Saturday, 2 May 2009

Sepp Holzer and micro-climate management

I've been watching films about Sepp Holzer and his amazing permaculture farm up in the Austrian mountains (see image above for taster). In particular, I've been fascinated by his micro-climate management - he's growing lemon trees on mountainsides that are 3 feet deep in snow over winter! I've been using some of his techniques to try and help my own rather sick looking lemon tree recover.

Basically, he uses three main techniques to create warm zones up in the mountains using a classic permaculture principle - catching and storing energy. Firstly, he uses large stones strewn around his cropping areas (as shown above) to absorb the heat of the sun during the day and to re-emit it at night time, taking the edge off the usual temperature drop. Another thing he's done is to build large ponds that act like the stones in absorbing and re-emitting the sun's heat, but have the added bonus of also reflecting heat and light back up towards plants growing near them.

The last technique is an adaptation of the Victorian hot bed system in which manure is buried under beds and as it rots down it heats up, creating a warmer bed for growing really early crops in the spring. Sepp Holzer's version - also known as hugelkultur - replaces manure with organic materials you'd normally stick in the composter and heavy duty bits of wood - whole branches and such like. These are buried in long ridges about 1m to 1.5m high, with steep sides, covered with cardboard or turfs and an organic mulch or soil on top. The beds get warm as they start breaking down, but the trick he uses is to arrange his rows of ridges at right angles to the prevailing wind direction so that the warmth they produce is blown back towards his fruit trees, which are grown in the ditches between the rows of warm ridges. Very clever! I might just have to try building some of these as our yard project progresses.

So back to my lemon tree - it's been looking rather ill and actually most of the leaves have dropped off. By a process of elimination, I've worked out that it's more than likely because it's been getting too cold at night time being out in the greenhouse. Hugelkultur is a little OTT for my little greenhouse and for such a little tree, so I'm trying out his other techniques - I've arranged rocks and a bowl of water around it to keep it warm and reflect more light on to it. The leaf drop seems to have stopped and it's now flowering away merrily. I'll be keeping an eye on it and will certainly try using this technique through the winter to see if I can improve on night time conditions in there for other plants too.

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