Thomas Crow

Add a pot of beeswax to the top of it, beeswax will hold a surprising amount of heat.

If you do stack brick around the stove, give at least a 1 inch clearance.  They're designed to radiate heat away, so holding the heat against the stove could cause some serious damage.

Also, aim a small fan towards the stove.  It will push cooler, denser air towards the stove to be warmed up which will pull air warmer away from the stove and out into the room.  We use a computer fan - it's surprising how well it works.

I live near a volcano and have good soils for this (which, seemingly, makes them bad for rammed earth).  Patent after patent suggests our allophanic clays are perfectly acceptable for geopolymers.  I just struggle to find a recipe I can understand/follow.

My goal is to have this sorted by the end of the summer.  It will change so much about our property if we could just pour stone.

Two things:

You (and all of us) have actually been manipulated to feel that guilt on a large scale.  Ultimately, big polluting mega companies figured out it was cheaper to manipulate us into feeling guilty and blaming each other than it was for said companies to clean up their act.  "The New Climate War" is worth a read/listen.  It's all about how we're actually making pretty good progress, not enough but still good, but we're being manipulated into feeling doomed.

2 -. Do your best.  When you know better, do better.

I'd focus on two things myself...

1 - I'd be looking at solar thermal solutions.  I recently picked up four solar water heaters on our local digital market for something like $150 for the lot of them.  Plumbing them in to something to warm seedling trays wouldn't be hard and doesn't have to be expensive.  builditsolar.com has some great plans and you could make some for cheap or free depending on how creative you are and how close your proximity to a town with resources.

2 - Insulation.  Doesn't have to be good.  Doesn't have to look nice.  Doesn't have to be new.  Doesn't have to be permanent.  Put things on the walls that incorporate air gaps of 1/2" at minimum and 1" at maximum.  The flimsy ass plastic window coverings you can tape to your window are actually almost as effective as a second pane of glass because the insulation value is in the air space.  Bubble wrap works well too, and you can add multiple layers of either.  

Possibly you live near enough to a town that has a junk shop at the local dump.  They will frequently have great supplies for this - possibly even cheap bags of insulation offcuts.  Used carpet from a digital marketplace could be great because often free and, thanks to the rigidity and heft, it wouldn't be too hard to develop a system to hang them from the roof to the ground and maintain an air gap between layers.

Also, I can't find it with a quick search, but not terribly long ago I watched a video on YouTube where a guy built a structure around the non-sun-facing side of his greenhouse that he filled with leaves and they just composted down over the winter and gave him some usable heat - which is just another take on what many people have already suggested.  

Oh, and what's your heat source inside your house?  Could you heat stones or bricks or water for water bottles to take to the seedlings knowing that you'll never want to do it again but if it gets you through this winter you'll have time to adapt?

We're tiny.

1.72 kW solar
440 AH, 12v AGM battery bank
Midnite Classic controller
An inverter I don't care enough about to know who manufactured it because we only use it for the fridge.
Cheap-o generator who we run pretty hard for 3 weeks to a month in the middle of the rainy season but, hopefully, after we add a wind turbine and TEG this summer, will never be run again.

We're 12v with a total usable capacity of about 240AH plus some junk batteries I picked up for scrap value that charge our computers and phones in the bedroom.  Gets us through about 3 days of no solar most of the year, will add a wind turbine and a thermoelectric generator before winter starts encroaching because there's no sense of tripling a solar array that produces near enough to 0kWh for a full month when other generation options exist and most of the year we're in excess.

That said, if my batteries shat the bed today I'd immediately get on the local digital market and buy some more used AGMs to buy me another handful of years.  

My long term goal is to be without batteries (an acceptable alternative would be only a large enough bank to get the fridge through the night -with hydro you could totally pull that off) but the combination of system stress due to dead batteries + integrating new technologies has not worked well for me in the past and invariably I'd screw up a minor detail without realising it, possibly throwing the whole of the system into danger.  

Defo the best time to integrate new tech that behaves differently is *NOT* in the hour of need.

Not that anyone asked me, mind you.

They'll definitely record it because A) good information and B) too much potential to use it as a digital product and/or part of a kickstarter bundle in future.  I would expect that those of us stuck on the outside will get free access to the recording some time in the near future.