I wouldn’t dare say that this is the way to make a hot bed because, like the vast majority of people, I’ve never made one before, and the only one I’ve ever actually seen was at the Lost Gardens of Heligan where they import many tons of horse manure from Newmarket for their lovely pineapple house. As I said yesterday it’s pretty hard to lay your hands on the good stuff and I know, from talking to one of the Heligan gardeners last year, that they had a similar problem with sourcing the right kind of manure to get the heat they needed. You wouldn’t go all the way to Newmarket from Cornwall if you didn’t have to. On the other hand we’re not trying to grow pineapples and I don’t have any friends in Newmarket, so hopefully Annie’s stuff (she’s no slouch as a rider) will do. I can only promise to report honestly on how this experiment turns out for good or ill.
I have to give credit to Jack First’s book –“Hot Beds: How to grow early crops using an age-old technique” 2nd Edition. I bought it last year and it’s a mine of information. There’s plenty of other information out there on the internet and after a lot of research I came to the conclusion that there’s no such thing as a perfect design but there are some good pointers. For a small bed like ours the most useful advice came on the Garden Organic website which suggested a proportion of 3:1 for manure over topping.
Just as an aside here, I’ve got a bit of a thing about perfectionism and following exact instructions. Nature doesn’t function that way at all, and so the last thing in the worldI would want to claim is any universal validity for my methods. This is just what I did – nothing more. My advice is be brave, use what you’ve got and forget experts.
Anyway – the procedure goes something like this. Build a box – mine was solid but I may yet have to drill holes in it to let air in. On the internet I’ve seen apparently successful systems with slattted bars or made from pallets. Fill it up to two thirds with fresh manure – should I have had more straw in mine? honestly I don’t know yet. Then I topped up the manure with 1/3 by approximate weight of a 50/50 mixture of topsoil and good compost with some horticultural sand added. As you see I mixed it in the wheelbarrow, raked it level and covered it with a layer of polythene held in place with a pallet.
Will it work? Well, I checked the temperature of the manure against the ambient temperature in the nearby soil. The soil temperature was at 5C and the manure (after less than 24 hours in the box), was 12.5C. You can see a soil thermometer stuck into the soil layer so I can monitor how things are going. If it fails the whole lot will be composted, and if it really flies I’ll put a couple of deckchairs on top for Madame and me to warm our bottoms.
What it offers is the potential of increasing our heated propagator space by a factor of three and increase the length of the productive season by maybe six weeks. Apart from being hard work, what is there to lose?