Hotbeds and Hotbins

In 1999, the year the total eclipse of the sun was visible from Cornwall, Tim and I took our then small children to see it. They were awed by the experience.

That same holiday we also visited the Lost Gardens of Heligan to see a fantastic collection of plants in 200 acres. Far from being bored, they loved it! I particularly remember their delight at the jungle walk, a riot of subtropical species.

The Victorian walled garden there helped them understand what we were modestly trying to achieve at home. We had planted 60 fruit and nut trees in what had been a very eroded arable field and were tenderly nursing them through their early years on chalk with little to no topsoil. Just about every pest turned up in that ecologically imbalanced, windy garden but we persevered and today it is our personal Eden.

Ideas for extending the growing season

I love Victorian walled gardens and the skills gardeners required to raise exotic plants as well as more common edibles in our temperate climate. I was impressed by Heligan’s coldframes where the Victorians grew pineapples in deep pits of manure. In the 19th century fresh pineapple was the ultimate in status on the master’s table.

I tucked the idea of Victorian hotbeds into a part of my mind and it wasn’t until I visited Charles Dowding, the master of No Dig market gardening, last autumn that the idea re-emerged. Like Victorian gardeners, Charles uses compost to create hotbeds. In one corner of the greenhouse he builds a square bed with board, filling it with fresh compost or manure, adding a wooden frame on the top. The heap, having adequate mass, heats up, even in winter and works as a hot bed. Charles places germinating and tender plants on top of the frame. The fresh manure radiates heat and the plants grow at a faster rate. Not a paraffin heater in sight.

In January, Charles builds an even bigger Hotbed out of six pallet sides lashed together in a rectangle outside. Into this he adds fresh manure as the engine of heat. On top he places a six-inch deep wooden frame and fills it with old manure and compost. Into this he sows carrot, spinach, lettuce, pea, spring onion and beetroot in January. After they finish he plants squash, basil, leeks, tomato… whatever he feels like. These plants grow happily until November.

Keeping the winter at bay

I came home and looked at my modest, unheated greenhouse (10 x 6 feet or 3.04 x 1.82 metres). I didn’t have the time to build a bespoke hotbed that would fit the border, so I dismantled and moved my Hotbin – a highly insulated black composter that I had been experimenting with outside – into the greenhouse. I had to refill it in layers. Woody matter at the bottom, then layers of semi-composted kitchen waste from the bin, garden trimmings and weeds of all kinds, shredded newspapers, a little horse manure, and some woody materials to keep the carbon/nitrogen balance. The idea is to get the bin composting hot so it doesn’t matter if there are pernicious weeds as any weed roots or seeds won’t survive.

The bin was filled right to the top and was then topped up every few days. So far the greenhouse has only reached – 3ºC once, despite it being cold enough outside to ice-shut its lock on some mornings. My lemon verbena plant is also holding on to its leaves.

My plan is to compost hot and after three months, add this lovely fresh organic matter to my greenhouse borders in time for the new growing season. I will also experiment with bringing on seedlings from my heated propagator on the top of it.

So if you are grower and want to start sowing seeds early you have a number of options. You can build hotbeds inside a larger greenhouse or polytunnel, or you can build the bigger six-pallet bed outside and grow from January to November. You can also add recycled window frames like author, Jack First, suggests in his book to get the bed to heat up even faster and protect tender plants from frost.

If you have limited space like me, you might try hot composting like my Hotbin. You will still get the benefit of radiating heat plus fresh, fertile compost where when you really need it, in early spring. Whatever you do, I guarantee you are going to enjoy it!

© 2013 by Maddy Harland, the co-founder and editor of internationally acclaimed Permaculture Magazinepractical solutions for self-reliance – you can find out more and download a free copy at www.permaculture.co.uk If you want to support this magazine please subscribe or give a gift subscription to a friend.

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