[Stree]

Those white pots on the shelf in the left hand window......sweetpeas.

[devonbarmygardener]

Your sweetpeas look identical to mine Stree! Even the pots look similar!

I too have a greenhouse and utility full of seedlings - feeling very happy to live in the warm south west!

pouring with rain mind you!

[cadalot]

Pictures are worth a 1000 words - where did you get the silver foil bubble wrap insulation sheet?

I thinking I may line the coldframe I'm building with that

[ally]

Excellant construction ... will set my retired dad a new project. Do you know what temp it keeps? ( i understand it will vary but as a guide).
Today I am glad I sat on my itchy fingers and busied myself with mummy jobs yesterday as I have woken up to a patchy white garden ...... 

[Stree]

I can answer those questions a little later today, just got school run and a car for MOT to do first!

[DD.]

Pictures are worth a 1000 words - where did you get the silver foil bubble wrap insulation sheet?

I suspect that it's radiator reflector foil, such as this:

Radiator reflector

If I may be allowed to comment that I think those seedlings could do with a little more light, especially the ones at the bottom.

[mumofstig]

Sorry, but I was just going to say the same thing about the leggy seedlings in reply # 25 especially.

Get them out into the main greenhouse as often, as soon, as you can - if they get too leggy they'll never make good plants   
Some sunshine would help all of us this year - light levels are terrible everywhere 

[BabbyAnn]

light levels are terrible everywhere 

Normally all my seedlings go in the sunny south facing back bedroom where it is warm and bright even for March but it's been so dull and chilly that I've had to rig up a grow box with additional lighting to get the chillies going.  The onion seedlings on the windowsill are fine, but the 1st batch of tomato seedlings are 

[Stree]

DD, Mum,

Please read the full thread where I explain that I am fully aware that the conditions are not optimal for these seedlings because it is too early in the season, the day light length is not enough yet. this is an EXPERIMENT to trial the efficacy of the heated propagator box I built, using sample batches of seed. Now that I am confident of its ability to germinate seedlings requiring good bottom heat I can prepare to sow the full batches at a more appropriate time. Most of the seedlings are in small cell strips containing 6 cells and I am quite prepared to treat the whole of this batch as sacrificial.
As for the foil, if you wish to use radiator foil then that is up to you, I am using thermal insulation foil as used in loft spaces etc which is available by the roll in Wickes or B&Q and suchlike. This was originally developed by NASA for use in the space shuttle to counter the dramatic cold of space and the searing temperatures of re-entry where space was at a premium but effectiveness needed to be optimum for the space taken.
I have studied pics of the shuttle interior and I failed to see any radiators in it. Where would they put the flue pipe for the combi boiler anyway?

Ally, the temperature is controlled by the probe thermostat, this protrudes 10 inches or so into the upper sand bed. This will enable you to preset a temp. But this is very slow to respond to any manual setting so must be altered only gradually and as necessary. Trial and error is the only way here.
A lot of what heat output is achievable is determined by the spacing of the soil cable runs, 4" spacing will run a lot cooler than 1" spacing, mine runs at approx 2" spacing and I can get 32c if require,  20c to 25c is usually sufficient for most seeds.
My unit is approx 40" by 15" and at 2" spacing I require a 6meter length of cable and 2x 25K bags of silver or paviour sand. So these boxes are very heavy when completed, make sure your staging is up to the job.
The sand in mine is sat on a 2" thick polystyrene base so no heat loss from the bottom and the inner sides are again lined with the silver space blanket.

[mumofstig]

That's us told 

I just didn't want anyone to think that those seedlings were growing as they should be 

[Stree]

Aw, it was not meant to be a telling off, just I suppose I am very formal. Sorry

[New shoot]

Well I'm glad I resisted the urge to sow anything else just yet, having woken up to snizzle (snowy drizzle) and now looking out at a steady fall of snow    Luckily it is not settling on the roads as yet 

The met office reckon temperatures should be returning to more seasonal norms for easter weekend.  Cross everything now folks and get ready for a sun dance   

[cadalot]

George if you are looking down we need your HELP

yGKPHFrHVVY

[surbie100]

There's a good clip on how to build a heated propagator here: http://www.bbc.co.uk/gardenersworld/video/toby_30minfix/heated_propagator.shtml (shamelessly lifted from Angelavdavis)

If I had space I'd build one. Until I get that house with a garden I'll settle for setting up an extra shelf on my windowsill for seedling overflow (and baking a cake to distract OH!), and start practising that sundance! 

[New shoot]

How are your Bigga peas doing in the cold Surbie?  I bought a pack when I went shopping last week, but haven't sown them yet.

Are yours inside or out on the balcony?  Thinking they may scratch an itchy finger or two until I can eventually get sowing for real