not all would survive. Just above freezing is my target temperature. I am in South East England, so not the worst winters. But I think you are probably right that a 40w heater won’t do much, but it might be enough.
Thanks Hoho, yes I might have to do this and just use the cable for very cold days. Just not sure about having something that long and it being weather proof.
Schoolrefusa, yes, they are wonderful, and I have friends who have kept two successfully for years in an unheated greenhouse, but I don’t want to risk it. Of course, there are claims that these used to be a native British species and there are some wild populations in Southern England, probably from escaped pets. Mine will of course be secure in the greenhouse.
Ah Sleepy, just googled power bank with solar panel and that is an interesting option. Problem is that heaters need more than lights, but it may work.
And thank you, Mere. I think a remote thermometer is a good idea, if I can do that without a power supply. The house wifi does reach that far I think.

I wouldn’t have thought a heater, even a 40w one, would run for very long powered by a power bank. An extension lead might be a better idea.

Which power bank were you looking at?

Thanks user, I was thinking about the first one on this list, but only because it is first on the Amazon list.

https://www.amazon.co.uk/gp/bestsellers/outdoors/4370158031/ref=sr_bs_3_4370158031_1
It does suggest it can do 4 hours of 60watts on a charge.
Maybe I should try a calculation!

Running an extension lead to the greenhouse would give an electrician apoplexy! Not at all safe, and could be dangerous. It would need o be totally waterproof (including the sockets) and have an RCD.

If you have foxes around as I do (also in he Southeast) they just love chewing electric cables, I have had two expensive greenhouse heaters ruined by the local fox chewing through the cable.

I do have foxes - so I think I will forget the cable idea. I know cables can be put underground but that would be a massive job, so off the table.

@bojo7 have you looked at the cost of getting power to the greenhouse. We had to get external power to our garden office. 8 m of cable - it was much cheaper than I anticipated.

My grandfather used to use candles as well.

I think charging and lugging that power pack back and forth (which will cost a fair whack to be enough to run a heater for any amount of time) will be a nightmare...

How about a little gas heater - if you check out camping shops (or amazon probably) they have options.

I have a gas camping shower which is honestly better than my electric one at home!

I would worry about a combustion heater killing the frogs with CO.

I’m curious about the foxes chewing extension leads. We have had a lead running out to a classic car to keep the battery charged for over ten years and it has never been chewed. I know we have foxes visit the garden because I saw one last night.

And thank you, Mere. I think a remote thermometer is a good idea, if I can do that without a power supply. The house wifi does reach that far I think. They run off batteries and use bluetooth I think for communication. They don’t use your wifi. My greenhouse is 20m from the house, and that copes.

You can put cables above ground, on poles, I believe. But it needs a Section P certified electrician, as does an underground one. Ours runs through an underground channel that we put in at the same time as we tarmaced the drive. It’s an armoured cable running through a tunnel.

Gas heater outside the greenhouse taking heated air or water in pipes into the greenhouse? (You may feel it’s simpler to get an electricity supply).

Relocate the greenhouse against the house wall.

Have you insulated your greenhouse with bubble wrap? Get the proper horticultural stuff as it is thicker and UV stabilised. About 20 quid for a 10m roll from memory.

Thanks Ibiza, I might just get a quote, just assumed it would be a big job.
Recycle, user, I discounted the gas/propane options in case of fumes, as you suggest user. Don’t know if this is unnecessarily cautious, but a frog is more vulnerable to fumes than cold.

Definitely getting a thermostat Mere, maybe I can get Alexa to let me know if it is freezing outside!
“Relocate the greenhouse against the house wall.” This made me laugh, it has taken all summer to build this greenhouse and I was thrilled when it was finally cemented in place last week.
And thanks Another, might look at bubble wrap, perhaps heavily insulate one corner.

Greenhouse paraffin heater.
Made for the job, cheap and no messing about with power supplies.

I doubt paraffin fumes would be good for the frogs, also expensive to run, and not easy to get supplies these days. Maintaining the wicks too, to avoid soot everywhere.