The Garden Bonfire

         There are two kinds of garden bonfire - the stubborn voracious and the sleepy smoker .       The first takes at least one hour to get started then it will devour almost anything with a fiendish roar of flame going 20 feet into the air.     This is the fire for big hedge trimmings and heavy brashing - it needs a fair bit of wood which can be mostly green (cut within the last month).     The second starts easily and burns slowly for days or even weeks under the expert guardianship of the dedicated gardener.    It burns grassy weedy material.

         To manage your garden bonfire you really need to grasp the essentials of combustion.      Things burn when they combine with oxygen in the air to create (in the case of the garden bonfire) carbon dioxide and, in the process, give out heat.      The heat comes out as hot gases (flames) and radiation (like an electric fire).     It is the heat from one part of the fire that dries and ignites other parts of the fire.    So here are some golden rules for your bonfire:

•  First and most importantly - no bonfire will burn well unless it has a healthy "heart".      Take time and trouble over this and you are well on your way.

•  . If branches are too far apart then the heat from one will not be sufficient to ignite the other - wet wood needs to be no more than 1 inch apart.     Cut off side shoots to get your fire started.

•  If material contains too much water then it will not burn because converting water into steam takes lots of heat (called latent energy).      Let your wood sit for at least one month before attempting to burn it.

•  If there is not enough air then the combustion will be slow and cool.   A gale of wind is best for the voracious bonfire.

•  you need the following tools to work your bonfire - a sharp hand saw, a strong set of large pruners, a good hayfork, paper, matches and dry wood.

- Never use petrol or diesel to try to start your fire - it is dangerous and unnecessary.

The Stubborn Voracious

         Now lets take a closer look at the stubborn voracious and we should see the point of all this technical talk.      Here we are with a 10 foot high pile of prunings, hedge cuttings and garden rubbish.     Lesson one is "do not try to burn it when it is fresh", the sap or green wood will be very hard to burn.     Leave it at least one month and possibly more, depending how big the branches are.

         To start your stubborn voracious you will need a small sack full of dry wood from your wood shed or workshop.      Ideally this should be in the form of branches or small logs about 12 inches long and 2 or 3 inches in diameter.     This will form the heart of your bonfire.     You will also need your saw handy and possibly   heavy duty garden pruners - these are for cutting up the branches into more digestible pieces.

         On the windward side of the bonfire pile you begin by making the "heart" of the bonfire.       Lay two larger pieces of dry wood parallel to each other about 3 inches apart and with the gap aligned to the wind direction.       On top of the 2 foundation pieces lay smaller pieces at right angles to the foundation pieces so as to form a lattice work.    This second layer should be of pieces about 9 inches in length and of small diameter.     Lay a third layer on top of these and at right angles to them.     Then find some bigger dry pieces of wood and arrange them to rest over the top of your neat lattice-work.

         When your lattice-work starter fire is in place you can begin to get it going by feeding in pieces of rolled up newspaper into the tunnel you have created between the lower two foundation pieces.     Light these and keep feeding in more and more newspaper as necessary until the whole pile is burning well.      Now you have your foundation fire you must fuel it carefully with shortish pieces of timber cut from the bonfire pile.     Ideally these should be about 1 inch in diameter and about 18 inches long.     You must cut off all side shoots so that the branches can be close enough to burn well.     As the fire burns stronger you can make your pieces bigger and bigger.

         Make sure that the wind can get into the open lattice you are creating because more air means a hotter flame - a windy day is ideal.      Keep feeding your foundation fire with specially cut pieces taken from the bonfire pile.     You may have to do this for an hour or more with a big pile of hawthorn for example.     The warmth from the foundation slowly dries out the surrounding branches and suddenly a little gust of wind will start a roar of flame sending a shower of sparks to the heavens.    Now the beast that you have created is beginning to sense its power.    But your job is by no means over for now you must constantly push in material from the edge of the combustion zone into the centre where it will be quickly consumed.

         You will need a good strong hayfork to manage the fire once it gets into its voracious stage.    At this point the heat will be terrific and the fire will consume almost anything so take your chance if there is other garden refuse to be rid of.  

The Sleepy Smoker   

         And now, as they say, for something completely different: the sleepy smoker.       Some gardeners just fall in love with the sleepy smoker - I have always suspected there must be something rather addictive in the smoke.       The sleepy smoker burns grassy or leafy material that is either too much for the compost heap or just a bit too full of fibre to be of any use there.

         Once again you will almost certainly need to have a supply of good dry material to create of foundation for your bonfire.      This will roar away once you put match to it and you can now add more greener material.     But only do this at a rate the heat of the fire can sustain - and do not try to be too ambitious at this stage.    

         Once you have built up a strong "heart" in the fire then you can simply dump a great pile of green material on top of it.     This takes away the oxygen (the air) so your flames turn to smoke and the material at the base begins to carbonise rather than burn.       A smoker can simmer away like this for hours - if it looks too quiet then you must lift the centre with your hayfork.     Once more oxygen is admitted the fire should roar back into life.      The trick is to know how to manage the level of oxygen just to keep your fire ticking over.     The green material you add is slowly dried out and may suddenly burst into flame.    You can then move fairly quickly to add more green material in its turn - pulling it in with your fork from the sides.     The experts can keep their sleepy smokers going for days on end.     There's probably some kind of world record kept somewhere for how long a gardener has kept a fire going but I have no idea what it might be.

         So good luck with your bonfires!

         WS     Aug 03