already thinking of 2017. Help me with cold frame setup.

[arrgh]

Hi
 
This seasons plants are all transplanted, and just waiting for mother nature to do its thing.  So I'm already thinking of how to plant next year.
 
I'm wanting to plant in a cold frame, with heated soil. 
 
I'm going to give a bit of personal history first, to explain why I want to do that. You can skip the first few paragraphs if you just want my questions.
 
 
I have been planting from seed for a couple years. Last year I planted in mid January, and kept inside until a couple weeks before planting at end of may(in zone 6).  I have very little room inside, and not able to buy best of lights. So My plants were all leggy and extremely small. 1/2 my plants died before time to put out. Then I had trouble hardening off, and lost another 1/4.  Once I got the survivors in the ground I had no issues and they grew huge, and had more peppers than I could even use.  But still was stressful, constantly worrying about them.
 
This Year was MUCH better. I waited until mid February to start.  Then built a homemade cold frame from concrete blocks and old storm door. I put Seedlings(in solo cups) into cold frame at beginning of April.  I brought them back inside on a couple of coldest nights. But mostly just left them there.  Since they were getting some real light they didn't get leggy, and I didn't lose a single one!  So this years procedure works, and i will probably do most of my  plants this way next year. But would love to do a test with some plants just to see if I can make plants get through the winter outside.
 
I'm thinking now that If an extra month and a half in the cold frame does this well, how would 3 months do?  So I'm thinking of trying to heat the soil with a underground heating cable and planting seedlings first in paper towel, then directly outside in the heated soil. Since google isn't giving me much info on this, I expect it is impossible. But would love to find out differently. Both because not planting inside would save me room, and probably mainly because I just think having peppers outside, with snow all around would be cool
 
 
So now to the questions, and the specifics.
 
I've thought about this for at least an hour now(see I've put a ton of thought into it And have already thought of a few issues.
 
If I planted in solo cups on top of soil, I would get no use from the soil heater, so that is out.  But if I plant in the soil itself. The roots would grow down and wrap around the heating cable, and depending on how close I plant them would wrap up in each other. So when I tried to dig them up I would be damaging them, and probably the cable.
 
The only solution I can think of would be to put about an inch of soil on cable then put 3 or 4 inch thin square seedling pots in with all empty spaces filled with soil, and the top of pots even with top of ground.
 
So now, finally the questions.
 
 Is this even remotely possible? I've found web pages talking of planting lettuce and other cold weather plants, but not peppers.
 
 
If it is possible How early would I be able to start the plants?
 
Would the heat from cable travel up through the pots?
 
Would the heat from the sun, and from the soil keep the air inside at least at a passable temperature? Or would I also need to come up with an air temperature solution?
 
Are there any webpages with information on this. All I can find is either coldframe or hothouses, But not the kinda hybrid I'm thinking of.
 
Thanks for any information.  
 
This went a bit long But hopefully I at least gave people something to laugh about. The musing of a bored, and probably stupid rank amateur gardener.  
 
 
 
edit      sorry meant to put this in growing forum.   feel free to move it there if you wish
 
 
edit 2   I searched some more. Finally came up with the correct google key words  "heated propagation bench".
 
https://www.quickcrop.co.uk/blog/how-to-make-a-heat-bench-propagator-using-a-soil-warming-cable/    shows how to make one. Also there are some youtube videos.
 
They are designed to be off ground in a full size greenhouse. But I don't see why they wouldn't work in the cold frame greenhouse.  So a little closer to doable. But most of my questions still need answered .

 

[AJ Drew]

I do not know any of the answers, but wanted to jump in so this will keep in my feed.  I am very interested, will be building mine this year, and will be fun to see what we both come up with.  My plan is to build them on the south wall of a garage that has electricity.  So have been reading a bit about the electric heat strips that go under or in the soil.  Thing is, I am not really looking to build traditional cold frames where you grow in that soil.  I want to container grow.  So I might have to go with a way to heat the air.  Thinking if I have a long line of them, I can put the heater in the garage so I dont have to worry about water and electricity, then circulate air in one end and out the other end of the lined up sections.  Maybe one big long section but smaller tops so I can open areas individually.

My big thing with small plants is that I -think- it is cheaper to pay for the heat than the light.  Thinking start indoors but move them out very early.

 

[juanitos]

yeah you  don't  want to do inground cable.. on cold days your air temp will still be low, sure the inground cable will keep it a bit warmer than outside but not very effectively.. what then? you going to run separate soil and air heaters? 
Or are you only going to plant out when air temp is good? then there isn't really a need for the soil heater..
containers will stay the same as air temp. in the day they will warm up above it because they absorb heat from sun.
 
why containers:
1. ease of transplant / movement
2. separate root space for each plant to grow unhindered
3. warm up easier from air temp than in ground
 
setup:
real greenhouse plastic with good R value(insulation)
air heater (propane or electric) (optional depending when you start / climate)
black plastic floor (absorb heat from light)
black plastic pots (absorb heat from light)
 
Heated propagation tables are good for seed sprouting as you want medium to be warmer and wetter than normal. But that's just for propagation, once seeds are sprouted you put them back to normal temps, the extra medium temperature is not needed.
 
So if you have the air heater, you can plant whenever the hell you want   then it's just about how much you want to pay to run the heater.
If you don't you'll have to measure for your individual setup, will depend on volume of greenhouse, how much heat is absorbed in the day, how much is lost at night, etc.
 
So if you transplant end of may, do you really need to grow your plants longer? no not really. February to end of may is great.
 
You can start in January but probably won't see that much benefit over running cost as you will probably need heater.. 
 
if you really want heated propagation just get a heat mat from hydrofarm. that provides the heat to soil without dealing with the cable / entanglement issues. or just make a box and use a small space heater set to 80-90 it will warm all the seeds/medium you put in there.