Keeping things cosy

Hi, all. So I'm a novice gardener and I've started experimenting in the greenhouse.

During sunny (not even particularly warm) days, temperatures in my greenhouse can reach between 40-45oC, which is fine. At night time however it doesn't retain warmth at all and drops dramatically to below 10oC.
Firstly - is this okay? I suspect not because my tomatoes seem to be struggling with the currently damp, chilly weather (so much for summer!) and the leaves are developing brown spots.
I would like to install some kind of heater for night time, but there is no possible way of having anything requiring a powerline in there, because it was built too far away from the house.

I'm looking for advice on keeping my chilly plants on cold, wet nights. Whether they're ideas about warming the greenhouse itself or keeping my containers and growbags warmer, I'm interested

 

Thanks for your advice, JWK - I have been careful on warmer days as I knew that it was getting too hot in there...on warm days I leave the door and window open to get the air moving and cooler, which seems to be working. Come late July I'll probably be on here again asking about how to cool things down! haha

I hadn't actually thought of shade though, to be honest...I'll have to look into the things you mentioned. My local Homebase sell Greenhouse Shading so I'll have to invest in some before summer really arrives.

For now covering things seems like the most sensible plan, doesn't it? Then look more into it when the weather starts to cool down again.

 

Hi leafos,

Sorry, I was so busy modding about earlier that I didn't say welcome to Gardeners Corner.

I'm finding Thermal Mass is a good way to go. The temp in my cold frames stays at 14c overnight due to the bricks absorbing the heat during the day.

I use concrete blocks on the table under the south facing window in my caravan to heat that at night too, will work better when I get around to painting them black:DOH:

It still works good as a radiator as it is though.

I'm going to apply the same principal to the greenhouse, a low wall of lightweight blocks on the north side should provide a free solar powered heater, taking some of the excess heat during the day and releasing it at night.

 

You'r chillis will survive as they are reasonably hardy one established.
Cold shouldn't now be a problem. I'm about 500 miles to the north of you and my tomatos, cucumbers, peppers and chillis are doing fine in an unheated greenhouse and a small polytunnel.
I've lost more plants in the past due to excessive heat rather than cold.
As John says you need to ventilate and put up some form of heat shield, and don't worry about reduced temperatures at this time of year.

Ziggy's comments regarding thermal mass are to the point though there's not much you can do to exploit the potential in a normal greenhouse without a bit of engineeering. Mine has a concrete floor and brick wall at the back and I've painted half the floor and the wall black in order to absorb and store more heat during the day and release it at night. A bit like a night store CH system!

 

It sounds like Hell down there in the deep South!.
Whats 35C?
Plunging below10oC at night? - I often don't see 10oC during daytime up here.
We can't think about starting with Tomatoes, Cucumbers etc. until late April because of Frosts etc. and they have to be tough enough to withstand night-time temps of below 5oC even in June.

No wonder I seem to be behind others on the Forum. I need heating installed. There's not much call for cooling paint though.

 

I agree with all the above advice .I usually take out the top row of glass out down each side of my greenhouses around the end of June till Sept .
Dave

 

Thanks for all your advice. Putting materials in that absorb and then radiate heat hadn't occured to me - that's clever! Would a black barrel of water work in a similar fashion?

 

It might but I think its not so efficient as a brick or block.

Got me thinking about firebricks now, enthused by Daves post, with the black painted blocks.

Bit more expensive, but they won't be once i've cracked the mortar recipe for them:WINK1:

 

It is hell, the solar water heating nearly boiled last week, 81 centigrade:DOH:

All sorts of moaning coming from the system, pressure vessel took up all th excess though