Has anyone yet invented.......???

[Nicos]

I'm trying to get my head around the idea of heating a greenhouse overnight just to keep a few seedlings alive.

The cost must be ridiculously high as they are so poorly insulated

I think it'd be a brill idea to develop some sort of heated stacking system which takes trays of seedlings/small plants.( bit like an insulated blow-away but with more shelves)
You'd use it at night inside the greenhouse when the plants don't need light so they can be stacked on top of each other .
In the morning you'd lay out the trays back on the benches.
Yes- you'd need to watch out for condensation- but that must be 'do-able' surely?????

...or has someone already produced one???

( if not- tis my idea- and I claim copyright!!!!!!)

[Bren In Pots]

I've seem something a bit like that for drying clothes, I'll have a google and come back.

[Bren In Pots]

I've found lots that look like this Nicos :-

JML V0492 Dri Buddi Clothes Dryer - White & Blue

[Nicos]

I wonder if they'd run at say 10-15 C though???

[scarey55]

I put some of my tender plants in polystyrene fish boxes and put the lid on overnight - all you'd need then is a heated mat similar to a wine making one and Robert is your father's brother and Francis is his wife!

[Kristen]

I carry mine from the unheated conservatory into the utility room corridor overnight. I always drop a few during the seed-raising-season

I have a blow-away in the Conservatory, which has a light bulb in the bottom (I'm looking at a tiny greenhouse fan heater for it). That steals some light, but reduces the area to be heated. That means you don't have to get them into daylight, but its not as well insulated as a polystyrene box of course!

I wonder if it is cheaper just to raise the seedlings under artificial light, indoors, than heating a greenhouse, or even a polystyrene box for that matter? Any excess heat from the lighting goes into the house and offsets the central heating cost.

Seedlings can be grown with low energy bulbs.

Lets assume 100W of bulb(s) running 10 hours a day through February and March.

Day rate of 10p/unit - reduce by 45% if you have Economy-7 [i.e. you get 7-out-of-10 hours at half price]

100 Watts * 10 hours per day * (28 + 31) days = 59 kWh

59 kWh @ 10p/unit = £5.90 (or £3.25 on E-7)

Double up for 200 Watt systems etc.

The lighting rigs are not cheap, but you may have spare fittings lying around.

[Newton]

I put some of my tender plants in polystyrene fish boxes and put the lid on overnight - all you'd need then is a heated mat similar to a wine making one and Robert is your father's brother and Francis is his wife!

Is Fanny short for Francis?

[scarey55]

Certainly is

[HotStuff]

Is Fanny short for Francis?

Except he would be a funny auntie as Francis is the masculine form and Frances is the feminine.

[Davyburns]

I have a blowaway inside my proper greenhouse, that is insulated with bubblewrap, and a 2 foot cylinder heater on the floor, its only 80 watts, but it works great for chillies and toms

[scarey55]

Except he would be a funny auntie as Francis is the masculine form and Frances is the feminine.

Oops, silly me

[brigueil]

Overnight no cost heating

I'm new to the forum, so if this is a well tried idea, apologies.

I've built a tiny inner mini greenhouse to sit on my staging which takes about six seed trays and is made from a frame covered with left over bubble wrap from the main greenhouse. The overnight heating comes from a stone slab which lives in the outer greeenhouse all day, absorbing heat, which then goes into the mini house all night, under the seed trays.

[Nicos]

Hi there brigueil - and welcome to the Vine!

Stone slab?- sounds a good idea!
We've talked about water/coke bottles filled with water left in the greenhouse during the day to absorb heat...but a stone slab would presumably take up less space and give off a more even distribution of heat?

Have you tried different types of stone slabs?

[zeezeezed]

Hi Nicos

I dont know whether this will help, but funnily enough I was reading an article about how the victorians overcame this problem before the good old heater came about.

They placed a coldframe inside their greenhouse for to create a mini climate within the greenhouse. They dug a deep hole and filled it with manure, then but the soil back onto the top and placed the coldframe onto that. The heat generated by the composting manure was enough to heat the cold frame.

[Nicos]

I'd forgotten about that ZZZ- my neighbour on our first lottie used to make a hotbed like that and grew strawberries !
Worked a treat!