A hotbed how-to for propagation undercover, pros and cons

A hotbed is a rapidly created compost heap.
But how do you achieve it in the middle of winter, when there is very little green matter to provide the heat?

I show you a common material: fresh horse manure with the straw bedding. I use that because fortunately, my neighbour has a lot of it!
Horses do not digest fibres so much as cows. This makes the compost heap more aerobic and higher in nitrogen.
Nitrogen in composting terms is a green, which is necessary for heat. Plus the straw provides structure, and warmth over a longer period. Another bedding could be woodchip, but it is slower to heat.

This is a summary pf methods I have devised over 10 years of doing this in one corner of my greenhouse. The area of 1.2 m², or 4 ft.², is I reckon the minimum you need to provide a worthwhile amount of heat over a long period of propagation.
I need the heat for different seedlings, from late February until the middle of May. We top up the hotbed every three weeks or so during that period.

Filmed and edited by Edward Dowding https://edowdingfilms.onfabrik.com
At Homeacres, Somerset UK on 20th February and then on 8th March.
My helper is Adam Wood, who works permanently at Homeacres and is an expert on mycology, see his channel @myco_ad

00:00 Introduction, why I started making hotbeds under cover
01:09 Adding fresh manure with straw to the hotbed
02:12 Putting on bits of wood stage by stage, and a metal bar to keep it tight in front
03:00 Making a hotbed using different materials, and the benefits of using straw
04:13 A potential problem, ammonia within the steam
05:35 The importance of packing in as much manure as possible
06:41 Consideration of the work involved in making a hotbed like this - is it worth it?
07:22 Hotbed dimensions
09:17 My experience of making an outdoor hotbed
09:36 Concerns about pyralid in horse manure
10:18 Levelling the hotbed
11:18 Keeping the greenhouse windows open to allow gases to escape
11:49 A look at the hotbed two weeks later
12:27 Damage to seedlings from not having put the plastic back on to protect against the gases - not something to worry about too much!
13:13 A look at the temperature

See these two videos showing the outdoor hotbed I made in 2018:
https://youtu.be/ExdnLqo3rYs
https://youtu.be/tyhs7_HjAcM

More on propagation using a hotbed: https://youtu.be/nJ5csH9K3aw

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Видео A hotbed how-to for propagation undercover, pros and cons канала Charles Dowding