Can anyone help me to heat my greenhouse?

kippers

I bought a new greenhouse for my garden in the sales in sept that is 6ftx8ft. I want to grow all my veg seeds for my allotment in there (my window sill is just not big enough anymore). I need to buy a heater for the greenhouse but i haven't a clue where to start.

I don't mind spending if i get something that will do the job and is not too fiddly though I don't have electricty so i hope this isn't a problem.

Any help would really be appriciated

Sally_A

First thing - get a Min/Max thermometer in there and see how the temperature fluctuates.

2nd - can you rig up bubble wrap inner curtains over a seed shelf? and maybe bubble wrap over the glass held in place with greenhouse clips.

3rd - although compost is best on the garden with soil underneath, if you are happy to do extra shifting in May, a compost heap will generate heap within your greenhouse (a compost dalek will too).

rhiwfield

Just thinking about the options, some pretty outlandish!

• Sally A had made the good point about insulating your greenhouse plants from night-time cold.
• !!!!!! Strawbridge used glass fragments as a heat sink warmed by the sun, heat transmitted thru tubing via a computer fan powered by solar pv.
• Traditional method has been to use a paraffin heater (parasene) though this gives off water vapour. Or a gas option?
• You could run an electric connection to the greenhouse site via an armoured cable but thats very pricey
• You could erect an internal mini greenhouse (cover it) and place a heat sink in it nightly (hot bricks?)
• Maybe a home made solar panel (old radiator painted black) with pipes running up to the greenhouse which has a (heatsink) water tank inside. Warmed antifreezed water rises into the greenhouse tank during day, cold water falls into radiator. Hmmm legionella, expansion...?
• Battery powered heat mats?

Ah well, Edwardian Farm on

gardenroute

Things I've seen:
1. Tropical plant nurseries wrap bubble wrap around the inside the walls and ceiling to keep heat but allow some light in.
2. Some people use something called a frost buster which is electric but an extension cord would solve that problem, you wouldn't need it for most of the year.
3. Large water tanks in Victorian greenhouses as heat resevoirs.
4. Compost heaps/muck piles used to generate heat.

Your greenhouse may be too small for 3 and 4, but 3 may work a little, water would retain heat better than air.

Burners will generate moisture and so will need ventiliation. Something best reserved for the coldest nights.

Be careful not to generate to much heat. It's important to keep the greenhouse above a minimum temperature instead of keeping it warm as this will harm the plants when combined with low light levels and poor ventilation.

Sambucus_Nigra

Are you going to save enough money with your crops by heating your greenhouse to make it worth the expense; bearing in mind most things don't grow during the winter due to low light levels as much as it is due to the cold?

kippers

Sambucus_Nigra wrote: »

Are you going to save enough money with your crops by heating your greenhouse to make it worth the expense; bearing in mind most things don't grow during the winter due to low light levels as much as it is due to the cold?

I'm only planning on heating the greenhouse during march and only at night if there is low temps in May and April

amcluesent

Beechgrove Garden did a piece on using an old beer cooler as heat-recovery pump from water pipes buried in the ground. http://www.thebeechgrovegarden.com/factsheet/factsheet.php?fact_id=358

rhiwfield

kippers wrote: »

I'm only planning on heating the greenhouse during march and only at night if there is low temps in May and April

Daytime greenhouse heating is seldom needed during the period you mention. March nights are the ones where frost protection will be needed most often and for the longest time.

To save on cost in March my seedlings are put in the large cardboard trays that you see in supermarkets for fruit. At night they are simply brought into the utility room and put back out into the greenhouse in the morning. That way they get the light and the heat when needed at no extra heating cost.

As the seedlings grow, and this becomes impractical, they go out into the greenhouse all the time, but in a covered growhouse and heater on frost protection (belt and braces maybe, but at that time dont want losses)

Sambucus_Nigra

kippers wrote: »

I'm only planning on heating the greenhouse during march and only at night if there is low temps in May and April

I never heat my greenhouse - I'm in the Midlands and everything goes out there in March. And I still get toms growing in November.

If you need protection during these months, then a simple fleece over the top should do.

angelavdavis

I remember Geoff Hamilton showing how to tent off a section of the greenhouse using old bubble wrap to keep your heating costs down and then using a small (ie coldframe sized) paraffin heater for the job. He lined the greenhouse and then he split his greenhouse in half so he only needed to heat half and created a curtain so he could get in and out.

I used to heat my greenhouse years ago using my paraffin heater as I was under the impression it was needed to as I had tropicals in there such as bird of paradise plants. To be honest, even though I still have the same plants, I tend to use my unheated conservatory and only use heated propagators to start things off. Like Sambucus Nigra, I was still picking chillis off the plants in the conservatory in December!

However, I am down on the South Coast so not in a really cold area compared to some on the forum here.

alanobrien

Are you sure you need a heater ? If your just looking to grow veg seeds then a low cost propagator is probably what you need. Grow them into seedlings then move them onto a bench in the greenhouse and cover with fleece in the evenings if needed.

If like me you are interested in tropical plants then the best heating method by far is an electric fan heater. This avoids rot and promotes air circulation. I still use bubble wrap on the greenhouse over winter though, as this helps to keep the bills down.

I also plug the fan heater into a digital thermostat as its more accurate than the analogue dial type they are usually supplied with.